Mountain Flying Checkout
Peter Del Vecchio
Turning Base For Runway 18 at South Lake Tahoe
Completed by student before checkout:
1. Review of mountain flying notes (below)
o For further study (optional), see bibliography at end
2. Complete cross country flight plan and file with FSS
o Flight should include stops at three or more airports
o See “Preflight Preparation” below for calculations required and notes on
Completed together during checkout:
1. One hour of ground instruction
o Review of mountain flying notes, flight plan, preflight preparation
2. Flight to the mountains!
o Be sure to bring food, water, emergency gear, and a camera
o I’ll bring along a pulse oximeter so we can watch the effects of altitude on
your blood oxygen saturation and heart rate.
o Optional: We can use oxygen during the flight. West Valley has oxygen
tanks that club members can borrow. You’ll need to provide your own
mask or cannula.
o Optional: We can fly IFR into one of the airports. We can also fly IFR on
the way back.
3. Post flight review
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o Rising terrain on one side, drop-off after departure, sloping runway
o Campground on the field, scenic location, cheap fuel
o One of my favorite low-altitude stops
Blue Canyon (KBLU)
o Rising terrain, drop-off
o Not too much at the airport, but a very memorable approach and landing
South Lake Tahoe (KTVL)
o Common destination for summer and winter, long runway
o Good gumbo at Chase’s Bar & Grill on field
o Expensive fuel
o Common destination for winter sports, long runway, cheap fuel
Alpine County (Q82)
o Good for pilotage practice from Columbia
o Need to plan descent, very common to come in high
Grass Valley (O17)
o Sloping terrain, good intro airport, low altitude
o Common destination, good intro airport, low altitude
o Sloping terrain, good intro airport, low altitude
o Common destination, Class C
Lee Vining (O24)
o Narrow runway, good place to stop before/after crossing Yosemite
Final Approach to Runway 34 at Georgetown (Q61)
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Create a complete VFR cross country flight plan to destination airports
o Assume ½ hour at each airport for pattern work
o Assume an additional ½ hour (or more) at an airport if stopping for fuel,
food, bathroom, etc. (Plan to make at least one stop - it’s going to be a
o Be sure to plan descent into and out of destination airports.
The airplane’s performance will be greatly reduced, as compared
to sea level, and you’ll need to clear some very high terrain on the
climb out. Thus, you may not be able to go straight-line between
o Density altitude at target airports and along route
o Takeoff (ground roll/over 50’) and landing length (check airports)
o Climb rate at 8000’, 10000’, 12000’
Calculate climb rate at standard temperature, +10o C, and +20 o C
o A/FD entry for destination airports
In particular, note runway lengths/slopes, traffic pattern
directions/altitudes, noise abatement procedures, climb-out
o Obstructions and terrain near airports
o Communication procedures enroute and at destination airports
Open and close flight plan
We’ll open the flight plan upon departure for the home
Obtain flight following
Where available, we’ll get flight following.
CTAF, ASOS/AWOS, and tower communication
If instrument rated, review
o Approach plates for destination airports
o Departure procedures from destination airports
o Airways, intersections, and MEAs along route
o If desired, the flight from the home airport to the first mountain airport can
be done IFR. Likewise, the flight from the last airport back to the home
airport can be done IFR. All other legs should be VFR.
On the day of the flight
Weather, especially METARs, TAFs, FAs, and winds aloft
AIRMETs, SIGMETs, Convective SIGMETs
o File the flight plan with an FSS and obtain a weather briefing
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Mountain Flying Notes
Weather And Flight Planning
Mountain weather can change rapidly
o Check forecasts and contact Flight Watch (122.0) often
Colder temperatures greater chance for icing
Fly early in morning or late in afternoon for lightest winds.
VFR over high terrain may be impossible even though your departure and
destination airports are experiencing good weather.
The Colorado Pilots Association recommends flying with at least 15SM visibility.
Mountain flying is not a guaranteed go. Check the forecast, and then test the
waters. If you like what you see initially, proceed; if not, turn back. Don't become
too attached to completing your flight.
Don’t go if the weather is doubtful.
If stopping at multiple airports, use multiple flight plans. In general, if you’ll be
stopping at multiple airports on a flight, it’s a good idea to use multiple flight
plans. If your plane goes down in between two airports, search crews will have a
much better idea of where to look. Also, if one leg takes a bit more or less time
than planned, the clock is reset when you open your next flight plan.
Downdrafts & Updrafts, Turbulence, Rotors, Wind Shear
Make sure you know the winds aloft and at your destination airports.
o Try to plan your route so you are flying on upwind side of valleys and
o Always know where the wind is coming from.
