Aviation 128 Aviation Safety and Security

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					        Aviation 128
Aviation Safety and Security
         Spring 2010
          Lesson 6
               Announcements
• Returning quiz 2 today
• Homework 1, extra credit due today
• Blackboard login method




Aviation 128     Aviation Safety and Security   2
Spring 2010
               Recap events
• Palo Alto GA crash last week
     – NTSB preliminary report has been filed
• Last class, National Airspace System
  Plan
     – Communications
     – Navigation
     – Surveillance
     – Weather automation
     – Avionics

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Spring 2010
                        Today
• Finish Ch. 8: more about Air Traffic
  Safety Systems
     – NAS modernization operational planning
     – Free Flight, its implementation timeline
• Begin Ch. 9: Aircraft Safety Systems




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         Traffic flow management
• Centralized at ATC system command
  center (ATCSCC)
     – Some functions distributed to ARTCCs,
       TRACON, and high-activity ATCTs.
• NAS-wide information service
     – Systemwide computer network
     – Standardized data formats
     – Interoperable applications

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Spring 2010
  NAS-wide information service
• Allows data exchange b/t users and
  FAA
• Everyone has a common view of the
  NAS for better decision making during
  all phases of flight, including planning.




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Spring 2010
                Flight Object
• To replace the flight plan
• Dynamically update and make available
  to NAS service providers and users
• Flight object contains
     – User’s route and altitude preferences
     – A/c weight
     – Gate assignments
     – Departure/arrival runway preferences
     – Location while in flight
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Spring 2010
        Purpose of improvements
• Goal of operational planning upgrades:
  integrate operational and business
  decisions for more
     – Efficiency
     – Predictability
     – Flexibility
• 100,000 flights use NAS daily -- lot of
  decisions to be made!

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Spring 2010
               Uses in flight planning
• Predict locations
• Predict impact of traffic demand and weather
  along route
• During flight, updates on weather, NAS status
  info to airlines and operational centers
• New tools will eventually help plan direct flight
  paths, sequence departures and arrivals,
  change routes, balance capacity


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               TFM will modernize…
• Infrastructure
• Data exchange and collaboration
  process
• NAS analysis and prediction tools




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                       ETMS
• Enhanced traffic management system
• Currently exists to track, predict, and
  manage traffic flows
• Upgrade of h/w and s/w
     – Workstations, computers, peripherals
     – Proprietary software
• Control-by-time-of-arrival (CTA) toll
     – To manage arrival demand

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Spring 2010
    Flight Service Improvements
• FSS modernization will get operational and
  supportability implementation system
  (OASIS)
• Combines functions of
     – Direct user access terminal (DUAT)
     – Graphics weather display system (GWDS)
• OASIS lets pilots file flight plans (like DUAT)
• Later OASIS will be integrated with the NAS-
  wide info svc to get weather and NOTAMs.

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Spring 2010
        Airport surface operations
• A/c and surface vehicles (fuel trucks,
  service vehicles, luggage carriers)
• Currently ATCT has minimal automation
  support
     – Relies on visual and voice comms
• Accurate and complete info on a/c and
  vehicle location and intentions is
  needed
     – Especially nighttime, low-visibility

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Spring 2010
      Surface ops improvements
• Decision support tools, comm/surveillance
  technology, new procedures and training
• Surface Movement Advisor (SMA)
     – Shares info b/t FAA, airline ramp control ops, and
       airport mgmt.
     – Datalinks to convey routine info.
     – Surveillance to reduce runway incursions
     – Improved radar displays
     – Improved traffic displays, weather info, decision
       support tools

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Spring 2010
                 SMA rollout
• Initially at select airports for ramp
  control ops to have arrival/departure
  info.
• Airport movement area safety system
  (AMASS) at busiest airports
     – Support surveillance
     – Compares track of a/c on final approach
       with surface vehicles as detected by radar
     – Predict conflicts, alert controllers

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Spring 2010
               Runway incursion
• A top 5 priority for FAA
• AMASS and other tools address this
  issue
     – Additional surveillance
     – ATC tools
     – Signage, lighting
     – New procedures
     – Increased training

