Docstoc

AEROMEDICAL TRAINING Review

Document Sample
AEROMEDICAL TRAINING Review Powered By Docstoc
					        TABLE OF CONTENTS
ALTITUDE PHYSIOLOGY REVIEW              PAGE 3


SPATIAL DISORIENTATION REVIEW           PAGE 17


NOISE AND VIBRATIONS IN ARMY AVIATION   PAGE 25


GRAVITATIONAL FORCES                    PAGE 40


STRESS AND FATIGUE REVIEW               PAGE 46


NIGHT VISION REVIEW                     PAGE 59
                                         Altitude Physiology Review
                                            U3005361 / Version 1
                                                01 OCT 2009
Terminal
Learning
Objective

                  Action:        Manage the physiological effects of altitude.

                  Conditions:    While serving as an aviator or an aircrew member.
                                 In accordance with AR 95-1, AR 40-8, TC 3-04.93, and
                  Standards:     Fundamentals of Aerospace Medicine.



A.      ENABLING LEARNING OBJECTIVE
                                Identify the physiological zones of the atmosphere and their
            ACTION:
                                respective altitudes.
            CONDITIONS:         While serving as an aviator or an aircrew member.
            STANDARDS:          IAW TC 3-04.93.

            a. Atmosphere.

            (1) Definition - a mixture of gases that surrounds the earth's surface. Consists of a mixture of
        water vapor and gases that extends from the surface to approximately 1,200 miles.

            (2) Held in place by gravity and it exhibits few physical characteristics that can be readily
        observed. Additionally, it shields earth's inhabitants from ultraviolet radiation.

          b. Physiological zones of the atmosphere. Man cannot physiologically adapt to all the physical
        changes of temperature and pressure, which occur within the various regions. For this reason, the
        atmosphere is further divided into three physiological divisions. The primary basis for these
        physiological zones is the pressure changes, which take place in the human body.

               (1) Efficient zone.

                  (a) Extends from sea level to 10,000 feet.

                  (b) Most individuals are physiologically adapted to this zone.

                  (c) Oxygen levels within this zone are sufficient for a normal, healthy person without the aid
                      of protective equipment.

                  (d) Barometric pressure drops from 760mm/hg to 523mm/hg in this zone.
(2) Deficient zone.

          (a) Extends from 10,000 feet to 50,000 feet.

          (b) Noticeable physiological problems, such as hypoxic hypoxia and evolved gas disorders,
              occur unless supplemental oxygen is used.

          (c) Barometric pressure drops from 523mm/hg at 10,000 feet to 87mm/hg at 50,000 feet.

       (3) Space equivalent zone.

          (a) Extends upward from 50,000 feet.

          (b) Without an artificial atmospheric environment, this zone is lethal to humans and death will
              occur rapidly.

     c. Composition of the atmosphere. The atmosphere is a mixture of several gases.

       (1) Nitrogen (N2): 78%. Most plentiful gas in the atmosphere. Essential building block of life,
           but not readily used by the body (inert gas).

       (2) Oxygen (O2). 21%.

       (3) Other gases: 1%. Carbon dioxide (CO2) - contained in the other 1% of gases and is essential
           to controlling respiration. (.03% of that 1% is CO2.)

B.          ENABLING LEARNING OBJECTIVE
             ACTION:     Identify the types of hypoxia with their respective causes.
             CONDITIONS: While serving as an aviator or an aircrew member
             STANDARDS:         IAW TC 3-04.93.

a. Hypoxia. Definition - a condition that results from an insufficient amount of oxygen (O2) in the
   body.

       CAUTION: Hypoxia can occur at any altitude and it is accumulative among the types of
       hypoxia.

     b. Types of hypoxia:

       (1) Hypemic hypoxia - caused by a reduction in the O2-carrying capacity of the blood. Anemia
       and blood loss are the most common cause of this type. Carbon monoxide from smoking and
       exhaust fumes are potentially dangerous to the aviator. Nitrates, and sulfa drugs also cause this
       type by forming compounds with hemoglobin that block its ability to attach O2 for transport.

       (2) Stagnant hypoxia - reduction in systematic blood flow or regional blood flow. Such
       conditions as heart failure, shock and the venous pooling of blood encountered during positive-G
       maneuvers predispose the individual to stagnant hypoxia. In addition, environmental extremes,
       prolonged sitting and restrictive clothing can produce local stagnant hypoxia.
  (3) Histotoxic hypoxia - results when there is interference with the use of O2 by body tissues.
  Alcohol, narcotics, carbon monoxide and certain poisons such as nicotine and cyanide interfere
  with the cells' ability to use an otherwise adequate supply of O2.

     WARNING: Carbon monoxide is a very dangerous chemical composition as it attacks the
     body’s blood and tissues simultaneously. Hemoglobin has an affinity for CO 200 times
     greater than O2.

  (4) Hypoxic hypoxia - occurs when there is insufficient O2 in the air that is breathed or when
  conditions prevent the diffusion of O2 from the lungs to the blood stream. This is the type that is
  most likely to be encountered at altitude. It is due to the reduction of the PO2 at high altitudes.
  See the chart in paragraph d under ELO #2.

c. Signs and symptoms.

  (1) Symptoms are observable by the individual air crew member in themselves. They vary from
  one person to the next, and are therefore considered subjective in nature. Examples include, but
  are not limited to the following:

     (a) Air hunger or breathlessness.

     (b) Apprehension (anxiety).

     (c) Fatigue.

     (d) Nausea.

     (e) Headache.

     (f) Dizziness.

     (g) Hot and cold flashes.

     (h) Euphoria.

     (i) Belligerence (anger).

     (j) Blurred vision.

     (k) Tunnel vision.

     (l) Numbness.

     (m) Tingling.

     (n) Denial.

     CAUTION: Each person will usually experience similar symptoms each time hypoxia
     occurs. This is why the altitude chamber is an excellent training aid.
  (2) Signs are observable by the other air crew members and therefore, are considered objective in
  nature. Examples include but are not limited to the following:

     (a) Increased rate and depth of breathing.

     (b) Cyanosis.

     (c) Mental confusion.

     (d) Poor judgment.

     (e) Loss of muscle coordination.

     (f) Unconsciousness.

     (g) Slouching.

d. Stages of hypoxia.

  (1) Indifferent stage.

     (a) Altitude - sea level to 10,000 feet (equivalent altitude with 100% O2 - 34,000 to 39,000
     feet) with ambient barometric pressure.

     (b) Symptom – the only significant effect of mild hypoxia in this stage is that night vision
    deteriorates at about 4,000 feet. The retina of the eye and the central nervous system have a
    great requirement for oxygen. To begin compensating for this your heart and breathing rate
    increase at about 4000 feet to improve circulation to brain and heart.

     (c) Decrease of visual sensitivity of up to 28% at 10,000 feet, varying among individuals.

     (d) Hemoglobin saturation - 98% at sea level decreasing to 87% at 10,000 feet.

     (e) Symptoms of hypoxia become evident at 87%
           hemoglobin saturation.

  (2) Compensatory stage. The circulatory system, and to a lesser degree, the respiratory system,
  provide some defense against hypoxia in this stage. Pulse rate, systolic blood pressure,
  circulation rate, and cardiac output increase.

     (a) Altitude--10,000 feet to 15,000 feet (equivalent altitude with 100% O2 - 39,000 feet to 42,
     000 feet) with ambient barometric pressure.
(b) Symptoms.

          CAUTION: Failure to recognize symptoms and take corrective action may result in an
          aircraft mishap.

          1. Impaired efficiency.

          2. Drowsiness.

          3. Poor judgment.

          4. Decreased coordination.

       (c) Hemoglobin saturation - 87% to 80%.

    (3) Disturbance stage. In this stage, the physiological responses can no longer compensate for
    the O2 deficiency.

       (a) Altitude - 15,000 feet to 20,000 feet (equivalent altitude with 100% O2 - 42,000 feet to
       44,800 feet) with ambient barometric pressure.

       (b) Symptoms.

          1. Sensory.

            a. Vision - peripheral and central vision are impaired and visual acuity is diminished.

            b. Touch and pain - diminished or lost.

            c. Hearing - one of the last senses to be lost.

          2. Mental - intellectual impairment is an early sign that often prevent an individual from
          recognizing disabilities.

            a. Memory.

            b. Judgment.

            c. Reliability.

            d. Understanding.

            e. Decision making/problem solving.

          3. Personality - may be a release of basic personality traits and emotions as with alcohol
         intoxication.

            a. Euphoria.

            b. Aggressiveness.
          c. Overconfidence.

          d. Depression.

        4. Performance (psychomotor functions).

          a. Coordination.

          b. Flight control.

          c. Speech.

          d. Handwriting.

        CAUTION: Failure to recognize symptoms and take corrective action may result in an
        aircraft mishap.

     (c) Signs.

        1. Hyperventilation.

        2. Cyanosis.

     (d) Hemoglobin saturation - 65-80%.

  (4) Critical stage. Within 3 to 5 minutes, judgment and coordination deteriorate.

     (a) Altitude - 20,000 feet and above (equivalent altitude with 100% O2 - 44,800 feet and
     above) with ambient barometric.

     (b) Signs.

        1. Loss of consciousness.

        2. Convulsions.

        3. Death.

     (c) Hemoglobin saturation--less than 65%.

        WARNING: When hemoglobin saturation falls below 65%, serious cellular dysfunction
        occurs; and if prolonged, can cause death.

e. Factors modifying hypoxia symptoms.

  (1) Pressure altitude - determines the PO2 in the lungs.

  (2) Rate of ascent - at rapid rates, high altitudes can be reached before serious symptoms are
  noticed.
  (3) Time at altitude (exposure duration) - usually the longer the duration of exposure, the more
  detrimental the effect of hypoxia. The higher the altitude, the shorter the exposure time required
  before hypoxia symptoms occur.

  (4) Temperature - exposure to cold weather extremes reduces the tolerance to hypoxia by virtue
  of the increase in metabolic workload. Hypoxia may develop a lower altitudes than usual.

  (5) Physical activity - when physical activity increases, the body demands a greater amount of
  O2. This increased O2 demand causes a more rapid onset of hypoxia.

  (6) Individual factors - an individual's susceptibility to hypoxia is greatly influenced by
  metabolic rate, diet, nutrition, and emotions (probably most inconsistent factor).

  (7) Physical fitness - an individual who is physically conditioned will normally have a higher
  tolerance to altitude problems than one who is not. Physical fitness raises an individual's
  tolerance ceiling.

  (8) Self-imposed stresses - smoking and alcohol increase an individual's physiological altitude
  and therefore reduces their tolerance ceiling.

f. Expected Performance Time (EPT) - The time a crewmember has from the interruption of the O2
supply to the time when the ability to take corrective action is lost.

  (1) The EPT varies with the altitude at which the individual is flying.

                ALTITUDE                                EPT__________

                FL 500 & Above                          9-12 seconds
                FL 430                                  9-12 seconds
                FL 400                                  15-20 seconds
                FL 350                                  30-60 seconds
                FL 300                                  1-2 minutes
                FL 280                                  2½-3 minutes
                FL 250                                  3-5 minutes
                FL 220                                  8-10 minutes
                FL 180                                  20-30 minutes

  (2) EPT for a crew member flying in a pressurized cabin is reduced approximately one-half fol-
  lowing loss of pressurization such as in a rapid decompression (RD).

g. Prevention of hypoxia (hypoxic).

  (1) Limit time at altitude (AR 95-1).

  (2) Use supplemental O2.

  (3) Use pressurized cabin.
     h. Treatment of hypoxia.

         (1) O2.
         (2) Descend to a safe altitude.


C.   ENABLING LEARNING OBJECTIVE
      ACTION:      Identify the signs and symptoms of hyperventilation and
                   treatment.
      CONDITIONS:          While serving as an aviator or an aircrew member.
      STANDARDS:           IAW TC 3-04.93 and Fundamentals of Aerospace Medicine.


       a. Hyperventilation - Definition - an excessive rate and depth of respiration leading to abnormal
      loss of CO2 from the blood.

       b. Causes.

         (1) Emotions.

            (a) Fear.

            (b) Apprehension.

            (c) Excitement.

         (2) Pressure breathing.

         (3) Hypoxia.

       c. Symptoms--similar to those of hypoxia.

         (1) Tingling sensations.

         (2) Muscle spasms.

         (3) Hot and cold sensations.

         (4) Visual impairment.

         (5) Dizziness.

         (6) Unconsciousness.

       d. Significance of hyperventilation.

         (1) Can incapacitate a healthy crew member.

         (2) Can be confused with hypoxia.
     e. Prevention.

       (1) Don't panic.

       (2) Control rate and depth of respiration.

     f. Distinguishing between hyperventilation and hypoxia.

       (1) Above 10,000 feet--assume hypoxia and treat accordingly.

          (a) 100% O2--if available.

          (b) Descend to a safe altitude.

       (2) Below 10,000 feet--assume hyperventilation and treat accordingly. Voluntary reduction in
       rate and depth of respiration.

D.        ENABLING LEARNING OBJECTIVE
            ACTION:      Describe the sign and symptoms of trapped gas dysbarisms and
                         their treatment.
             CONDITIONS:          While serving as an aviator or an aircrew member.
             STANDARDS:           IAW TC 3-04.93.

 a. Dysbarism - syndrome resulting from the effects, excluding hypoxia, of a pressure differential
 between ambient barometric pressure and the pressure of gases in the body. Also referred to as
 disorders.

     b. Trapped gas dysbarism.

       (1) Boyle's Law - The volume of a gas is inversely proportional to its pressure, temperature
       remaining constant.

       (2) Dry gas conditions - Under dry gas conditions, the atmosphere is not saturated with moisture.
       Basically, under conditions of constant temperature and increased altitude, the volume of a gas
       expands as pressure decreases.

       (3) Wet gas conditions - Gases within the body are saturated with water vapor. Under constant
      temperature and at the same altitude and barometric pressure, the volume of a wet gas is greater
      than the volume of a dry gas.

       (4) Types of trapped gas disorders.

          (a) Trapped gas disorders of the gastrointestinal tract.

             1. Mechanism - the stomach and intestines contains gas, which expands during ascent
             causing gas pains.

             2. Prevention.
     a. Watch your diet (if a crewmember has difficulty relieving abdominal gas pains the
     diet should be adjusted to avoid gas-producing foods).

     b. Avoid carbonated beverages and large amounts of water before going to altitude.

     c. Don't chew gum during ascent.

     d. Keep regular bowel habits.

   3. Treatments.

     a. Belching.

     b. Passing flatus.

     c. Descent to a lower altitude (if pain persists).

(b) Ear blocks.