Rotors and wind shear are basically guaranteed at 20 kts, especially on the lee
side of a peak/ridge.
Use visualization to determine possible downdraft areas. Air behaves like water.
Ask yourself, "What would water do if it were flowing like the winds aloft?”
The venturi effect in mountain passes can increase wind velocity significantly.
o This can produce winds in passes that are much stronger than winds aloft.
o Expect wind to be much greater velocity over mountain passes than
reported in areas a few miles away.
Winds aloft greater than 30 knots at cruise altitude usually means the novice pilot
should delay or postpone the flight until more favorable conditions prevail.
When approaching a ridge:
o Inbound: fly at 45 degree angle when ¼ to ½ mile out
o Outbound: fly straight out (90o angle), get away as quickly as possible
Downdrafts can be smooth or rapid/jolting monitor the VSI
o A typical downdraft will produce a 1000 to 1500 fpm descent
If caught in a downdraft
o Apply maximum power, lean (for best power)
o Do not pull up!
It’s very common for people to pull up and then stall or enter a
spin. People will often pull up and try to increase rate of turn by
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adding rudder. This is a perfect recipe for entering a spin at high
o Fly away at VA
This may increase rate of descent, but it will get you out of
downdraft as quickly as possible.
The further you are from a ridge, the less turbulence and
downdrafts you will experience.
o Downdrafts on lee side of mountain updrafts on windward
If you get caught in a downdraft, look for an area where the wind
may be rising.
Find rising air and then perform shallow turns to remain in the
o It may be necessary to fly toward a windward slope or some distance
downwind before the aircraft can establish a positive rate of climb.
o Most accidents caused by downdrafts are due to the pilot's concern about
Don’t try to out-climb a downdraft.
Instead, try to escape away from the ridge that is causing the
If lift (updrafts/downdrafts) is not a factor, fly on the appropriate side of the
valley so that your 180o exit turn can be made into the wind.
Establish 2000 to 3000' clearance over mountains
o Plan to cross mountains at least 2,000 feet above the highest point along
the route. This altitude should be reached well in advance, as some terrain
will rise faster than the aircraft climb rate.
Lenticular clouds extreme turbulence
o Can extend for tens or hundreds of miles
In heavy turbulence, fly an attitude and accept altitude loss
o Don't over-stress the airframe
Don't fly near or above abrupt changes of terrain such as cliffs or rugged areas.
Very dangerous turbulence may be expected, especially with high winds.
Don’t rely on cloud shadows for wind direction (unless you are flying at or near
the cloud bases). Expect the wind to be constantly changing in direction and
velocity because of modification by mountain ridges and canyons.
Don’t fly the middle of a canyon. This places you in a poor position to make a
turnaround and it subjects you to shear turbulence. Fly on the downwind side of
canyons to catch updrafts.
If you need to make a tight turn, slow down. Flying slower provides for a more
reaction time and a tighter turning radius.
There are three important factors that affect air density: altitude, temperature, and
Calculate density altitude before your flight.
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o Density altitude is the altitude the airplane thinks it is at and performs in
accordance with. High, hot, and humid conditions may raise the effective
physical altitude of an airstrip to a performance altitude many thousands
of feet higher than its actual elevation.
o Be familiar with the performance of your aircraft at altitude: service
ceiling, takeoff and landing distance, climb rate.
o The horsepower output of the engine is decreased because its fuel air
mixture intake is reduced.
Normally aspirated engines lose about 3 percent of their
horsepower for each 1,000 feet above sea level.
For a normally aspirated engine, the maximum power you can
generate at 7500’ is 75%.
o The propeller develops less thrust because the blades are less efficient.
o The wings develop less lift because the less dense atmosphere exerts less
force on the wings as airfoils.
o As a result, the takeoff distance is increased and the climb performance
Know the performance of your airplane:
o VY decreases with altitude. As a rule of thumb, subtract 1kt for every
1,000 feet of density altitude.
o VG decreases as weight decreases. As a rule of thumb, VG decreases 2kts
for every 10% under maximum gross weight.
o Weight and density altitude are the two most important factors when
considering the appropriate airspeed to fly for best rate of climb or best
glide. Learn to interpolate to figure the proper performance data before
you need it.
o Don't use short field flap settings for high density altitude takeoffs (unless
the field is truly short.) Short field flap settings offer a better angle, not
rate of climb. At the typically long high-elevation airports flaps will be a
hindrance to reaching VY more quickly.