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Spring 2010
  Surface Management System
• Evolved from SMA prototype in Atlanta
• Provides airport config, a/c arrival/departure
  status, ground movement advisories to
  controllers
• SMS interface with AMASS to coordinate
  arr/dep flows with surface activity
• Enhanced SMS give users access to flight
  planning, traffic mgmt, etc., plus a “look-
  ahead” prediction feature

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Spring 2010
               Departures & Arrivals
• Two-pronged approach to airport
  congestion
     – Modern technology
     – More runways
• A/c are sequenced in and out of airport
  by TRACON controllers.
     – Improved tools for precise spacing,
       sequencing

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Spring 2010
 Dep/arr control enhancements
•   On-screen weather display
•   Improved sequencing & spacing tools
•   Information sharing with users
•   Info sharing b/t terminal and en route
•   Support for flexible arr/dep routes




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Spring 2010
    Terminal modernization plan
• Installation of STARS
• Standard terminal automation
  replacement system
• Digital integrated computer system with
  modern color displays, distributed
  processing networks.
• Upgradeable


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Spring 2010
               Future STARS
• Display airport surface traffic, runway
  incursion alerts
• Interface for terminal CPDLC
• Interface with advanced c/n/s and
  weather systems
• Interface with AMASS



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Spring 2010
               En route and oceanic
• Existing automation system must be
  replaced before new applications, Free
  Flight can be provided.
• En route and oceanic are colocated but
  have different systems
     – B/c of lack of surveillance & direct comms
       over oceans.
• Oceanic surveillance and direct comms
  will make comparable to en route

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Spring 2010
                En route
• A/c currently monitored by radar
• Follow fixed route of airways (not direct
  route or favorable winds)
• Oceanic a/c follow “tracks” aligned with
  winds daily




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Spring 2010
               Modernization will
• Replace en route controller displays
• Replace en route and oceanic
  computers with standard h/w
• Replace applications s/w with
     – Controller decision support tools
     – Advanced surv and comm info methods
     – Integrate with NAS-wide info svc to help
       with data-sharing

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Spring 2010
                      Free Flight
• Current air traffic restrictions
     –   Ensure separation
     –   Prevent airports being over capacity
     –   Special-use airspace
     –   Ensure safety of flight
• Free Flight: safe and efficient operating ability
  under IFR
     – Operators select their path and speed in real-time
• Economically-driven

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Spring 2010
               Free Flight concept
• Every a/c has protected layers of
  airspace around it
• A/c can freely move in any direction,
  altitude at any time subject to these
  protected layers
• Air traffic managers intervene if critical
  boundaries violated
• Extension of National Route Program
  (NRP)
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Spring 2010
               Free flight outcome
     –   Decrease user costs
     –   Improve airspace flexibility
     –   Remove flight restrictions
     –   Save fuel
     –   Reduce delays, and more
• Principles
     –   Must not compromise safety
     –   Benefits-driven
     –   Collaborative planning
     –   Address human-factors
     –   Accommodate users with different equipage
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Spring 2010
               Free Flight Phase 1
• Core Capabilities Limited Deployment
• Phase 1 objective is to mitigate NAS
  modernization risks by deployment,
  testing
     – Evaluate performance, training procedures,
       safety issues.
     – Users and svc providers assess
       performance, benefits, and safety before
       further deployment
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Spring 2010
           Phase 1 tools deployed
• User Request Evaluation Tool (URET)
• Traffic Management Advisor (TMA)
     – Of Center TRACON Automation Sys CTAS
• Passive Final Approach Spacing Tool
  (pFAST)
     – Of Center TRACON Automation Sys CTAS
• Surface Movement Advisor (SMA)
• Collaborative Decision Making (CDM)
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Spring 2010
        How FF Phase 1 behaves
• Operationally similar to NRP
     – Users above FL 290 (29000 ft) can elect to
       fly off-airway least-time tracks between
       departure, arrival.
     – However, must have constant altitude.
• No special avionics or user
  preclearance