   1. Mechanism.

     a. As the barometric pressure is reduced during ascent, the expanding air in the middle
     ear is intermittently released through the eustachian tube.

     b. As the inside pressure increases, the eardrum bulges until an excess pressure of
     approximately 12 to 15mm/Hg is reached.

      c. At this time, a small bubble of air is forced out of the middle ear and the eardrum
     resumes its normal position.

     d. During ascent, the change in pressure within the ear may not occur automatically.

     e. With the increase in barometric pressure during descent, the pressure of the external
     air is higher than the pressure in the middle ear and the eardrum is forced inward.

      f. If the pressure differential increases appreciably, it may be impossible to open the
     eustachian tube. The eardrum could rupture because the eustachian tube can’t equalize
     the pressure.

   2. Prevention.

     a. The most common complaint of crew members is the inability to ventilate the middle
     ear.

     b. This inability frequently occurs when the eustachian tube or its opening is swollen
     shut as the result of an inflammation or infection due to a head cold, sore throat, middle
     ear infection, sinusitis, or tonsillitis.

     c. Unless absolutely necessary, crew members with colds or sore throats should not fly.

   3. Treatment.
     a. Stop descent of aircraft and attempt to clear by valsalva.

     b. If the condition is not cleared, climb to altitude until cleared by pressure change or
     valsalva.

     c. Reduce rate of descent and equalize ear/sinus frequently during descent.

(c) Sinus blocks.

   1. Mechanism.

     a. Like the middle ear, sinuses can also trap gas during flight.

     b. Sinuses are air-filled, relatively rigid, bony cavities lined with mucus membranes.

     c. Sinuses are connected with the nose by means of one or more small openings.

     d. If the openings into the sinuses are normal, air passes into and out of these cavities
     without difficulty and pressure equalizes.

      e. If these openings become obstructed it may become difficult or impossible to equalize
     the pressure.

   2. Prevention.

     a. Avoid flying with a cold or congestion.

     b. Perform the valsalva maneuver more frequently.

   3. Treatment – treat a sinus block the same, as you would treat an ear block.

(d) Barodontalgia (trapped gas disorders of the teeth).

   1. Mechanism - change in barometric pressure can cause a toothache.

      EXAMPLE: Air may be trapped in the tooth by recent dental work. Air under the
     filling material will expand during ascent causing pain.

   2. Prevention--avoid flying following dental restoration or when in need of restoration.

   3. Treatment - descent usually brings relief.

   4. Referred pain.

     a. Nerve endings for sinuses and the upper teeth are in close proximity in the maxilla.

     b. On occasion, the sinuses will block putting pressure or pain on the upper teeth.

     c. Condition must be treated as a ear/sinus block.
E.           ENABLING LEARNING OBJECTIVE
             ACTION:       Describe the type of evolved gas dysbarism which occur at
                           altitude.
             CONDITIONS:           While serving as an aviator or an aircrew member.
             STANDARDS:            IAW TC 3-04.93 and Fundamentals of Aerospace Medicine.


 a. Evolved Gas Dysbarism (decompression sickness) - Occur as a direct result of a reduction in
 atmospheric pressure. As pressure decreases, gases dissolved in body fluids are released as bubbles.
 This will cause varied skin and muscle symptoms and possibly neurological symptoms.

  b. Henry's Law - The amount of gas dissolved in a solution is directly proportional to the pressure
 of the gas over the solution. This is similar to gas being held under pressure in a soda bottle. When
 the cap is removed, the liquid inside is exposed to a lower pressure; therefore, gases escape in the
 form of bubbles. Nitrogen (N2) in the blood behaves in the same manner.

     c. Mechanism.

       (1) Inert gases in body tissues (principally N2) are in pressure equilibrium with the same gases in
       the atmosphere.
       (2) When barometric pressure decreases, the partial pressures of atmospheric gases decrease
       proportionally, leaving the tissues temporarily supersaturated.

       (3) Responding to the supersaturating, the body attempts to establish a new equilibrium by
       transporting the excess gas volume in the venous blood to the lungs.

       (4) However, this is an inefficient system of removal and could lead to an evolved gas disorder.

     d. Four types of evolved gas disorders.

       WARNING: Evolved gas disorders are considered serious and medical treatment/advice must be
       sought immediately.

       (1) Bends.

          (a) Occurs when the N2 bubbles become trapped in the joints. At the onset of bends, pain
          may be mild but it can become deep, gnawing, penetrating, and eventually intolerable.

          (b) Severe pain can cause loss of muscular power of the extremity involved and, if allowed to
          continue, may result in bodily collapse.

          (c) The larger joints, such as the knee or shoulder, are most frequently affected. The hands,
          wrists, and ankles are also common sites.
     (d) It may occur in several joints simultaneously and worsen with movement.

 (2) Paresthesia (creeps/tingles).

     (a) Tingling and itching sensations on the surface of the skin are the primary symptoms of
     paresthesia. It is caused by N2 bubbles forming along the nerve tracts leading to the affected
     areas.

     (b) A mottled red rash may appear on the skin.

  (3) Chokes.

     (a) Symptoms occurring in the thorax are probably caused by innumerable small N2 bubbles
     that block the smaller pulmonary vessels.

     (b) At first, a burning sensation is noted under the sternum. As the condition progresses, the
     pain becomes stabbing with deep inhalation. The sensation in the chest is similar to what one
     experiences after completing a 100 yard dash. Short breaths are necessary to avoid distress.

     (c) There is an uncontrollable desire to cough, but the cough is ineffective and nonproductive.

     (d) Finally, there is a sensation of suffocation; breathing becomes more shallow and the skin
     has a bluish coloration.

  (4) CNS disorder.

     (a) In rare cases when aircrews are exposed to high altitude, symptoms may indicate that the
     brain or the spinal cord is affected by N2 bubble formation.

     (b) The most common symptoms are visual disturbances which vary from blind spots to the
     flashing or flickering of a steady light.

     (c) Other symptoms may be a dull-to-severe headache, partial paralysis, the inability to hear
     or speak, and the loss of orientation.

     (d) Paresthesia, or one-sided numbness and tingling, may also occur.

e. Evolved factors - evolved gas disorders do not happen to everyone who flies. Certain factors
 tend to increase the chance of evolved gas problems and reduce the altitude at which problems can
 occur.

  (1) Rate of ascent - the more rapid the rate of ascent, the greater the chance that evolved gas
  disorders will occur; the body does not have time to adapt to the pressure changes.

  (2) Altitude – there is no reliable evidence for the occurrence of DCS with altitude exposures
  below 18,000 feet, as altitudes increase so does the rate of incidence.

  (3) Age - evidence suggests that individuals in their mid-forties are more susceptible than those
  in their early twenties.

  (4) Exercise – the effect of exercise on the incidence of DCS is equivalent to increasing the
 exposure altitude 3,000-5,000 feet.
  (5) Duration of exposure - the longer the exposure, especially above 18,000 feet, the more likely
 that evolved gas disorders will occur.

  (6) Repeated exposure - the more often individuals are exposed to altitude above 18,000 feet
 (without pressurization), the more they are predisposed to evolved gas disorders.

  (7) Gender/Body build – due to emotional and political factors, studies are limited and are
  therefore inconclusive regarding gender and the incidence of DCS. There is no scientific
  validation that obesity increases the rate of incidence DCS.

f. Prevention.

  (1) Denitrogenation (prebreathing 100% O2 is required for flights exceeding 20,000 feet).

  (2) Pressurization of cabin.

  (3) Limit time at high altitude.

g. Treatment.

  (1) Descend to ground level.

  (2) 100% O2.

  (3) Seek medical advice/assistance.

  (4) Compression therapy.

h. Aircrew restrictions.

  (1) In accordance with (IAW) AR 40-8, crew members will not fly for 24 hours after SCUBA
  diving.

  (2) During SCUBA diving, excessive N2 uptake by the body occurs in using compressed air.

  (3) Flying at 8,000 feet within 24 hours after SCUBA diving at 30 feet subjects an individual to
  the same factors a non-diver faces when flying unpressurized at 40,000 feet. N2 bubbles form in
  the circulatory system.
                                       Spatial Disorientation Review
                                           U3004495 / Version 1
                                               01 OCT 2009
Terminal
Learning
Objective

                    Action:          Recognize and manage the effects of spatial disorientation.

                    Conditions:      While serving as an Army aircrew member.

                    Standards:       IAW TC 3-04.93 and The Fundamentals of Aerospace Medicine.



A.          ENABLING LEARNING OBJECTIVE

             ACTION:                Identify the mechanisms of equilibrium.
             CONDITIONS:            While serving as an aircrew member
                                    In accordance with (IAW) TC 3-04.93 and the Fundamentals of
             STANDARDS:
                                    Aerospace Medicine.


   a. Equilibrium is obtained through three systems: the visual, vestibular, and proprioceptive
systems.

     b. The three systems integrate to form a complete mental picture of orientation.

     c. The information derived from the three systems provides orientation and balance.


B.      ENABLING LEARNING OBJECTIVE

         ACTION:              Identify the role of vision in orientation.
         CONDITIONS: While serving as an aircrew member.
         STANDARDS:           IAW TC 3-04.93 and the Fundamentals of Aerospace Medicine.


     a. The role of vision:

              (1) The visual system is the most reliable system used during flight.

              (2) 80% of orientation while flying is dependent on the visual sense.

     b. The visual system:

              (1) The visual system is one of three senses that integrate to form a complete mental
              picture of orientation.
                 (2) Orientation by vision requires perception, recognition, and identification.

                 (3) The visual system has two modes of processing, focal and ambient vision.
                       (a) Focal/central vision:

                               1. Focal vision is concerned with object recognition and identification. For
                               instance, when we read a book or look at our flight instruments we are
                               utilizing our focal vision.

                               2. Focal vision cues provide the primary means by which judgments of
                               distance and depth are made. Remember your monocular cues? The images
                               we perceive throughout our lifetime are stored in memory so that we may
                               compare their size to our own position relative to them. (For example, a
                               M32A2 2 ½ ton cargo truck is of a known size, therefore, we can judge our
                               distance from it, depending on its retinal projection.)

                        (b) Ambient or peripheral vision:

       NOTE: One can fully occupy central vision with the task of reading while simultaneously obtaining
      sufficient orientation cues with peripheral vision to walk or ride a bicycle.

                               1. Responsible for orienting us within our environment.

                               2. It is the primary mode for detecting motion, although it has poor acuity
                               properties. Its function is largely independent of the function of focal
                               vision.

                               3. In the absence of the horizon, visual cues arising in the ambient visual
                               field can easily be misinterpreted and lead to disorientation.

             (4) Peripheral vision provides adequate orientation information in absence of the perception
             of information from the vestibular apparatus. An individual can still maintain balance through
             the use of the peripheral visual system of orientation.



C.   ENABLING LEARNING OBJECTIVE
      ACTION:     Identify the visual illusions.
      CONDITIONS: While serving as an aircrew member.
      STANDARDS:         IAW TC 3-04.93 and the Fundamentals of Aerospace Medicine.


     a. Visual illusions may occur when visual cues are reduced by clouds, night, and/or other obscurities
     to vision.

           (1) False horizon: The false horizon illusion occurs when the aviator confuses cloud formations
           with the horizon or the ground. This illusion occurs when an aviator subconsciously chooses the
           only reference point available for orientation.
        (a) A sloping cloud deck may be difficult to perceive as anything but horizontal if it extends
        for any great distance in the pilot’s peripheral vision. An aviator may perceive the cloudbank
        below to be horizontal although it may not be horizontal to the ground, thus flying the aircraft
        in a banked attitude.

        (b) This condition is often insidious and goes undetected until the aviator recognizes it and
         transitions to the instruments and corrects appropriately.

        (c) This illusion can also occur if an aviator looks outside after having given prolonged
        attention to a task inside the cockpit. The confusion may result in the aviator placing the
        aircraft parallel to the cloudbank.

     (2) Fascination or fixation: Occurs when aircrew members ignore orientation cues and focus
     their attention on their object or goal.

        (a) Fixation: Target fixation, commonly referred to as target hypnosis, occurs when an
        aircrew member ignores orientation cues and focuses their attention on their object or goal.
        For example, an attack pilot on a gunnery range becomes so intent on hitting the target, he
        forgets to fly the aircraft, resulting in the aircraft striking the ground, the target, or the
        shrapnel created by hitting the target.

        (b) Fascination: may occur during the accomplishment of simple tasks within the cockpit.
        Crewmembers may become so engrossed with a problem or task that they fail to properly
        scan outside the aircraft.

 NOTE: Other types of fascination are associated with wheels- up landings, rigid fixation on the lead
aircraft during formation flight, and over concentration on one instrument during instrument flight.

     (3) Flicker vertigo is technically not an illusion, however, as most people are aware from
     personal experience, viewing a flickering light can be both distracting and annoying.

        (a) Flicker vertigo may be created by helicopter rotors blades or airplane propellers
        interrupting direct sunlight at a rate of 4 to 20 cycles per second.

        (b) Other sources include such things as anti-collision strobe lights flashing, especially while
        in the clouds. One should also be aware that photic stimuli at certain frequencies can produce
        seizures in those rare individuals who are susceptible to flicker-induced epilepsy.

     (4) Confusion with ground lights: Occurs when an aviator, mistakes ground lights for stars.
     This illusion prompts the aviator to place the aircraft in an unusual attitude to keep the
     misperceived ground lights above them.

        (a) Isolated ground lights can appear as stars and this could lead to the illusion that the
        aircraft is in a nose high or one wing low attitude.

        (b) When no stars are visible due to overcast conditions, unlighted areas of terrain can blend
        with the dark overcast to create the illusion that the unlighted terrain is part of the sky. This
        illusion can be avoided by referencing the flight instruments and establishing of a true
        horizon and attitude.
    (5) Relative motion is the falsely perceived self-motion in relation to the motion of another
    object.

EXAMPLE: You are sitting in a car stopped at a stop light and unconsciously reduce your scan
outside the vehicle. Your peripheral (ambient) vision detects the motion of another car pulling up
along side your car. You perceive the forward motion of the car beside you as the rearward motion
of your own vehicle. Alarmed, you slam on the brakes.

       (b) The relative motion illusion can also occur during formation flight. The forward, aft, up,
       or down movement of a lead or trailing aircraft may be misinterpreted as movement of your
       own aircraft in the opposite direction.

       (c) The relative motion illusion can also occur to helicopter pilots hovering over water or tall
       grass. The rotor wash creates a continual waving motion, which makes it difficult to maintain
       a stationary hover point.

    (6) Altered planes of reference: Inaccurate sense of altitude, attitude, or flight path position in
    relation to an object very great in size so that the object becomes the new plane of reference
    rather than the correct plane of reference; the horizon.

       (a) A pilot approaching a line of mountains may feel the need to climb although their altitude
       is adequate. This is because the horizon, which helps the pilot maintain orientation, is
       subconsciously moved to the top of the ridgeline. Without an adequate horizon, the brain
       attempts to fix a new horizon.

       (b) Conversely, an aircraft entering a valley, which contains a slowly increasing up-slope
       condition, may become trapped because the slope may quickly increase and exceed the
       aircraft's ability to climb above the hill, causing the aircraft to crash into the surrounding
       hills.

       (c) When flying next to large cloud formations, the eyes may interpret the cloud formations
       as a horizon. The tendency would be to tilt away from the clouds.

    (7) Structural illusions: Structural illusions are caused by heat waves, rain, snow, sleet, or other
    visual obscurants.

       (a) A straight line may appear curved when viewed through heat waves.

       (b) Heavy rain against aircraft windshields may cause a pilot on half-mile final to perceive
       the runway as being 200 feet further away.

    (8) Height-depth perception illusion: Due to a lack of sufficient visual cues, the aircrew
    member will experience the illusion that they are higher above the terrain than they actually are.

       (a) Flying over an area devoid of visual references, such as desert, snow, or water will
       deprive the pilot of his perception of height.

       (b) Flight in an area where visibility is restricted by fog, smoke, or haze produces the same
       illusion.
           (9) Crater illusion: When landing at night, the position of the landing light may be too far
           under the nose of the aircraft. This will cause the illusion of landing into a hole (crater).

           (10) The size-distance illusion: A false perception of distance from an object or the ground,
           created when a pilot misinterprets an unfamiliar object's size to be the same as an object he/she
           is normally accustomed to viewing.

                             (a) An aircraft hovering close by with its dim position lights on, may appear
                             to be farther away than when viewed at the same distance with its lights on
                             bright.

                             (b) This illusion also occurs if the visual cues, such as trees, are of a different
                             size than expected. For example, the small trees of the mid-west have the
                             same shape and contrast as the tall trees of the east coast. The pilot may fly
                             his aircraft dangerously low, thinking that he is further away from the ground.

                              (c) A pilot may falsely perceive an unfamiliar LZ to be the same size as to
                              which he is used to landing. For example, a pilot who is used to landing at
                              an airfield with a large runway 200 feet wide and 5,000 feet long, may fly too
                              low if making the same approach to a small airstrip of 100 feet wide, 2,000
                              feet long.

             (11) Autokinesis: The autokinetic illusion results when a static light appears to move when it
             is stared at for several seconds. Uncontrolled eye movement may possibly cause the illusion
             of movement as the eye attempts to find some other visual reference points.

             (12) Reversible perspective: At night, an aircraft may appear to be going away when it is
             actually approaching. This illusion is often experienced when an aircrew member observes an
             aircraft flying a parallel course. To determine the direction of flight, the aircrew member
             should observe the position of the aircraft lights (red, right, return).



D.   ENABLING LEARNING OBJECTIVE
      ACTION:     Identify the function of the vestibular system.
      CONDITIONS:         While serving as an aircrew member.
      STANDARDS:          IAW TC 3-04.93 and the Fundamentals of Aerospace Medicine.


     a. Function of the vestibular system:

              (1) Visual tracking is most important function of the vestibular system. It provides input to
              the brain to trigger reflex mechanisms in the eyes so that when the head is turned, they can
              track an object accurately to prevent a blurred image on the retina.

             (2) Reflex information: The vestibular apparatus provides reflex information by providing
             the brain with information on the body’s activities. This is accomplished through what is
             called vestibulospinal reflexes. They operate to ensure stability of the body. For example, if
             one were to fall forward, the arms would come up to break the fall.
        (3) Orientation without vision: The vestibular apparatus provides the brain the necessary orientation
        information when there is an absence of vision. If we did not have the vestibular mechanism providing
        additional orientation information, we would not be able to walk in complete darkness. We would
        always lose our balance and fall.

            b. Function of the semi-circular canal:

                     (1) Right angles to each other.

                     (2) Contain endolymph fluid.

                     (3) Responsive to angular acceleration.

                     (4) Sensitive to changes in both speed and direction.

                     (5) Detects yaw, pitch, and roll.

            c. Function of the otolith organs:

                     (1) Stimulated by gravity and linear accelerations.

                     (2) Detects change in speed without a change in direction.

                     (3) Sensitive to linear acceleration and deceleration (forward, aft, up, and down).


E.      ENABLING LEARNING OBJECTIVE
         ACTION:     Identify the function of the proprioceptive system
          CONDITIONS:           While serving as an aircrew member.
          STANDARDS:            IAW TC 3-04.93 and the Fundamentals of Aerospace Medicine.

     a. Seat of the pants flying.

     b. Unreliable means of orientation.

     c. Dependent on gravity.

     d. Flying without reference to instruments.

F.      ENABLING LEARNING OBJECTIVE
         ACTION:      Identify the types of spatial disorientation.
          CONDITIONS:           While serving as an aircrew member.
          STANDARDS:            IAW TC 3-04.93 and the Fundamentals of Aerospace
                                Medicine.

          a. Type I (unrecognized): Aircrew member does not perceive disorientation of any kind.
                  (1) Depth perception, dies with a smile on his face.

                  (2) Brownout/white out.

                  (3) The leans.

         b. Type II (recognized): Aircrew member realizes a problem exists. However, does not identify it
         as spatial disorientation.

                  (1) Coriolis.

                  (2) Graveyard spiral.

         c. Type III (incapacitating): Aircrew member experiences an overwhelming physiological
         response to physical or emotional stimuli associated with spatial disorientation.

                  (1) Nystagmus (vestibuloocular interaction): Involuntary rapid oscillations of the eyes in
                   a horizontal, vertical, or rotary direction.

                   (2) Panic, freezing on the controls.

G.   ENABLING LEARNING OBJECTIVE
       ACTION:     Identify the dynamics of spatial disorientation.
       CONDITIONS:         While serving as an aircrew member.

       STANDARDS:          IAW TC 3-04.93 and the Fundamentals of Aerospace Medicine.

         a. Visual dominance.

           (1) A learned phenomena whereby one uses focal visual cues while excluding other sensory cues.
           (2) Very complex and fragile skill. Can be lost due to events that disrupt concentration on flying
           the aircraft.

           (3) Acquired through training.

         b. Vestibular suppression. Active process of visually overriding undesirable vestibular sensations.

       NOTE: An example of vestibular suppression is when a figure skater stops spinning and doesn't feel
      dizzy or overcome by nystagmus.

        c. Vestibular opportunism. The propensity of the vestibular system to fill an orientation void
        swiftly.


H.    ENABLING LEARNING OBJECTIVE
       ACTION:     Identify the measures to help prevent spatial disorientation.
       CONDITIONS: While serving as an aircrew member.
       STANDARDS:          IAW TC 3-04.93 and the Fundamentals of Aerospace Medicine.
       a. Education and training.

             (1) Simulators.

             (2) Classroom instruction.

       b. Maintain visual references.

             (1) Actual--horizon.

             (2) Artificial--attitude indicator.

             (3) Never fly VMC and IMC at the same time. Don't "feel" for the ground once visual contact is
     lost.

       c. Aircraft procedures.

             (1) Trust your instruments.

             (2) Aircrew coordination training.

       d. Avoid self-imposed stress--(DEATH).

I.   ENABLING LEARNING OBJECTIVE
      ACTION:     Identify the actions to treat spatial disorientation.
      CONDITIONS: While serving as an aircrew member.
      STANDARDS:               IAW TC 3-04.93 and the Fundamentals of Aerospace Medicine.

     a. Transfer control of the aircraft if there are two pilots (seldom will both pilots experience
     disorientation at the same time).

        b. Delay intuitive reactions.

        c. Refer to the instruments immediately upon losing the horizon as reference.

        d. Develop and maintain instrument crosschecks.

        e. Trust your instruments!
                                Noise and Vibration in Army Aviation
                                        U3004507 / Version 1
                                            1 OCT 2009
Terminal
Learning
Objective
                                  Identify the characteristics of noise and vibration in an aviation
                  Action:         environment.
                  Conditions:     Given lists of noise and vibration effects, terms, and definitions.
                                  Achieve a 70% (35 out of 50 questions answered correctly) on the
                  Standards:      comprehensive IERW exam.



A.        ENABLING LEARNING OBJECTIVE
            ACTION:            Identify the characteristics of noise in Army Aviation.
            CONDITIONS: Given lists of the effects of noise, noise related terms and
                        definitions, and noise characteristics specific to Army aviation.
            STANDARDS:         Without error identify the following:
                                a. definition of sound
                                b. definitions of the three different types of hearing loss
                                c. the decibel range of most Army aircraft
                                d. the three measurable characteristics of sound
                                e. the effects of noise


a. The nature of sound.

  (1) Sound is the mechanical radiant energy that is transmitted by longitudinal pressure waves in a
medium such as air and is the objective cause of hearing.

   (2) Sound is produced when an object or surface vibrates rapidly and generates a pressure wave or
disturbance in the surrounding air.

EXAMPLE: Air is a springy, elastic substance composed of molecules. The elasticity is due to the
tendency of these molecules to spring back to their original position of rest whenever they are
deflected or displaced by an outside disturbance or force. A sound wave is a pressure fluctuation
caused by molecules vibrating back and forth and returning to their normal position at rest.

   (3) Colliding molecules produce vibration pressure increases or a “compression;” molecules
rebounding away from each other produce a lower pressure or a “rarefaction.”

       (a) Sound can be transmitted through any elastic substance such as air, water, or bone.
               (b) The density of the substance determines the speed at which the sound and pressure waves
       will travel. The denser the substance, the faster and longer the sound will travel.

          (4) The high speed of the rotor blade compresses the air faster than the ability of the high-pressure
       disturbance to flow away.

       b. To better understand why Army aviation personnel lose their hearing, it is important to understand
       the mechanism of hearing. Hearing is the perception of sound. Sound and pressure waves must pass
       through three areas of the ear before the brain perceives them.

          (1) The external ear is the visible portion of the ear and the external auditory canal, which ends at
       the eardrum. Sound is transmitted by air in this portion of the ear.

          (2) The middle ear is the small, air-filled cavity that separates the external and inner ear. Three
       small bones or ossicles, which are the malleus, incus and stapes (hammer, anvil, and stirrup), link the
       eardrum to the inner ear and mechanically carry sound to the hearing receptors. The Eustachian tube
       connects the middle ear with the nose and permits drainage and ventilation of the middle ear. It also
       equalizes pressure between the outer ear and the middle ear.

          (3) The inner ear is the third component that lies deep within the temporal bone. It consists of two
       sections, the vestibular section and the auditory section. The vestibular section senses balance. The
       auditory section, the cochlea, is comprised of a fluid-filled chamber where the hair-like receptors for
       hearing are located. The movement of the ossicles causes hydraulic movement of the fluid. The hair
       cells detect this fluid movement and transmit electrical impulses to the brain where sound is
       interpreted.

              (a) Sound of any type generates movement of fluid that stimulates the hair cells to convert
       mechanical impulses into electrical impulses. Loud sounds may fatigue these cells to the point where
       it may take several hours of relative quiet before they can revert to their normal state.

       EXAMPLE: Hair cells can be compared to blades of grass. Walking on the grass causes it to bend,
       but then it springs back over time. However, if you walk on the grass continuously, the grass will no
       longer spring to life. Hair cells damaged from prolonged exposure to noise will not spring back.

              (b) Hair cells are grouped into bundles. Destroyed hair cells in the various bundles means loss
       of sound perception.

2.   Identify the effects of noise.

       a. Noise is defined as sound that is loud, unpleasant, or unwanted, however, the sound does not have
       to be loud to be considered a noise. It is contingent on how the listener perceives it. In aviation, noise
       could cause annoyance, speech interference, fatigue, and hearing loss.

       b. Annoying noise can affect pilots while they are performing their duties because it can interfere with
       concentration.

       c. Fatigue can be caused by a number of physiological responses that have been attributed to noise.
       Reported responses include the effects of blood flow to the skin, respiration, skeletal muscle tension,
       and constipation.
     d. Speech interference occurs when noise masks and obscures words.

     e. Hearing loss can occur due to exposure to noise that is above safe limits and damage may be either
     temporary or permanent. Overexposure to noise destroys your hearing.

3.   Identify the three measurable characteristics of noise.

     a. Noise has measurable characteristics.

        (1) Frequency is the physical characteristic that gives sound its subjective quality of pitch.
     Frequency of periodic motion is the number of times per second the air pressure oscillates. The
     number of oscillations, or cycles per second, is measured in hertz (Hz).

            (a) Human hearing range. The human ear is very sensitive and can detect frequencies from 20
     to 20,000 Hz.

            (b) Human speech range. Speech involves frequencies from 200 to 6,800 Hz. This is the range
     to which the ear is most sensitive.

           (c) Speech intelligibility. You must be able to hear in the range of 300 to 3000 Hz to
     understand speech communication.

        (2) Intensity is the physiological correlation of sound intensity or pressure to loudness. For
     auditory measurement it is convenient to convert the physical measurement of intensity to a
     logarithmic scale known as the decibel (dB) scale.


              (a) dB ranges of the human ear.

               1. 0 dB. Close to the human hearing threshold or the smallest sound heard by the average
     normal human ear. It is not the absence of sound.

                  2. 65 dB. Average level of conversational speech with moderate level of vocal effort.

                3. 85 dB. Level of steady noise that is considered hazardous regardless of the duration,
     hearing conservation measures must be taken when exposed to noise level at or above 85 dB.

                  4. 120 dB. Known as the discomfort threshold. This level of noise is uncomfortable to the
     human ear.

                5. 140 dB. Level of noise that will produce pain in the average human ear, known as the
     pain threshold

                6. 160 dB. Physical damage may result at this level of noise. The eardrum may rupture
     and the noise (pressure) may be forceful enough to disrupt the ossicles in the middle ear.

              (b) Sound pressure increases with more intense noise.

                  1. Since the decibel is a logarithmic ratio, a 20 dB increase equals a pressure increase of 10
     times.
                 2. The entire range of human hearing from 0 dB to 140 dB shows a 10 million fold
     increase in sound pressure.

        (3) Duration is characterized as how long an individual is exposed to noise.

            (a) Steady noise is sound without intermittence or significant variability in overall intensity for
     prolonged periods of time. This is the most common type of noise experienced in Army aviation and it
     originates primarily from engines, drive shafts, transmissions, rotors and propellers.

            (b) Impulse noise is a type of sound characterized by explosive noise that builds up rapidly to a
     high intensity peak and then falls off rapidly. This entire cycle is usually measured in milliseconds.
     Defined as less than one second in duration.

     b. Army noise exposure criteria. The Surgeon General has established 85 decibels as the maximum
     permissible sound level of continuous unprotected exposure to steady-state noise for eight hours.

        (1) The following table shows the recommended allowable sound intensities for the various
     duration of exposure:

                   Exposure Duration                   Maximum Exposure
                    Per Day (HRS)                          Level (dB)
                           8                                   85
                           4                                   90
                           2                                   95
                           1                                  100
                          1/2                                 105

        (2) For every five decibels noise intensity increase, the exposure time is cut in half.