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Spring 2010
    NAS Modernization Timeline
• Phase 1 (1998-2002)
     – Host/oceanic computer system replacement
       (HOCSR) were IBM systems to replace old
       ARTCC computers - done
     – Display system replacement (DSR) gives ARTCC
       en route controllers large color displays (running
       Windows) - done
     – STARS - new computers and displays for facilities
       handling traffic within 50 mi of airport - final stages
     – URET partially operational at certain airports
     – ATCSCC established in Va.
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Spring 2010
    Ongoing NAS modernization
• For Phases 2 and 3 as they are called in
  book,
     – Timings and emphasized programs in real life do
       not always correspond
• To stay current, go to the FAA website
• http://nasea.faa.gov
• http://www.faa.gov/about/office_org/headquar
  ters_offices/ato/service_units/operations/syse
  ngsaf/cip/files/CIP_FY09-13_Complete.pdf

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Spring 2010
               NAS and ATC Funding
• Modernization necessary but very expensive
     – 100s of millions to billions of $
• FAA depends on Congress to approve funds
  yearly
     –   Part of DOT package
     –   Goes to OMB
     –   To President, who submits to Congress
     –   Congressional committees review, hold hearings
• Two years from start to finish
• Then FAA can start procuring, constructing

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Spring 2010
           Aircraft Safety Systems
• How technology and technology of design
  tools have contributed to jet transport safety
  record
• New technologies that further improve safety
  and efficiency
• Current a/c complex, sophisticated
     – Automated tasks
     – Fly-by-wire (electronic control from wheel to flight
       controls)
     – Protections prevent pilot from exceeding limits
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Spring 2010
               Historical overview
• Before WWII, prop-driven reciprocating
  engines
• WWII brought about jet engine, radar,
  wing sweep
     – Challenge was need for high-speed, high-
       alt operation
• Safety-of-flight issues in the early jet
  transport era (Boeing B-47 and Dash
  80)

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Spring 2010
               Jet engine developers
• Frank Whittle (UK) and Hans von Ohain
  (Germany)
• GE used Whittle’s work for USAF
     – J-47 axial flow in the F-86 and B-47
• Westinghouse for Navy
• Pratt&Whitney J-57 on B-52 and 707



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Spring 2010
     Jet engine problems solved
• Fuel consumption, noise, reliability,
  durability, stability, thrust.
     – Piston engines had problems at increased
       size and power.
• Jet propulsion efficiency increases with
  airspeed
     – Opposite of propellers.
     – Specific fuel consumption has dropped with
       time.
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Spring 2010
       Demands on jets in last 30
               years
• Changing, more stringent demands for
     – thrust, payload.
     – less noise
• Reliability and safety have improved.
     – In-flight shutdown rate (IFSD)
     – Failure mode (unplanned) of passive failure or disk
       rupture. Fix: pod-mounted installation.
     – Computer and sensors for real-time monitoring
• IFSD dropped significantly in last 15 yrs, a
  joint effort.
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Spring 2010
         Long-range transport era
• Commercial transport leaps forward with
  Boeing B-47
     – High sweep/AR/wing loading, thin wings
     – range of speeds, long duration, high-alt
     – Pod-mounted engines
• Safety issues
     – How to take off and land
     – Stopping distance
     – Control system ability over large speed range,
       flutter
     – Structural integrity for planform and speed range
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Spring 2010
               High-lift systems
• TE flaps for takeoff climbout, but low-
  drag bad for approach
• Multi-element slotted TE flaps
• LE flaps for greater safety - better
  takeoff and landing field length, more
  stall margin
• High-camber airfoil via slats
• High LE camber outboard for stable and
  better stall characteristics
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Spring 2010
        Stopping systems (1 of 2)
• Antiskid system: make brakes effective on
  short slippery runways
     – Challenge of multi-wheel main gears
     – Later, independent wheel control
     – Digital microprocessor antiskid today
• Fuse plugs: prevent tire explosion from
  severe heating
     – Encountered when braking after refused takeoff
       (RTO)
     – low-melting-point plugs in tires allow for deflation
       before explosion

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Spring 2010
        Stopping systems (2 of 2)
• Speed brakes aka wing spoilers: provide
  downward load on main wheels
     – Needed to make main wheel brakes more
       effective
     – Automatically deployed spoilers
     – Sequencing of spanwise spoilers prevents pitchup
• Thrust reversers: for jet ops into regional
  airports (e.g., 737-200)
     – Not FAA-required so a/c must be able to stop
       without them
     – Still, helpful to divert exhaust gases forward so
       that thrust vector points aft
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Spring 2010
               Flying qualities
• Stability and control of airplane design
  are among most important for safety
• Extensive simulation: Models of the
  dynamic response, atmosphere go into
  flight simulators.