     CAUTION: Unprotected exposure to noise levels in excess of 85 dB can result in temporary or
     permanent hearing loss. Aircrew members must use hearing protection to prevent hearing loss.

4.   Identify the types of hearing loss associated with prolonged exposure to noise.

     a. Hearing loss depends on several factors such as age, an individual's health, and the environment
     (lifestyle).

        (1) Conductive hearing loss occurs when there is a defect or impediment in the external or middle
     ear. This may be caused by wax, fluid, or calcification, which impedes the mechanical transmission of
     sound to the inner ear. In most cases it can be treated medically.

        (2) Sensorineural hearing loss occurs when the cochlea is damaged. It is most frequently produced
     by noise, but can also be caused by heredity, disease, and aging (Presbycusis). This hearing loss is
     permanent and usually occurs in the higher frequencies first. Substantial loss may occur before the
     speech frequencies are affected; there is no medical treatment for this type of loss; hearing aids may be
     beneficial.

           (a) Acoustic trauma. This type of damage to the ear is sudden and may cause temporary or
     permanent hearing loss.
                1. Acoustic trauma is caused by high intensity impulse noise. It can be single or repetitive
     in nature with the duration generally measured in milliseconds.

               2. Usually in excess of 140 dB.

               3. Impulse noise (blast, gunfire, etc.) is usually predictable; therefore, acoustic trauma is
     usually preventable.

        (3) Mixed hearing loss is the combination of conductive loss and sensorineural loss. An aircrew
     member with high frequency hearing loss with a middle ear infection will have conductive component
     that is treatable and sensorineural loss that is not.

     b. Noise induced hearing loss (NIHL):

        (1) Temporary Threshold Shift (TTS) results from a single exposure to a high level noise.
     Threshold shifts may last for a few minutes or for a few hours, the duration of the shift depends
     primarily upon the duration, intensity, and frequency of the noise exposure. Recovery, when noise is
     removed, is usually complete.

        (2) Permanent Threshold Shifts (PTS) is the shift that occurs when exposed to continued noise for
     15 hours. PTS could eventually result in permanent hearing loss. Recovery does not occur even
     though the noise exposure is terminated. Temporary threshold shifts eventually become permanent.
     This process cannot be predicted.

5.   Identify the characteristics of noise induced hearing loss.

     a. Noise induced hearing loss is insidious because it is usually undetectable, painless, and very
     gradual.

     b. Prolonged exposure to noise of moderate intensity may cause temporary and eventual permanent
     hearing loss.

     c. Associated with noise intensity usually below 140dB, but above 85 dB.

     d. Physical pain is usually not evident and there are often no symptoms of any hearing loss.

     e. Initially, the higher frequencies of hearing are lost. When this becomes severe enough to interfere
     with speech communications, the individual will lose the ability to understand the sounds of
     consonants in words. Consonants consist of sounds in a higher frequency range than vowels. In the
     earlier stages, communications become difficult in the presence of background noise.

     f. How can an individual tell his/her hearing has been affected? Through testing, his/her initial
     audiogram is considered a reference audiogram. All subsequent audiograms will be measured against
     the initial reading.

        (1) Audiograms are considered normal as long as hearing thresholds are 20 dB or less for all
     frequencies tested. The acoustic notch begins with a drop in hearing in the 3000-4000 Hz range, with
     recovery at 6000 Hz.
        (2) The following table shows the maximum acceptable audiometric hearing levels for Army
     aviation:

                   Frequency (Hz)          500     1000         2000   3000   4000    6000
                    Classes 1/1a            25      25           25     35     45      45
                    Classes 2/3/4           25      25           25     35     55      65


        (3) Only physicians and audiologists can diagnose noise induced hearing loss.

        (4) Audiograms can detect inaccurate readings and will re-test the subject until normal patterns of
     audiometry are achieved.

6.   Identify the noise characteristics of military aircraft.
     a. Looking at Army aircraft as both fixed and rotary wing, certain generalizations can be made.

       (1) Overall noise levels generally are equal to or exceed 100 dB. This exceeds the average 85 dB
     damage risk criteria.

        (2) The frequency that generates the most intense level is 300 Hz. Low frequency noise will
     produce a high frequency hearing loss. Providing adequate hearing protection for lower frequencies is
     very difficult due to the way lower frequencies are transmitted (vibrations).

        (3) Exposures to these levels without hearing protection will lead to definite permanent noise
     induced hearing loss.

     b. Noise in Army fixed wing aircraft originates from power plants, propellers, and transmissions.
     Their noise levels will depend on the following criteria:

        (1) Location of the engines and their proximity to the cockpit.

        (2) How much insulation they have.

      (3) The table below shows peak noise levels for Army fixed wing aircraft currently in service:

                                    Aircraft                               dB
                                  C-12 / RC-12                            * 106
                                     UC-35                                ** 96

     NOTES: *Exterior noise level, ** Cabin noise level

     c. Noise in Army rotary wing aircraft originates from power plants, rotor systems, and transmissions
     that produce significant pure tone narrow bandwidth noise.

        (1) Observation helicopters are small in size but can generate an extreme amount of noise with
     levels exceeding 100 dB.

        (2) Attack helicopters such as the AH-64 Apache is a closed cockpit helicopter, the rear seat
     occupant is exposed to engine noise at close proximity. Weapon systems can add more noise during
     mission profile.
        (3) Utility and cargo helicopters’ noise levels fluctuate with cargo doors and ramps open. Troops
     that are being airlifted should wear hearing protection. Aircrew members must ensure that passengers
     wear hearing protection while inside the troop/cargo compartment.

        (4) The table below shows Army rotary wing aircraft and their peak noise levels:

                              Aircraft                                      dB
                              UH-1H                                         102
                              AH-1S                                         105
                              OH-58C                                        103
                              OH-58D                                        100
                              CH-47D                                        112
                              UH-60A                                        108
                               AH-64                                        104
                              *TH-67                                        102

     NOTE: * Noise level for TH-67 based on noise level for a BELL 206 helicopter.

     d. Noise in Air Force cargo aircraft. Due to worldwide missions, aircrew members may have to rely
     on cargo fixed wing aircraft to transport their aircraft to distant locations around the world.

        (1) Noise levels on cargo aircraft can exceed 85 decibels during air load operations on the ground.

         (2) As passengers, aircrew members could be exposed to noise levels well above the damage risk
     criteria.

      (3) The table below shows the noise levels that aircrew members are exposed to during operations in
     or around heavy lift aircraft:

                   Aircraft                 Maximum                Pilot-Cruise
                    C-5A                     107 dB                   85 dB
                    C-141                     94 dB                   84 dB
                    C-130                     95 dB                   84 dB
                    C-17                     90.7 dB                 89.5 dB

        (4) During air load operations, aircrews must ensure the passengers and all aircrew members wear
     hearing protection to minimize the potential for hearing loss.

7.   Identify the most practical and economical method of noise reduction available to aircrew members
     a. A number of methods of protecting human hearing and/or controlling noise are available. Some
     methods are not economically feasible; others are not suitable for operational requirements. The
     following major methods of controlling noise must be considered.

        (1) Design or plan to eliminate the noise. This is the ideal way of controlling noise.

     EXAMPLE: Design a new type aircraft with decreased noise levels.

        (2) Isolate the noise source. Increasing the distance between the noise source and the exposed
     person can accomplish this.

     EXAMPLE: Move auxiliary power units away from work areas.
  (3) Enclose the noise source. This can be accomplished by using sound and energy absorbent
material (baffling).

EXAMPLE: Increase amount of insulation in the cockpit and cabin area.

   (4) Personal protective devices. These are the most practical and economical methods available for
noise protection. A number of devices are available to attenuate (reduce) the noise at an individual's
ears.

       (a) Personal protective measures have certain distinct characteristics.

          1. Attenuation is the amount of noise protection provided by a specific protective device.
The attenuation of any given noise protective device is the number of dB it reduces from the total
energy reaching the eardrum.

           2. Speech intelligibility and other acoustic signals are better understood in noisy
environments when noise protective devices are utilized. This is due to an increase in the signal to
noise ratio brought about by a reduction in the masking effect of the noise.

            3. Maximum attenuation. Maximum attenuation for any device is approximately 50 dB. At
this point sound is transmitted to the inner ear by bone conduction (vibratio
       (b) Types of personal protective measures.

           1. Ear plugs. Foam, single flange, and triple flange; these devices are inserted into the
external ear canal. They are inexpensive, easy to carry, and effective when fitted properly.

CAUTION:          Ensure that hands and earplugs are clean prior to insertion into the ear canal to
eliminate ear infection.

              a. They provide attenuation from 18-45 dB across the frequency band.

            b. They should be worn anytime an individual is exposed to noise levels in excess of 85
dB. They are very effective when worn in conjunction with the HGU-56 and IHADSS flight helmets.

           2. Ear muffs. These devices are worn covering the ear. They provide 10-41 dB protection
across the frequency band, are comfortable, and because they can be readily seen, managerial control
for wearing hearing protection is enhanced. Ground personnel and aircraft passengers must also wear
hearing protection. They are subject to hearing loss just as well as aircrew members.

          3. Headsets. These devices are worn covering the ears, but also provide radio
communication. Commonly worn in VIP type aircraft. Noise attenuation can be degraded due to
rough handling, abuse, improper fits, and deteriorated ear seals. Headsets lack the crash attenuation
provided by a helmet.

           4. Protective helmets.

             a. For aviators and aircrew members, this is the best means of personal protection. They
provide both noise and crash attenuation. The HGU-56 and IHADSS provide greater protection in the
higher frequencies. However, it is low frequency noise in the aviation environment that is the cause
for concern.
              b. The helmet is an excellent hearing protection device. It will provide optimal
protection only if certain guidelines are followed:

                 - It must fit properly.
                 - It must be worn correctly.
                 - The ear cup seals must be soft, unwrinkled, and tear free. When the seals harden,
they must be replaced.

              c. If the SPH-4B, HGU-56, and IHADSS helmets are worn properly, the noise
attenuation brings the noise exposure within the confines of the damage risk criteria for every aircraft
except the UH-60 and CH-47D.

      d. The table below shows aircraft and helmets attenuation levels without wearing earplugs:

                                                                   Effective Exposure Level
           Aircraft                   Hearing Protector
                                           HGU-56                              81.6
           OH-58D
                                           SPH-4B                              81.5
                                           HGU-56                              76.9
           OH-58C
                                           SPH-4B                              76.8
           UH-60A                          HGU-56                              90.6
                                           SPH-4B                              90.6
           CH-47D                          HGU-56                              86.8
                                           SPH-4B                              88.0
                                        IHADSS (REG)                           80.2
            AH-64
                                         IHADSS (XL)                           83.5
             C-12                       H-157 Headsets                         70.5

            e. The polymeric foam (EAR) hand formed earplug in combination with the SPH-4B,
HGU-56, and IHADSS helmets will provide additional protection from all aircraft noise in the US
Army inventory.

               f. The table below shows exposure levels when wearing both the SPH-4 helmet and
four different types of earplugs at a pilot’s station in various aircraft:

                         UH-60A           CH-47D           OH-58
     Protector
                         120 knots        100 knots       100 knots
 HGU 56/P with
Triple Flange Plug          70.6            75.5            65.7
 HGU 56/P with
Single Flange Plug          73.3            76.4            65.4
 HGU 56/P with
    Foam Plug               68.4            75.3            61.5
 HGU 56/P with
       CEPs                 73.7            75.2            66.4

               g. SPH-4B helmets attenuation levels when worn with earplugs are 1 to 2 dB lower for
each aircraft indicated above.
                    h. HGU-56 helmets attenuation levels when worn with earplugs are 2 to 3 dB lower for
     each aircraft indicated above.

     b. An aviator may find that his/her ability to hear communications in the cockpit is diminished while
     using earplugs for the first time. This is due to the fact that your subconscious is adjusting to the lower
     sound intensity. He/she may feel that he/she has to concentrate and listen more closely to the
     transmissions. Once he/she gets used to listening with the earplugs in place, he/she will find it easier
     to hear.

     c. Communications Ear Plugs (CEP) are devices used to improve hearing protection and speech
     reception communication. They include a miniature transducer that reproduces speech signals from
     the internal communication system (ICS). The foam tip acts as a hearing protector, similar to the
     yellow foam earplugs pilots wear for "double hearing protection". A miniature wire from the CEP
     connects to the communications system through the mating connector mounted on the rear of the
     helmet. CEP has recently (July 1999) been issued its airworthiness release (AWR) for all US Army
     Aircraft using the SPH-4 or HGU-56P helmets, and for the M45 Aircrew Protective Mask (ACPM) for
     all US Army Aircraft using the M24 mask. This communication device has been enthusiastically
     received within the tested pilot population. One of the advantages of the CEPs is that if there is a
     malfunction of the device, the aircraft communications can still be used.

8.   Identify the sources on non-occupational noise exposure.

     a. Noise does not end at the flight line, thus ears often never get the chance to recuperate from the
     noise exposure associated with flying. Aviators must be aware of the sources of potentially damaging
     noise exposure and take appropriate action to minimize these exposures.

     b. General aviation. Many aircrews have civilian private or commercial pilot certificates or instructor
     pilot ratings. They may fly for pleasure or additional income. This is an extremely critical source of
     exposure, since most private aircraft are flown without headsets, relying on speakers for hearing voice
     communications. Most single-engine light aircraft have noise levels in excess of 85 dB below 1000
     Hz, which require noise protection. Unprotected, aircrew members could suffer noise induced hearing
     loss.

     c. Weapons firing. This applies to several categories of weapons firing. Unprotected, these impulse
     noises can result in sustained acoustic trauma. Some high velocity small arms weapons have peak
     intensities in excess of 168 dB. All small arms in the Army produce impulse noise levels above 140
     dB. Noise protection should be used whenever aircrew members are engaged in weapons firing.
     Some sources of indirect or non-occupational exposure are hunting, skeet or target shooting.

     d. Moonlighting. A variety of off-duty jobs may expose the air or ground crew to additional
     potentially harmful noise exposures.

        (1) Bartending (95-110 dB), in a club where loud music is played.

        (2) Members of a “rock” band (110-150 dB).

     e. Contemporary music. Frequently aircrews will innocently expose themselves to extremely loud
     and sustained levels of noise via music. Surveys in Officer's and NCO clubs have revealed exposures
     and intensity levels that exceed 130 dB. This exposure has also been shown to produce permanent
     hearing loss.
        (1) Personal portable radios aim high noise levels directly into the ear canal.

        (2) Home theater systems.

     f. Hobbies and recreation. Often hobbies and recreation result in innocent and thoughtless exposure.

     g. Household chores. Even the simplest household equipment can expose an individual to
     unnecessary noise.

        (1) Lawnmowers (95-100 d
        (2) Vacuum cleaners (90-100 dB).

        (3) Blender (93 dB).

        (4) Hair dryer (80 dB)


B.   ENABLING LEARNING OBJECTIVE
      ACTION:       Identify the characteristics of vibration in Army Aviation.
      CONDITIONS:            Given lists of the effects of vibration and vibration terms and
                             definitions.

      STANDARDS:             Without error identify the short term effects of vibration and
                             define the following terms:
                              a. vibration
                              b. frequency
                              c. amplitude
                              d. duration
                              e. natural body resonance
                              f. dampening


1.   Identify vibration terminology.

     a. Vibration is the motion of an object relative to a reference position (usually the object at rest)
     involving a series of oscillations resulting in the displacement and acceleration of the object.

     b. Frequency is the number of oscillations of any object in a given time measured in cycles per
     second (cps). The international standard unit of frequency is the hertz (Hz). (1 cps equal 1 Hz).

     c. Amplitude is the maximum displacement of an object from its position at rest.

     d. Duration is the amount of time exposed to vibration.

     e. Natural body resonance is the mechanical amplification of vibration by the body occurring at
     specific frequencies.
     f. Dampening is the loss of mechanical energy in a vibrating system. This causes the vibration to
     slow down.

        (1) When the body is subjected to certain frequencies, the tissue and organs will begin to resonate
     (increase in amplitude).

        (2) The connective tissue (muscles, tendons and ligaments) that binds the major organs together
     reacts to vibrations like a shock absorber.

         (3) The reason why humans do not receive life-threatening injuries every time they go flying is due
     to the minor amplitudes of the vibration in the aircraft and the ability of the body to provide some
     dampening against those vibrations.


2.   Identify the sources of vibration

     a. Vibrations are produced within the aircraft and the environment in which the aircraft operates.

        (1) Vibrations within the aircraft originate primarily from the engines, the main rotor, and the tail
     rotor system.

        (2) Increased airspeed and internal and external loading of the aircraft can also cause vibrations.

        (3) Environmental factors such as turbulence may also intensify vibrations.

        (4) Helicopter vibrations occurs with similar intensities in all three axes of motion, (X,Y,Z).

     b. The amplitude of the vibration differs in each mode of flight. The highest level of vibration occurs
     during the transition from flight to a hover and hover to flight.

3.   Identify the effects of vibration on human performance during flight

     a. Vibration affects the aircrew member’s ability to perform simple tasks during flight.

     b. Manual coordination and control “touch” is degraded at 4-8 Hz. Pilot induced oscillations occur
     when the aircrew member over controls during turbulence and/or transition from a hover to flight.

     c. Vision could be affected due to vibration in the aircraft, visual instruments may be difficult to read.
     Helmet mount or night vision devices may vibrate at 4-12 Hz.

     d. Speech can be distorted during oscillations of 4-12 Hz. Above 12 Hz, speech becomes increasingly
     difficult to interpret.

4.   Identify the short term effects of vibration

     CAUTION: Vibration can cause short-term effects because of the body’s mechanical properties.

     a. The human body acts like a series of objects connected by springs.
   (1) The connective tissues that bind the major organs together react to vibration in the same way as
springs.

   (2) When the body is subjected to certain frequencies, the tissue and organs will begin to resonate
(increase in amplitude).

   (3) When objects reach their resonant frequencies, they create a momentum, which increases in
intensity with each oscillation.

   (4) Without shock absorption, vibration will result in damage to the mass or object.

b. Helicopters subject aircrew members to vibrations over a frequency range that coincides with the
resonant frequencies of the body. Prolonged contact with vibration causes short-term effects no the
body. The reason why humans do not receive life-threatening injuries every time they go flying is due
to the minor amplitudes of the vibration in the aircraft and the ability of the body to provide some
damping against those vibrations.


                BODY PART                   RESONANT FREQUENCY
                 Whole Body                        4-8 Hz
                Shoulder girdle                    4-8 Hz
                    Head                           25 Hz
                    Eyes                          30-90 Hz

c. Fatigue.

   (1) Vibration causes the body’s muscle groups to make reflex contractions.

   (2) When the human body is in motion, pressure receptors located in tendons and muscles
constantly measure angular position of the muscles so as to maintain posture and balance.

   (3) These receptors respond to vibration causing contraction or tightening of the muscle. For
example, vibration placed on both calves of a standing subject resulted in the subject experiencing the
sensation of leaning forward.

d. Respiratory effects.

   (1) Hyperventilation is caused when the diaphragm is vibrated at its resonant frequency of 4-8 Hz.

   (2) The result of vibrating frequencies in the diaphragm will cause “artificial respiration”.

e. Circulatory effects. Increase in pulse rate and blood pressure are other symptoms of exposure to
   vibration.

f. Motion sickness.

   (1) Vibration with a frequency of less than 1 Hz (slow rolling of a ship) can produce nausea in
susceptible people.
         (2) The Neural Mismatch Theory postulates that there is a long term memory storage of the
     “correct world,” in terms of movement as a terrestrial being, which is matched against the actual
     conditions. When these perceptions do not match, then the brain perceives an imbalance and initiates
     a reflex response in the stomach. It is a theory that motion sickness stems from the innate response
     humans have when confronted with the neural mismatch caused by the poison, the body seeks to get
     rid of the poison by vomiting.

     g. Disorientation. Vibration affects the semicircular canals and the Otolith organs, which in turn
     respond to the changes in angular and linear motions.

     h. Pain usually results from pre-existing injuries received before flying, such as stress fractures, and
     other traumas. Vibration aggravates those conditions.

5.   Identify the long term effects of vibration

     a. Raynaud’s Disease (White finger) occurs in the hands after prolonged exposure to vibration from
     power tools, jackhammers, or other such equipment that vibrates at high frequencies. Trauma occurs
     in the arterioles and nerve endings in the extremities and limits the blood flow to that portion of the
     extremity.

     b. Backache/back pain in aircrew member may result at an earlier age than normal.

        (1) The lumbar spine, in particular, is subjected to higher pressures during aircraft operations
     because the weight of the torso on that part of the spine while sitting. When the body is standing, the
     legs support most of the body's weight.

        (2) Bones, like other organs, require blood to provide nutrients for life. When the spine is
     subjected to high levels of vibration, blood flow is reduced. The reduction in blood flow results in
     premature degeneration of bone structures within the spine.

        (3) If you bend steel back and forth enough times, you can produce a weak section, which will
     eventually break. This same principle can be applied in understanding injuries to the spine.

     c. Kidney and lung damage. Currently under scientific study, the effects of vibration on the functions
     of other organs include:

        (1) Signs of overexposure to vibration may be blood in the urine (kidney).

        (2) Lung damage may result after prolonged exposure to vibration at resonant frequencies.

6.   Identify the method(s) used to reduce the vibrational threat in Army aviation.

     a. Vibration cannot be eliminated, but its effects on human performance and physiological functions
     can be lessened.

     b. Maintain good posture during flight. Sitting straight in the seat will enhance blood flow throughout
     the body.
c. Restraint systems provide protection against high magnitude vibration experienced in extreme
turbulence.

WARNING:          Body supports such as lumbar inserts and seat cushions reduce discomfort and can
dampen vibration; however, during a crash sequence they may increase the likelihood of injury due to
their compression characteristics.

d. Maintenance of equipment. Proper aircraft maintenance such as blade tracking can reduce
unnecessary vibration exposure.

e. Isolate the aircrew members or passengers. When loading patients on MEDEVAC aircraft,
remember that patients placed on the floor will experience more vibration than the one on the litter
support system.

f. Limit exposure time. Make short flights with frequent breaks, rather than one long flight, if mission
permits.

g. Let the aircraft do the work. Do not grip the controls tightly. Vibration can be transmitted through
control linkages during turbulence.

h. Maintain excellent physical condition. Fat multiplies vibration, while muscle dampens vibration.
Strong muscles act to reduce the magnitude of oscillations encountered in flight (damping). An
overweight aircrew member is more susceptible to decrements in performance and the physiological
effects to vibration.

   (1) Maintaining good physical condition lessens the effects of fatigue. Good physical condition
permits an individual to continue to function during extended combat operations with minimum rest.
Energy and alertness is what keeps an individual alive.

   (2) Maintain sufficient hydration. Drink plenty of fluids, even if he/she don’t feel thirsty, a
minimum of two quarts of water over and above fluids taken with meals. Dehydration coupled with
vibration can cause fatigue twice as fast and it will take double the time needed for recovery
                                                  Gravitational Forces
                                                  U3004504 / Version 1
                                                     01 OCT 2009
Terminal
Learning
Objective

                     Action:         Manage the effects of Graviational Forces.

                     Conditions:     In a classroom environment
                                     In accordance with (IAW) TC 3-04.93 and Fundamentals of
                     Standards:
                                     Aerospace Medicine.



A.          ENABLING LEARNING OBJECTIVE

             ACTION:               Define gravitational force terms.
             CONDITIONS:           From a List.
             STANDARDS:            IAW TC 3-04.93 and Fundamentals of Aerospace Medicine.


1.          Define Gravitational Force terminology.

a. “G” is the measure of the magnitude of an accelerative force with respect to gravity at the Earths surface.

     (1) Equal to 32.2 feet per second squared.

     (2) Acceleration continues until terminal velocity is reached.

b. Acceleration is the rate of change of velocity with respect to time.

c. Deceleration (negative acceleration) is a reduction in the velocity of a moving body with respect to time.

d. Inertia is the resistance to a change in the state of rest or motion.

     (1) A body in motion tends to stay in motion, unless acted on by an outside force.

     (2) A body at rest tends to stay at rest, unless acted on by an outside force.

e. The tri-axial reference system identifies the direction in which the body receives accelerative forces.

B.          ENABLING LEARNING OBJECTIVE
             ACTION:     Recognize the factors of acceleration with their appropriate
                         effects.
             CONDITIONS:           Given a list of terms and definitions.
             STANDARDS:            IAW TC 3-04.93and Fundamentals of Aerospace Medicine.
1.   Discuss the factors and effects of acceleration.

     Factors that determine the effects of acceleration on the human body.

     a. Intensity--the greater the intensity, the more severe the effects of accelerative forces. (Intensity,
     however, is closely related to duration)

     b. Duration--the longer the force is applied, the more severe the effects.

        (1) Ejection seat sequences expose the aviator to approximately 15g’s for about 0.1 seconds
     without difficulties. If this intensity lasted for 2 seconds, the aviator would be rendered unconscious.

        (2) There will be a 2-97 second state of unusable consciousness after normal blood pressure is
     returned. The average person has a 15 second state of unusable consciousness.

     c. Rate of onset--the faster the rate of acceleration, the more severe the effects.

     d. Body area and site--the greater the size of the body area affected, the less severe the effects.

     e. Impact direction--a force in the Gy axis will not be tolerated as well as a force applied to another
     axis because of aircraft structural and human physiological limitations.


C.   ENABLING LEARNING OBJECTIVE
      ACTION:     Identify the effects of low magnitude acceleration.
      CONDITIONS:          Given a list.
      STANDARDS:           IAW TC 3-04.93 and Fundamentals of Aerospace Medicine.


1.   Discuss the physiologic effects of low magnitude acceleration.

     REMINDER: Low magnitude accelerations are described as “G”s that range from 1 to 10 “G”s and
     lasting for several seconds.

     a. +Gz--during a +Gz maneuver, body weight increases in direct proportion to the force (200 pounds
     will weigh 600 pounds during a 3G maneuver).

        (1) Circulatory effects:

            (a) Blood pooling in the lower extremities

           (b) As the force exceeds 2G’s, blood flow to the eye decreases causing a gradual loss of
     peripheral vision (grayout)

        (2) +Gz tolerance limits:

            (a) 1.0-2.5 Gz: Blood pooling

            (b) 2.5-4.0 Gz: Grayout
       (c) 4.0-4.5 Gz: Blackout

       (d) 4.5 and above: Unconsciousness

   (3) Factors that modify +Gz tolerance:

        (a) Decremental factors are any factors that reduce the overall efficiency of the body, especially
the circulatory system

       (b) Blood volume decrease

          1. Dehydration

          2. Hemorrhage

          3. Acute alcohol abuse

          4. Varicose veins

       (c) Blood pressure decrease

          1. Due to blood loss or dehydration

           2. Illness/not physically fit

          3. Acute alcohol abuse

   (4) Incremental factors are any factors that enhance the ability of the body to withstand G-forces.

       (a) Asymptomatic Hypertension (high blood pressure without symptoms)

       (b) Fear/excitement

       (c) Tensing of muscles

       (d) Short stocky build

       (e) L-1 maneuver

       (f) Anti-G suit


b. -Gz circulatory effects:

    (1) Result in inadequate circulation to sustain consciousness. Blood pooling and stagnation occur
in the head and neck.

   (2) A rise in intracranial pressure produces head pain and visual disturbances.

c. -Gz tolerance limits:
               (1) 0.0 to -1.0 Blood pooling

               (2) -1.0 to -2.5 Vision affected

               (3) -2.5 to -3.0 Redout

               (4) Over -3.0 Incapacitation

          d. Positive and negative Gx effects:

             (1) Aircrew members experience mild transverse accelerations and decelerations when taking off
          and landing.

               (2) Individuals are more tolerant of forces on the Gx axis because transverse G’s interfere very
          little with blood flow.

               (3) Tolerance limits:

                  (a) Greater than +7 or -7 G’s breathing may become more difficult.

                 (b) Some individuals have withstood up to +20 and -20 G’s for several seconds without any
          severe effects.

          e. Gy effects:

             (1) Aircraft are structurally designed to handle aerodynamic loads which are transmitted to aircraft
          occupants primarily in the Gx or Gz axis.

              (2) This creates a structural design limitation, which makes lateral accelerations (Gy axis) the most
          lethal to aircraft and occupants.




          D.        ENABLING LEARNING OBJECTIVE
                 ACTION:               Identify the physiological effects of high magnitude
                                       acceleration/deceleration.
1.
                 CONDITIONS:           Given a list.
                 STANDARDS:            IAW TC 3-04.93 and Fundamentals of Aerospace Medicine.

                  Discuss the physiological effects of high magnitude accelerations/decelerations.

REMINDER: High magnitude accelerations/decelerations are described as G-forces exceeding 10 G’s and
lasting less than a second.

a. Physiological effects:
     (1) Minor discomfort

     (2) Minor injury

     (3) Incapacitation

     (4) Irreversible injury

     (5) Lethal injury

b. The primary source of high magnitude accelerations and decelerations are aircraft crashes. Additional
sources would be ejection seats and parachuting.


E.          ENABLING LEARNING OBJECTIVE
             ACTION:      Recognize aircrew member survivability criteria.
             CONDITIONS:           Given a list.
             STANDARDS:            IAW TC 3-04.93 and Fundamentals of Aerospace Medicine.