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Spring 2010
               Powered controls
• Closed-loop (automatic feedback)
• Hydraulic systems on B-47
     – Reliable, redundant
• Dash 80 combined aileron+spoiler control
• Vortex generators: reduce adverse shock
  near Mach 1
• Swept wing has different Dutch-roll
  characteristic from straight wing
     – Electromechanical yaw damper

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Spring 2010
               Low-speed stall
• High-lift systems need safe takeoff/landing
  margins
• Airfoil, wing twist, LE/TE flaps design
  adjusted
     – Wind tunnels
     – Flight tests
     – Nowadays, computational fluid dynamics (CFD)
• Early designs had adequate stall warning in
  dynamic response.
     – Stick-shaker and auto slat gapper effective
     – Simulators help greatly.
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Spring 2010
               Structural integrity
• Fracture-mechanics problems
     – Fuselage and skin fatigue
• Commercial a/c experience higher flight hours
  at lower stress levels.
• Tensile strength of aluminum that has been
  affected by a crack
     – Testing *after* sustaining fatigue, corrosion, or use
       damage.
• Electron microscope technology - shows
  crack growth
     – Growth rate depends on loading
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Spring 2010
               Structural Safety
• Excellent safety records via
     – Design, manufacture, maintenance, and
       inspection procedures
• System participants
     – Airplane manufacturers
     – Airlines
     – Airworthiness authorities
• Jet transports designed to be damage
  tolerant
     – In 1950-60s standard was to be fail-safe
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Spring 2010
                  Aging aircraft
• A/c operating near or beyond originally
  projected calendar years, flight cycles, or
  flight hours.
     – 20 years usually design goal (not officially in FAR)
• Fail-safe: residual strength after complete
  failure or obvious partial failure of a single
  principal structural element
• Damage tolerance (fail-safe) rule of 1978
     – Supplemental inspection documents (SIDs)


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Spring 2010
         Fatigue-initiated damage
• Primary cause of concern for aging craft
• Increases with flight hours, flight cycles.
     – Fuselage: pressure cycle of each flight
     – Wings: ground-air-ground cycle,
       maneuvers, turbulence.
• Probabilistic
     – Chance increases with time
     – Detection also a probability

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Spring 2010
                  Crack growth
• Example: fuselage
     – Cracks start at edge of fastener holes
     – Small cracks link to forma patch
     – Patch become long enough to be detected
• Rapid growth
     – Uncontrolled crack propagation
     – Will slow if crack turning occurs
• Multiple site damage (tear straps and
  adjacent bays)
     – How to determine age (in flight hours/cycles) of
       MSD onset.
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Spring 2010
 Technical issues in aging (1 of
               2)
• MSD: Condition of widespread cracking
  of structure
     – Neither fail-safe nor damage-tolerant
     – Multiple-load-path, crack-arrest features
       cannot guarantee protection from MSD.
• Corrosion: time-dependent decrease of
  structural element size
     – Higher stresses, lower structural margins
     – Hand in hand with factors leading to cracks

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Spring 2010
 Technical issues in aging (2 of
               2)
• Nondestructive inspection
     – Key for health assessment
     – Do not rely on for continued airworthiness
       of a/c near threshold of MSD.
• Structural repairs
     – Regain static strength, but may not fill
       damage tolerance, fail-safe requirements
• Terminating actions
     – Structural actions needed to eliminate MSD

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Spring 2010
               Aging and Finance
• No link has been found between aging
  aircraft, increased risk of safety, and
  deregulation
• Airworthiness Assurance Task Force
     – Made recommendations for older a/c
       maintenance, part replacement
     – FAA has adopted the recs.
• New orders being placed.
• FAA strained to make sure maintenance,
  replacement carried out on schedule.

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Spring 2010