1.          Discuss aircrew member survivability criteria.

REMINDER: Occupant survivability during the accident sequence is contingent upon the following criteria:

a. Amount of crash forces transmitted.

NOTE: Human tolerances:

     (1) +Gx: 80

     (2) -Gx: 40

     (3) Gy axis limit is 9

     (4) +Gz: +20

     (5) -Gz: -16

b. Occupiable living space. Two objects cannot occupy the same space.

c. Aircraft design features that enhance crash survivability, (CREEP):
   (1) Container:

         (a) Acts as an effective protective shell

         (b) Crushable material to attenuate crash forces

     (2) Restraint system:
   (a) Should be comfortable and snug

   (b) Should adequately restrain major body parts

(3) Environment, make the cockpit less dangerous

(4) Energy absorption

   (a) Landing gear.

   (b) Aircraft undercarriage

   (c) Seats stroking (approximately 4g’s) in newer rotary wing aircraft

(5) Post crash factors:

   (a) Fire

   (b) Evacuation
                                              Stress and Fatigue Review
                                                U3004496 / Version 1
                                                     01 OCT 2009



Terminal
Learning
Objective
                                    Reduce the adverse effects of stress and fatigue on individual
                    Action:
                                    health, aviation safety, and mission completion.
                                    While serving as an aviator or an aircrew member.
                    Conditions:
                                    In accordance with (IAW) TC 3-04.93, FM 22-51, the Leader’s
                    Standards:
                                    Guide to Crew Endurance, Flight Stress, Health Psychology,
                                    Fundamentals of Aerospace Medicine, and DA PAM 600-24.



A.          ENABLING LEARNING OBJECTIVE

             ACTION:             Select the three definitions of stress.
             CONDITIONS: Given a list of definitions
             STANDARDS:          IAW TC 3-04.93, Flight Stress, and Health Psychology.


1.          Provide instruction on the three definitions of stress.

a. Walter Cannon (1932) researched the "fight-or-flight" response, and linked this to the arousal of the
sympathetic nervous system and endocrine system. The "rush", or "cranked-up" feeling when frightened or
surprised is a result of the rapid arousal of these systems.

b. Hans Selye (1956), considered by many to be the father of stress research, defined stress as the nonspecific
response of the body to any demand placed upon it. He called this pattern of responding the "General Adaptation
Syndrome", which consists of three stages:

     (1) Alarm Stage - the organism is mobilized to meet the threat.

     (2) Resistance Stage - the organism attempts to cope with the threat.

     (3) Exhaustion Stage - the organism fails to successfully cope with the threat.

c. Lazarus (1968) researched the "psychological appraisal process". This model suggests that when confronted
with a potential stressor, humans simultaneously evaluate the meaning of the event (positive, negative, neutral),
the degree of harmfulness associated with the event, and their available coping resources. According to this
model, stress is defined as greater perceived threat than perceived coping abilities.
B.   ENABLING LEARNING OBJECTIVE
       ACTION:     Select the signs and symptoms of stress.
       CONDITIONS: Given a list.
       STANDARDS:            IAW TC 3-04.93.


1.    Provide instruction on the signs and symptoms of stress.

      a. Physical responses to stress include both immediate symptomatology, and potentially long-term
      health consequences of unmanaged stress:

         (1) Symptomatology includes, but is not limited to:

            (a) Sweaty palms.

            (b) Increased heart rate and blood pressure.

            (c) Trembling.

            (d) Shortness of breath.

            (e) Gastrointestinal distress.

            (f) Muscle tension.

         (2) Potentially long-term health consequences:

            (a) Sleep problems (insomnia).

            (b) Backaches and other muscle pain.

            (c) High blood pressure.

            (d) Immune system suppression.

            (e) Fatigue.

            (f) Anxiety disorders.


      b. Emotional signs and symptoms can include:

         (1) Irritability.

         (2) Hostility.

         (3) Anxiety, or increased worrying.

         (4) Decreased self-esteem.
         (5) Feelings of helplessness.

         (6) Loss of interest in pleasurable activities (anhedonia).

      c. Cognitive signs and symptoms can include:

         (1) Obsessions.

         (2) Decreased attention.

         (3) Impaired memory.

         (4) Impaired judgment.

         (5) Poor psychomotor coordination (hand-eye coordination).

      d. Behavioral signs and symptoms are limitless, and can include:

         (1) Explosiveness.

         (2) Withdrawal or social isolation.

         (3) Alcohol or substance abuse.

         (4) Suicide.


C.   ENABLING LEARNING OBJECTIVE
       ACTION:      Select the correct actions to prevent suicide in a coworker who
                    hints about suicide.
       CONDITIONS:            Given a list.
       STANDARDS:             IAW DA PAM 600-24.


1.    Provide instruction on the correct actions to prevent suicide in a coworker who hints about suicide.

      a. Danger signs for suicide risk include:

         (1) Talking or hinting about suicide.

         (2) Giving away possessions or making a will.

         (3) Obsession with death.

         (4) Specific plan, with access to lethal means.

         (5) Buying a gun.
     (6) History of suicide attempts.

     (7) Alcohol or substance abuse.

b. Actions to be taken to prevent suicide:
   (1) Talk supportively, not judgmentally.

   (2) Be direct. Talking about suicide will not provoke it. If you suspect suicidal ideation, ask.
Suicidal individuals will most likely be relieved that someone is concerned about them. Admitting to
suicidal ideation is often a cry for help, and failing to address the matter directly may have disastrous
results.

   (3) Ensure the soldier receives prompt medical attention by escorting the individual to the flight
surgeon, emergency room, mental health clinic, or unit commander. Once a soldier is put in contact
with these resources, well established procedures will ensure the service member is appropriately
evaluated and treated.


D.        ENABLING LEARNING OBJECTIVE
            ACTION:      Select the impact of stress on pilot performance.
              CONDITIONS:           Given a list.
              STANDARDS:            IAW Flight Stress.


1.          Provide instruction on the impact of stress on pilot performance.

a. Pilots rely upon several cognitive abilities to successfully perform their mission. These abilities
include:

    (1) Psychomotor abilities, which include hand-eye coordination, muscular coordination, and
strength.

  (2) Attention is the cognitive ability to focus a "mental spotlight" on sensory inputs, motor control,
memories, or internal representations. It can be allocated to different activities based on perceived
importance, or salience.

   (3) Memory is the ability to recall previously learned information. Memory abilities are dependent
upon one's memory capacity, memory strategies, and rehearsal, which serve to facilitate the transfer of
information from short-term to long-term storage.

     (4) Judgment and decision making.

     (5) Prioritization of tasks.

     (6) Communication.

b. Both self-imposed stress and aviation-specific stress have the following effects on the above noted
cognitive abilities of pilots:
  (1) Psychomotor abilities decline. For example, tracking abilities decrease, with a tendency toward
more time off-target, overcorrections, and less smooth movements.

   (2) Attentional abilities may be compromised during stress in the following ways:

      (a) "Perceptual Tunneling" is the narrowing of sensory information processed by the brain (i.e.
visual field). This can result from both emotional stress and cognitive workload, and can occur in both
visual and non-visual sensory channels. For example, a pilot may attend to the most significant stimuli
(brightest light, loudest noise) at the expense of other perceptual cues.

       (b) "Cognitive Tunneling" is the narrowing of what is considered important in the attentional
field. An example would be a pilot who does not appropriately monitor his airspeed because he is
intently focusing on making the proper radio call at the proper time.

      (c) "Task Shedding" is tunneling carried to the extreme. this is when entire tasks are completely
abandoned. For example, tunneling may be missing a radio call while on approach with a caution light
illuminated, while task shedding is forgetting to do the pre-landing checks altogether.

   (3) Memory abilities decline in the following manner:

       (a) Overall memory capacity declines under stress. Whereas the average individual can hold 7
(+/- 2 digits) in memory for a short time, this declines under stress.

      (b) Memory strategies are subject to two common errors under stress:

       1. The "Simplification Heuristic" is the tendency to oversimplify information recalled from
memory during the problem-solving or decision-making process.

         2. The "Speed/Accuracy Tradeoff" is the attempt to maintain the speed of one's responses at
the expense of accuracy (most common), or the attempt to maintain the accuracy of one's responses at
the expense of speed (experienced pilots).

      (c) Stress also decreases the ability to learn new information. "Stress Related Regression" is the
tendency to forget recent learning and revert to old behaviors under stress.

      (d) Once information has been learned and is in long-term storage (like driving a car or doing
simple arithmetic), it is fairly resilient to stress.

   (4) Judgment and decision-making abilities may be compromised by stress, with inexperiences
pilots tending to make a disorganized assessment of alternatives, to rush to a decision, and to seek
premature closure.

   (5) Communication abilities may be compromised by both the speaker and listener under stress,
with changes in speech production, comprehension, and "group think". Group think is the tendency to
be more confident of our opinions when they are shared by others, and the tendency to rely on
authority figures when there is a perceived threat. This process may impede communication when
perceptions differ between group members.
E.   ENABLING LEARNING OBJECTIVE
       ACTION:      Match individual stress coping mechanisms with the four classes
                    of stress coping mechanisms.
       CONDITiONS:          Given a list

       STANDARDS:           IAW TC 3-04.93.


1.    Provide instruction on the four classes of stress coping mechanisms.

      a. Avoid stressors:

          (1) This is the most powerful technique because it involves preventing your exposure to known
      stressful events.

         (2) Examples include good time management, tough realistic training, good problem solving skills,
      and good nutrition.

         (3) Practice good cockpit and crew communication:

            (a) Talk.

            (b) Ask questions.

            (c) Utilize 3-way confirm responses.

            (d) Brief for lost communications.

      b. Change your thinking:

         (1) Avoid thoughts that reinforce a sense of invulnerability, impulsivity, and machismo.

         (2) Avoid absolutes and perfectionism.

         (3) Avoid a "pessimistic explanatory style", which is the tendency for one to attribute the negative
      events of their lives to an internal cause that is both global and stable (i.e. "I am inadequate at
      everything and I always will be.").

         (4) Focus on the here and now.

         (5) Recognize the choices you make, and increase your sense of personal control.

         (6) Utilize positive and empowering self-statements.

      c. Learn to relax:

         (1) The opposite of stress is relaxation. You cannot be stressed and relaxed at the same time, so
      learn to relax to combat your stress.
        (2) Utilize deep breathing, in particular diaphragmatic breathing, progressive muscle relaxation, or
     guided imagery to induce a relaxation response.

        (3) Don't let a busy schedule crowd out the activities that you normally do to relieve stress (i.e.
     hobbies).

     d. Ventilate stress:

        (1) A regular exercise routine of 30 minutes of aerobic activity three to four times a week has been
     shown to help prevent stress and combat its effects.

        (2) Talk it out to gain support and understanding. Talk to professionals to gain insight about
     problem-solving methods when support from others doesn't ameliorate the stressor. Resources
     include:

           (a) Friends and family members.

           (b) Flight surgeon and aeromedical physical assistant.

           (c) Psychiatrist, psychologist, and social worker.

           (d) Chaplain.

           (e) ADAPCP (Army Drug and Alcohol Prevention and Treatment Program).


F.   ENABLING LEARNING OBJECTIVE
      ACTION:     Select the factors that will decrease one's vulnerability to combat
                  stress.
      CONDITIONS:           Given a list.
      STANDARDS:            IAW Flight Stress and FM 22-51.


1.   . Provide instruction on the factors that will decrease one's vulnerability to combat stress.

     a. Combat stress is a range of signs and symptoms that may be experienced by soldiers in combat.
     Examples of signs and symptoms, in increasing severity, include:

        (1) Hyperalertness.

        (2) Fear and anxiety.

        (3) Physical stress complaints.

        (4) Loss of confidence.

        (5) Impaired duty performance.

        (6) Erratic actions or outbursts.
         (7) Freezing or immobility.

         (8) Impaired speech or muteness.

         (9) Impaired vision, touch, or hearing.

         (10) Weakness or paralysis.

         (11) Hallucinations or delusions.

      b. If less severe warning signs respond quickly to helping action, continue to monitor the soldier until
      all signs resolve; the soldier will likely not need to be evacuated or relieved of his duties. If warning
      signs persist or worsen, and interfere with the soldier's duty performance, medical treatment facilities
      can provide brief restorative treatment with a timely return to duty.

      c. Factors that may decrease one's vulnerability to combat stress include:

         (1) Competence in your work.

         (2) Confidence in your abilities.

         (3) High morale, group cohesion, and esprit de corps.

         (4) Control, or even perceived control.


G.   ENABLING LEARNING OBJECTIVE
       ACTION:      Select the signs and symptoms of fatigue.
       CONDITIONS:          Given a list.
       STANDARDS:           IAW TC 3-04.93 and Leader's Guide to Crew Endurance.


1.    Provide instruction on the signs and symptoms of fatigue.

      a. Fatigue is the state of feeling tired, weary, or sleepy that results from periods of anxiety, exposure to
      harsh environments, or loss of sleep.

      b. Sleep deprivation, disrupted diurnal cycles, and stressful life events all play a role in producing
      fatigue and impairing performance.

      c. Signs and symptoms of fatigue include:

         (1) Attention and concentration are difficult.

         (2) Feel or appear dull and sluggish.

         (3) General attempt to conserve energy.
         (4) Feel or appear careless, uncoordinated, confused, and irritable.

        (5) The cognitive deficits are often seen before the physical effects are felt. Therefore, fellow crew
      members may notice an aviator's decreased attention and concentration abilities before the aviator is
      aware of it.


H.   ENABLING LEARNING OBJECTIVE
       ACTION:      Select the effects of fatigue on performance.
       CONDITIONS:          Given a list.
       STANDARDS:           IAWTC 3-04.93, Flight Stress, and Leader's Guide to Crew
                            Endurance.


1.    Provide instruction on the effects of fatigue on performance.

      a. Reaction times increase, and the quality of motor movements decrease through:

         (1) Errors in timing and accuracy of responses.

         (2) Not as smooth on the controls.

         (3) Slow and irregular motor inputs.

      b. Attention is reduced:

         (1) A "Lapse" of attention is a transient episode of a complete loss of awareness and failure to
      respond to external stimuli. This is also referred to as "microsleeps". These usually last from 1 to 10
      seconds, and increase in number and duration as sleep deprivation increases.

         (2) Cognitive and Perceptual Tunneling under stress.

         (3) Need enhanced stimuli to maintain attention.

         (4) Overall reduced audio-visual scan.

      c. Memory is diminished:

         (1) Inaccurate recall of operational events.

         (2) Ability to learn new information is compromised.

      d. Overall poor and careless performance.

      e. Greater tolerance for error.

      f. Impairments in communication, cooperation, and crew coordination:

         (1) Conversations become more fragmented and repetitive.
         (2) Misinterpretations occur more easily.

         (3) Increased potential for error in communicating critical mission, flight, or safety information.


I.   ENABLING LEARNING OBJECTIVE
       ACTION:     Select the characteristics of the body's diurnal rhythms.
       CONDITIONS: Given a list.
       STANDARDS:          IAW Leader's Guide to Crew Endurance.


1.    Provide instruction on the characteristics of the body's diurnal rhythms.

      a. We have an intrinsic biological clock with a cycle of roughly 24-25 hours.

      b. The diurnal rhythms control:

         (1) Alertness.

         (2) Core body temperature.

         (3) Heart rate.

         (4) Hormonal secretions.

      c. Performance varies with these cycles. In the typical circadian cycle, performance peaks between
      0800 and 1200 hours, and falls to a minimum circadian trough between 0300 and 0600.

      d. While the body clock is inherently capable of monitoring the passage of time, it differs from most
      clocks in that it is flexible and must be set, or synchronized, before it can accurately predict the timing
      of events. External synchronizers, or Zeitgeber (German for "time givers") are:

         (1) Sunrise or sunset.

         (2) Ambient temperature.

         (3) Social cues and meals.


J.   ENABLING LEARNING OBJECTIVE
       ACTION:       Select the definition of circadian desynchronization.
       CONDITIONS:           Given a list.
       STANDARDS:            IAW Leader's Guide to Crew Endurance.
1.    Provide instruction on the definition of circadian desynchronization.

      a. Circadian Desynchronization, or "jet lag", is due to rapid travel from one time zone to another,
      which causes the body to resynchronize its diurnal rhythms to the local geophysical and social cues.
      Until intrinsic rhythms are reset, sleep disorders and fatigue will prevail.

         (1) Eastward travel shortens the day.

         (2) Westward travel lengthens the day.

         (3) Resynchronization occurs much more rapidly when traveling west.

      b. Shift work can have effects similar to crossing time zones due to the changes in light exposure and
      activity times.


K.   ENABLING LEARNING OBJECTIVE
       ACTION:       Select the characteristics of the sleep cycle.
       CONDITIONS:            Given a list.
       STANDARDS:             IAW Leader’s Guide to Crew Endurance.


1.     Provide instruction on the characteristics of the sleep cycle.

      a. Sleep is not simply being unconscious. It is a life-essential, active, recuperative process.

      b. The sleeping brain cycles through rapid eye movement (REM) and Non-REM sleep stages. It takes
      about 90 minutes to cycle once through all these stages of sleep, and the brain normally cycles through
      this 5 to 6 times a night. As a result, the average person sleeps 7 to 9 hours per night.

      c. The duration and quality of sleep are dependent upon body temperature. People sleep longer and
      report a better night's sleep when they retire near the temperature trough.

      d. It is the timing of sleep, not necessarily the amount of sleep that is most significant.

      e. Sleep efficiency deteriorates with age. Older individuals spend less time in deep Non-REM sleep,
      and nighttime awakenings are more common.


L.    ENABLING LEARNING OBJECTIVE
       ACTION:     Identify the factors that determine the sleep required by the
                   average aircrew member.
       CONDITIONS:          Give
       STANDARDS:           IAW Leader’s Guide to Crew Endurance.
1.   Provide instruction on the factors that determine the sleep required by the average aircrew member.

     a. Individuals cannot accurately determine their own impairment from sleep loss.

     b. Sleep can be reduced 1 to 2 hours without performance decrement over an extended period,
     although the individual must return to a normal sleep length once the period ends.

     c. Five hours a night is the absolute minimum for CONOPS (i.e. 14 days).

     d. Some individuals may tolerate as little as 4 hours per night for short periods (up to a week), but
     there is no easy way to determine who will function best with the least sleep.

     e. Sleep restriction decisions and crew endurance planning should consider:

        (1) The complexity of the job.

        (2) The potential for loss from errors.

        (3) Individual tolerance to sleep loss.


M.   ENABLING LEARNING OBJECTIVE
      ACTION:       Select strategies for preventing fatigue.
      CONDITIONS:              Given a list.
      STANDARDS:               IAW TC 3-04.93, FM 26-2, Fundamentals of Aerospace
                               Medicine, and Leader’s Guide to Crew Endurance.


1.   Provide instruction on the strategies for preventing fatigue.
     a. Schedule appropriate sleep periods.

     b. Prevent and/or control circadian desynchronosis by maintaining a consistent sleep schedule. If
     circadian desynchronosis is unavoidable (shift work or time zone change), then implement
     countermeasures to ensure adequate sleep quality such as:

        (1) Minimizing daylight exposure during sleep periods.

        (2) Controlling the sleep environment (dark, cool, noise).

        (3) Utilize napping.

     c. Build endurance through physical conditioning and good stress management skills.

     d. Practice good nutrition habits.

     e. Practice good "Sleep Hygiene":

        (1) Use bed for sleep and sex only.
     (2) Establish a bedtime routine.

     (3) Avoid looking at clocks. Instead, set backup alarms.

f. Napping:

    (1) When sleep is not available, or shortened by operational constraints, naps are a viable
alternative.

     (2) Naps as short as 10-minutes are restorative.

   (3) Longer naps (greater than 45-minutes to 1 hour) may result in a period of sluggishness called
"Sleep Inertia", which can last for 5- to 20- minutes after awakening.

     (4) Best to nap during circadian troughs (0300 to 0600, and about 1300 to 1500).


N.          ENABLING LEARNING OBJECTIVE
             ACTION:     Select the appropriate treatments for sleep deprivation and
                         fatigue.
              CONDITIONS: Given a list.
              STANDARDS:         IAW TC 3-04.93 and Leader’s Guide to Crew Endurance.


1.          Provide instruction on the appropriate treatments for sleep deprivation and fatigue.

a. Get adequate rest and natural sleep (not drug-induced). Alcohol is the most common sleep aid in the
United States, but it suppresses REM sleep and will leave you feeling unrefreshed upon awakening.

b. Control the sleep environment.

c. Rotate duties to avoid boredom.

d. Avoid complex tasks that require intense mental activity.

e. Limit work periods and delegate responsibility. If possible, suspend activity during periods when
fatigue is higher and efficiency is lower.

f. Remove yourself from flying duties when fatigue affects the safety of flight.

g. Use brief periods of exercise to increase your level of alterness.

i. Practice good nutrition habits by limiting caffeine and eating in moderation.
                                        Night Vision Orientation
                                         U3004500 / Version 1
                                             01 OCT 2009

Terminal
Learning
Objective
                                   Identify the effects of visual limitations during night flight.
                   Action:
                                   While performing as an aircrew member.
                   Conditions:
                                   In accordance with (IAW) TC 3-04.93, FM 3-04.203, FM 8-50, AR
                   Standards:
                                   40-501, and AR 40-8.

A.        ENABLING LEARNING OBJECTIVE
            ACTION:              Identify the components of the human eye and their functions.
            CONDITIONS:          Given a list of components of the human eye and their functions.
            STANDARDS:           IAW TC 3-04.93 and FM 3-04-203


1.        Discuss the components of the human eye and their functions.

a. The cornea is the transparent protective tissue located over the front of the eye. It is almost circular
in shape and projects forward. The degree of curvature varies with each individual.

b. The iris is the round pigmented (colored) membrane surrounding the pupil, having ciliary muscles
that adjust the size of the pupil to regulate the amount of light entering the eye.

c. The pupil is the opening in the center of the iris (black center portion). It allows light to enter the
eye. During daylight conditions, the pupil constricts, during dark conditions the pupil dilates.

NOTE: Pupil size is inversely related to the amount of light present. Increases in pupil diameter
decreases image sharpness in a less than perfect lens system (i.e., most eyes). Aviators who have mild
refractive errors may not need to wear their glasses during daylight viewing conditions when pupil size
is small. However, at dusk or night, the pupil becomes larger causing vision to blur unless corrective
glasses are worn. Aviators who have mild refractive errors in their lens system must wear properly
fitted glasses for night operations.

d. The lens is a transparent, biconvex membrane located behind the pupil. The lens directs light rays
entering the pupil upon the retina.

e. The retina is a thin multi-layered membrane which covers most of the posterior compartment of the
eye. The retina contains the rod and cone cells of the eye. These cells allow us to see. The retina also
contains a coloring tint called rhodopsin or visual purple, which aids in the effectiveness of the rods
during low light conditions. When exposed to sunlight, the retina cells become bleached resulting in a
temporary decrease in night vision.
      NOTE: The retina is a complex structure consisting of ten layers. One such layer, the Jacob’s
      membrane, contains the photoreceptor cells, rods, and cones, so named because of their shape. These
      photoreceptor cells translate light images into electrical pulses for transmission via neurons to the
      brain. Cones operate most efficiently at ordinary illumination levels, which prevail throughout the day
      and in normally lighted rooms at night. When the illumination decreases to about the level of full
      moonlight, rods are most effective.

          (1) Cone cells allow an individual to identify colors. They are utilized primarily during daylight
      hours or in other time periods when a bright light source is present.

              (a) Seven million contained in the fovea and parafoveal regions of the retina.

              (b) Sharp visual acuity and color sense due to 1:1 ratio of cone cells to neuron cells.

           (2) Retinal blind spot.

              (a) The day blind spot results from the existence and location of the optic disk within the
      retina. The optic disk is formed where the optic nerve enters the retina. The optic disk contains no
      photoreceptor cells (cones and rods). The day blind spot covers an area of 5.5 to 7.5 degrees within an
      individual's visual field and is located about 15 degrees from the fovea.

             (b) Viewing with binocular vision compensates for the day blind spot. Each eye overlaps the
      other when viewing. The day blind spot is not normally noticed unless one eye is not being used for
      viewing.


B.   ENABLING LEARNING OBJECTIVE
       ACTION:      Identify the functions of the rod cells during night flight.
        CONDITIONS:         Given a list of functions.
        STANDARDS:          IAW TC 3-04.93 and FM3-04.203


1.    Discuss the functions of the rod cells during night flight.

      a. Rod cells allow us to identify the outlines of shapes and the silhouettes of objects. Rod cells are
      utilized mostly during time periods or conditions of low ambient lighting and darkness.

         (1) The peripheral area of the retina is much more sensitive to light than the fovea (cone cells only)
      and parafovea regions (cone and rod cells). There are one hundred and twenty million rod cells
      located within the peripheral regions of the retina.

         (2) Decreased visual acuity, color sense, and increased light sensitivity of the peripheral regions of
      the retina are directly related to the ratio of rod cells to neuron cells (10:1 up to 10,000:1).

         (3) Use of peripheral vision while scanning during unaided night flying will greatly assist an
      individual in maintaining a positive visual identification and location of flight hazards.

      b. Retinal night blind spot.
        (1) The night blind spot occurs due to the total absence of rod cells in the fovea and the lack of rod
     cell stimulation within the parafoveal regions.

        (2) These regions are filled almost exclusively with cone cells, which are inactive due to the loss of
     ambient light. The non-effectiveness or inactivity of the cone cells causes or creates the night blind
     spot located within the center of the visual field encompassing an area of 5 to 10 degrees in width.

     Example: To correct for this limitation, use of proper scanning techniques with ten degree circular
     overlap or off center viewing will assist the crew member in identifying and maintaining visual
     reference of objects, possible hazards, and position of aircraft.


C.   ENABLING LEARNING OBJECTIVE
      ACTION:     Identify the different types of vision when viewing during
                  decreased ambient light conditions.
      CONDITIONS: Given a list of the different types of vision.
      STANDARDS:           IAW TC 3-04.93 and FM 3-04.203.


1.   Discuss the different types of vision when viewing during decreased ambient light conditions.

     a. Mesopic vision.

        (1) During dawn and dusk lighting conditions and full moonlight time periods.

        (2) Parafoveal region, a mixture of cones and rods, becomes the primary source of vision.

        (3) Visual acuity and color perception is limited due to the decrease of cones, and limited quantity
     of rods. Mesopic viewing period is considered the most dangerous period for viewing and depth
     perception.

     b. Scotopic vision.

        (1) Night vision (partial moon and starlight lighting conditions).

        (2) Use of peripheral vision (mostly rods).

        (3) Acuity degraded to 20/200. Silhouette recognition degraded and loss of color perception. An
     individual can identify shades of black, gray, and white.

        (4) Performance of off-center viewing and ten-degree circular overlap scanning techniques are
     necessary to compensate for the night blind spot.


D.   ENABLING LEARNING OBJECTIVE
      ACTION:     Identify the factors that affect dark adaptation.
      CONDITIONS:          Given a list of dark adaptation factors.
      STANDARDS:           IAW TC 3-04.93 and FM 3-04.203.
1.   Discuss the factors that affect dark adaptation.

     a. Photosensitivity of the eye is one contributing factor that affects dark adaptation.

        (1) Cones contain a chemical called iodopsin. Cone cells pick up certain colors depending on their
     pigmentation sensitivity. These colors are red, blue, yellow, or green.

         (2) Rod cells are activated by a chemical known as rhodopsin (visual purple). Rhodopsin increases
     the rods effectiveness during dark viewing periods. On average, it takes 30 to 45 minutes to achieve
     full effectiveness for rods to be dark adapted for night vision.

     b. The bleaching effect of the photoreceptor cells is another factor that affects dark adaptation.

        (1) Bleaching of the cones and rods occurs when eyes are unprotected and exposed to direct bright
     light or solar glare.

        (2) Cumulative unprotected exposure to bright light or solar glare may increase dark adaptation
     time up to 2 to 5 hours, causing negative effects upon night vision acuity.

        (3) The duration of exposure of strobe light versus flare may have adverse effects to night vision
     acuity and dark adaptation.

     c. Poor nutrition and dietary habits are other contributing factors affecting dark adaptation.

         (1) Vitamin A deficiency hinders production of rhodopsin, which is required for the effectiveness
     of the rods during dark viewing periods or conditions.

        (2) Consuming a well balanced diet that includes such foods as milk, cheese, carrots, green leafy
     vegetables, and organ meats (liver, heart etc.), will provide sufficient amounts of Vitamin A required
     for the production of rhodopsin.

     WARNING: Do not supplement Vitamin A in its pure form; it may have a toxic physiological
     effect. If supplementing for Vitamin A is necessary, a One a Day multivitamin is sufficient for the
     production of rhodopsin. Consult a Flight Surgeon before taking Vitamin A supplements.

E.   ENABLING LEARNING OBJECTIVE
      ACTION:        Identify limitations of night vision.
      CONDITIONS:             From a list of night vision limitations.
      STANDARDS:              IAW TC 3-04.93 AND FM 3-04.203.


1.   Discuss limitations of night vision.

     a. Depth perception.

        (1) Perception may be that an individual believes or assumes that he/she is higher in altitude than
     he/she actually is (false interpretation or judgment of actual altitude related to poor depth perception).
   (2) Use proper crew coordination to assist in determining actual altitude.

   (3) If mission permits use a search light or landing light. Utilizing these methods will greatly assist
an individual in obtaining clarity in relation to his/her aircraft’s position and altitude in regard to the
ground or objects below it.

b. Visual acuity.

   (1) Visual acuity during the photopic period is at best (20/20). While viewing during scotopic
periods, visual acuity degrades to 20/200 or greater.

   (2) Loss or degraded image sharpness and clarity.

Note: Performing preflight mission planning with a complete crew is essential when performing night
flight operations. Identifying published hazards on the map in relation to a flight route, noting their
location and altitudes will greatly assist in the safe completion of such flights.

When possible, perform day reconnaissance flights to prepare for night flight operations. Identify and
note all unpublished obstacles and hazards in regards to their locations and altitudes. Disseminate this
information to all crew members and flight operations for updating of unit maps.

c. Night blind spot.

   (1) The night blind spot increases in size with distance.

   (2) Proper scanning techniques must be employed to avoid hazards.

d. Dark adaptation period.

   (1) The use of red lens goggles while remaining in an artificially lighted area, will assist in
decreasing the average amount of time necessary to properly dark adapt.

   (2) Unprotected exposure to bright light or solar glare during day flights, night flights, and crew
resting time periods adversely affects night vision acuity and dark adaptation sensitivity of the rod
cells. Normally it takes 3 to 5 minutes to regain full dark adaptation from an unprotected exposure to
bright light. The time it takes to readapt may be increased due to poor night vision preparation,
decreased levels of rhodopsin, and multiple exposures during flight.

    (3) Blue wavelength light can have adverse effects upon night vision acuity, dark adaptation, and it
creates the onset of night myopia (near sightedness) during flight. This may occur by having the
console lighting intensity set too high. Operating console lighting and if applicable rear cargo area
overhead light (blue or white) at high levels of intensity during extended flight time will bleach out the
rhodopsin. Set console lighting intensity high enough where the pilot can read the information
provided by the instruments without having to stare in order to gain the information (maintain safety of
flight). Crew members in the back of the aircraft will inform pilots up front prior to operating rear
compartment lights. Crew members will use the lowest possible intensity level to perform tasks and
not allow the light to bleach out the other crew member's rhodopsin.

e. Loss of or degraded color vision.
  (1) Due to the lack of cone cell stimulation, color perception will be degraded or lost. Obstacles
may not be seen or identified as rapidly as they would be during the day.

   (2) Color perception will be limited to shades of gray, black, and white. This can only intensify
your visual limitations during night unaided flying.

  (3) Rod cells are used primarily at night to identify the outline of obstacles (silhouette recognition)
which will assist an individual in determining their shapes and sizes.

f. Night myopia occurs due to blue wavelengths of light prevailing in the visible spectrum. Because
of this, slightly nearsighted (myopic) individuals will experience visual difficulty at night when using
blue-green lighting.

   (1) Aircrew members with perfect vision will find that image sharpness will decrease as pupil
diameter increases. For individuals with mild refractive errors, these factors combine to make vision
unacceptably blurred.

   (2) These factors become important when aircrew members are relying on terrain features during
night unaided flights. Special corrective lenses can be prescribed to correct for night myopia.

Note: The visual system is the most reliable of the senses, however, some illusions can result from a
misinterpretation of what is seen. As visual information decreases, the probability of spatial
disorientation increases. Reduced visual references may cause several visual illusions.

g. Visual Cues (binocular and monocular) are harder to distinguish when viewing under decreased
ambient light conditions. This viewing condition causes aircrew members to stare at objects or terrain
features for longer durations. Misinterpretation of what is viewed is often due to the decreased
ambient light conditions.

Note: Proper crew coordination and communication combined with a detailed day reconnaissance
flight and map reconnaissance prior to actual night unaided flight will greatly reduce the negativity
when viewing under darkened conditions.

    (1) Binocular cues depend on the slightly different view each eye has of an object. Binocular
perception is of value only when the object is close enough to make a perceptible difference in the
viewing angle of both eyes. Distances are usually so great in the flight environment that these cues are
of little value especially viewing under dark conditions. These cues operate on more of a subconscious
level than monocular cues do. Study and training will not greatly improve them.

    (2) Monocular cues are derived from experience and are subject to interpretation. Monocular cues
can assist an individual in identifying possible hazards to include man-made structures, associated
terrain, and actual position of the ground in reference to present altitude and position.

       (a) Geometric perspective can be remembered by using the acronym LAV.

          1. Linear perspective.

          2. Apparent foreshortening appears elliptical (narrow).

          3. Vertical position in the field.
            (b) Retinal image size can be remembered by using the acronym KITO.

                1. Known size of objects.

                2. Increasing or decreasing size of objects.

                3. Terrestrial association.

                4. Overlapping contours or interposition of objects.

            (c) Aerial perspective is when distant information can be gained by the clarity of an object or
     by the shadow that is cast by an object.

                 1. Fading colors or shades occurs when objects viewed through haze, smoke, or fog are
     seen less distinctly and appear to be at greater distance than they actually are. If atmospheric
     transmission of light is unrestricted, an object is seen more distinctly and appears to be closer than it
     actually is.

                2. Sharpness and clarity of details or texture is lost or is less apparent with distance.

            (d) Motion parallax (one of the most important cues to depth perception) is the apparent,
     relative motion of stationary objects as viewed by a moving observer. Near objects appear to move
     past or opposite the landscape. Far objects seem to move in the direction of motion or remain fixed.
     The rate of apparent movement depends on the distance the observer is from the object. Rapidly
     moving objects are judged to be near while slow moving objects are judged to be distant.


F.   ENABLING LEARNING OBJECTIVE
      ACTION:     Identify the methods to protect visual acuity from night flight
                  hazards and limitations.
      CONDITIONS:           Given a list of night flight hazards.
      STANDARDS:            IAW TC 3-04.93, FM 3-04.203, and AR 40-8.


1.   Discuss the methods to protect visual acuity from night flight hazards and limitations.

     a. Lasers are utilized throughout the United States armed services and foreign militaries. The use of
     lasers as a weapon system has and will continue to occur by our opposing forces. Most lasers that
     generate enough power (intensity) will not be seen by the naked eye. Even when flying under aided
     conditions laser exposure is a possibility.

        (1) Lasers injuries are primarily associated with the eyes, and can occur from a considerable
     distance. Distance is the best protection, but if that is not possible the use of laser specific protective
     goggles and visors B-LPS (Ballistic Laser Protective Spectacles) will provide protection.

        (2) During pre-mission planning, an individual should attempt to identify what types of lasers
     he/she may be exposed to, and where and when these exposures are most likely to occur. Identifying
     the specific type of laser will assist an individual in obtaining the correct laser protective goggle or
     visors that are required prior to flight.
   (3) Unprotected laser exposure impairs night vision acuity.

b. Nerve agent hazards are always a possibility and can be present during night operations.

   (1) The timely manner in which an individual identifies the physiological effects of nerve agents
during night operations may determine the success and survivability of the crew.

        (a) When direct contact occurs, minute amounts may cause miosis, constriction of the pupils.
Pupils will not dilate (enlarge) in low ambient light as they would normally. Chemical alarms may not
detect the presence of nerve agents.

      (b) Exposure time required to cause miosis depends on the agent concentration and the
cumulative effects of repeated exposure.

       (c) Symptoms range from minimal to severe depending on agent’s concentration and duration
of exposure.

           1. Severe miosis may persist for 48 hours or longer after onset of exposure.

           2. Complete recovery may take up to 20 days or longer.

    (2) There will be some loss of night vision among personnel exposed. Refer all exposed personnel
to the flight surgeon immediately before performing flight duties or aircraft maintenance.

c. Exposure to bright light during night unaided flight. Sources of light can consist of but are not
limited to:

   (1) Aerial and ground flares, spotlights, vehicle headlights, search lights, and beacon lights.

   (2) Protective measures consist of turning the head away from the source, covering or closing one
eye, transfering the controls if copilot is available and not experiencing the same negative effects, or
changing aircraft heading if mission permits.

d. Over all protective methods used to protect night unaided vision from flight hazards and limitations
include:

   (1) Lowering of clear visor.

   (2) Adjusting cockpit lighting to lowest readable level.

   (3) Lowering the intensity of the aircraft’s interior and exterior lighting if mission permits.

   (4) Closing or covering one eye briefly when unexpectedly exposed to a bright light when flying
night unaided.

Example: Each eye dark-adapts independently. By closing or covering one eye, a large percentage of
the night visual acuity of the covered eye or closed eye.

   (5) Use supplemental oxygen if available when flying above 4,000 feet.
     Example: The onset of hypoxia and its adverse effects upon your night vision may occur as low as
     4,000 feet in altitude.

        (6) If mission permits, utilize search light or landing light.

        (7) Use BLPS (laser specific protective visors and goggles).

        (8) Gain distance from laser source and get out of the laser path.

        (9) Avoid brightly lit areas.

        (10) Use short ordinance burst (flash of bright light or tracer).

        (11) Nutrition: consume a balanced diet (vitamin A supplement).

        (12) Hydration: consume water; eyes need abundance of oxygen to function properly. Dehydration
     causes a decrease in fluid circulation, which reduces oxygen levels in blood stream. Dehydration can
     cause blurred vision and staring.


G.   ENABLING LEARNING OBJECTIVE
      ACTION:     Identify the effects of the self-imposed stresses.
      CONDITIONS:          Given a list of self-imposed stresses and their functions.
      STANDARDS:           IAW TC 3-04.93, FM 3-04.203, and AR 40-8.


1.   Discuss the effects of the self-imposed stresses

     a. Drugs.

        (1) Illness, degradation in motor skills, awareness level, and reaction time are all possible side
     effects related to drugs.

        (2) Refer to AR 40-8 for restrictions for drug use while on flying status. Self-medicating is not
     authorized; consult Flight Surgeon for approval of drug use (medications).

     b. Exhaustion.

         (1) Poor physical condition and exercise, lack of rest, and irregular sleeping patterns or habits are
     all contributing factors leading to exhaustion.

        (2) Common side effects related to exhaustion are altered concentration, awareness, attentiveness,
     increased drowsiness, and ineffective night vision viewing techniques (related to staring not scanning).

     c. Alcohol.

        (1) Long lasting physiological effects related to the consumption of alcohol.
        (2) Detrimental effects related to the consumption of alcohol include poor or altered abilities upon
     judgment, decision-making, perception, reaction time, coordination, and scanning techniques
     (tendency to stare at objects).

         (3) Histotoxic hypoxia is the saturation of tissue cells with alcohol or drugs causing interference
     with the use of oxygen (decreased tissue perfusion). The consumption of one ounce of alcohol places
     an individual at 2,000 feet physiologically.

     Example: AR 40-8 states that crew members will not perform flight duties within 12 hours of
     consuming an alcoholic beverage and then until there are no residual effects remaining.

     d. Tobacco smoking causes hypemic hypoxia, which is the greatest threat to night vision.

         (1) Effects of tobacco (smoking of cigarettes) are decreased night vision viewing capability by an
     average of 20 percent at sea level and increased chance of becoming a possible hypoxia casualty when
     flying at higher altitudes such as instrument training or other flights at altitudes up to 10,000 feet.

        (2) The physiologic effect at ground level is the same as flying at 5,000 feet.

        (3) Hypemic or anemic hypoxia is caused by the reduction of the oxygen carrying capability of the
     blood (via the red blood cells- RBCs). Carbon monoxide binds with the hemoglobin, not allowing or
     severely decreasing the amount of oxygen allowed to bind with the hemoglobin.

     Example: Carbon monoxide has an affinity for hemoglobin 200-300 times greater than oxygen.
     Smoking three cigarettes in rapid succession or 20 to 30 cigarettes within a 24-hour period will
     increase the carbon monoxide content of the blood 8 to 10 percent. Even more importantly, the
     smoker has lost approximately 20 percent of the night vision capability at sea level.

     e. Hypoglycemia and nutritional deficiency.

        (1) Effects of hypoglycemia and nutritional deficiency result in hunger pains, distractions,
     breakdown in habit patterns, and shortened attention span.

        (2) Contributing factors leading to low blood sugar (hypoglycemia) and nutritional deficiency are
     skipping, missing, or postponing meals.

        (3) Poor dieting can lead to Vitamin A deficiency, which hinders production of rhodopsin.
     Consumption of a balanced diet to produce the chemical rhodopsin should consist of the following
     foods: eggs, butter, cheese, liver, carrots, and most green leafy vegetables


H.   ENABLING LEARNING OBJECTIVE
      ACTION:      Identify the proper night viewing (scanning) techniques.
      CONDITIONS:           Given a list of proper night viewing (scanning) techniques.
      STANDARDS:            IAW TC 3-04.93 and FM 3-04.203.
1.   Discuss the proper night viewing (scanning) techniques.
     a. Scanning.

        (1) Stop-turn-stop-turn motion scanning technique should be used. For each stop, an area
     approximately 30 degrees wide should be scanned. The viewing angle includes an area approximately
     250 meters wide at a distance of 500 meters. The duration of each stop is based on the degree of detail
     that is required, but no stop should last longer than two to three seconds to prevent the rhodopsin from
     bleaching out the image.

         (2) Ten degree circular overlap viewing should be utilized when moving from one viewing point
     to the next. Crew members should overlap the previous field of view by ten degrees.

     b. Off-center viewing can be used to compensate for the night blind spot.

       (1) View an object by focusing ten degrees above, below, or to either side of the object in order to
     maintain visual reference of the object so as not to bleach it out and lose sight of the object.

        (2) Ten degree circular overlap and off-center viewing are used in combination when it comes to
     night unaided viewing.

     I.      ENABLING LEARNING OBJECTIVE
             ACTION:      Identify the physiological effects of night vision devices
                          (NVDs).
             CONDITIONS:          Given a list of physiological effects.
             STANDARDS:           IAW TC 3-04.93.


     1.        Discuss the physiological effects of night vision devices (NVDs).
               a. The immediate effects on unaided viewing after viewing through NVDs are decreased
               ability to perceive accurate depth perception, distance estimation, degree of contrast,
               discoloration of objects (chromatic), and the possibility of induced spatial disorientation.

                  b. Chromatic adaptation is a discoloration of objects viewed with the unaided eye after
                    viewing through NVDs (ANVIS) for an extended period of time. This is a normal
               physiological response. It causes no discomfort and will disappear or subside within three to
               five minutes on average. It will take this amount of time to regain your dark adaptation and
                       night vision acuity to the thirty to forty minute level-degree of effectiveness.

               c. Spatial disorientation maybe induced by the following:

                       (1) Aircraft bank greater than 30 degrees.

                      (2) A scanning technique consisting of rapid head movements.

                      (3) Unfamiliar perception related to lack of NVG experience.

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:24
posted:8/20/2011
language:English
pages:70