A good way to compensate for lower power is to be light. As a rule of thumb,
being 10% under maximum gross weight provides a 20% performance benefit
over the POH numbers.
The visual aspects of mountain flying can be deceiving, but if you can see more
and more of the terrain on the other side of the ridge you are approaching, you are
higher than the ridge and can probably continue.
Plan every ridge crossing as though an engine failure was imminent.
From the Mountain Flying Bible:
o BASIC PREMISE #1 - Always remain in a position where you can turn
toward lowering terrain.
This axiom also encompasses the idea that you will not enter or fly
in a canyon where there is not sufficient room to turn around.
Another way of stating this truth is to have an escape route in mind
and be in a position to exercise this option.
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o BASIC PREMISE #2 - Do not fly beyond the point of no return.
This is the position when flying upslope terrain where, if you
reduce the throttle to idle and begin a normal glide, you will have
sufficient altitude to turn around without impacting the terrain.
o As you near the ridge, when arriving at a position where the power can be
reduced to idle and the airplane will glide to the top of the ridgeline, a
commitment to cross the ridge can be made. At this position, the airplane
is close enough to the ridgeline not to experience an unexpected downdraft
of a nature that will cause a problem. If a downdraft is encountered, keep
the power on, lower the nose to maintain airspeed and the airplane will
clear the ridge.
Realize that the actual horizon is near the base of the mountains. This mistake of
using the summit of the peaks as the horizon will result in the aircraft being
placed in an attitude of constant climb. This could inadvertently lead to stall from
which a recovery may be impossible.
Landing at a short mountain strip requires exact airspeed control to eliminate
float. A 10% increase in the proper approach speed results in a 21% increase in
Make sure to richen mixture for go-around
o Momentarily increase to full power when close to pattern altitude, but
makes sure you have enough time to loose the airspeed you’ve gained.
Richen to 50o – 100o rich of peak EGT. (50o is good for small engines,
100o good for high performance)
o Depending on your altitude, cruise power at high elevation is likely to also
be maximum power. If this is the case, your fuel-air mixture is already
properly set and requires no adjustment for landing.
o See your airplane’s POH for the manufacturer’s recommended leaning
Colorado Pilots Association: "The most common problem for flatlanders is the
tendency to fly the approach below the normal indicated airspeed for landing.
Thus, an area of heavy emphasis for mountain flying is to fly by the numbers and
approach to land at the normal indicated airspeed."
For safety from eddies, wind shear, and gusty conditions, plan your approach
using the runway numbers as your aim point, flare 500 feet down the runway, and
try to touch down on the 1,000 ft. marks. High altitude runways are quite long and
this provides insurance in case of a severe downdraft.
Be certain to use the same indicated airspeed at high-altitude airports that you use
at low-altitude or sea level airports for the takeoff or for the approach to landing.
When flying to remote airports, before landing, first overfly the field to check for
wildlife and runway conditions.
If you haven’t landed by ½-way down the runway, you should abort the landing.
o You’ll look high due to narrow runways
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o Your eyes tend to focus on rising terrain/ridges. This will cause you to
come in high if a hill is near the runway.
o Sloping runways are common in mountains
This can create illusions of being too high (upside) or too low
The slope will also affect takeoff and landing distance. This can
be a very significant important factor at mountain airports.
Ground Speed & TAS vs. IAS
Roughly, the TAS increases by 2% over IAS for every thousand feet altitude gain.
o This implies that at 10,000’ the TAS will be about 20% higher (if
calculated accurately it’s actually closer to 15%)
o This is a built-in compensator for reduced lift caused by the thin air at
higher altitude airports.
Ground speed will be much higher, visual queues will be very different.
Since TAS is higher, you’ll need to fly pattern wider than normal.
Before landing at a mountain airport, make sure you can climb back out. One
technique you can use is to overfly the field at, say, 1500 feet AGL and apply full
power. If you don’t achieve at least 300fpm climb rate, you probably shouldn’t
A rule-of-thumb for operating from a short runway is that if you obtain 71% of
the speed necessary for rotation at the ½-way point of the runway, you can take
off in the remaining distance.
o Calculate this speed beforehand and review it as part of your pre-takeoff
o E.g. VR=55kts need to obtain 39kts at ½-way point.
o The ½-way point should be treated as a solid abort point.
Before takeoff, you must lean for max power
o For a plane with a direct drive engine and a fixed pitch propeller, before
takeoff, hold the brakes, apply full throttle, lean to peak RPM (or 50o –
100o rich of peak EGT). Leave mixture at that position and accomplish
o For a plane with a constant speed propeller, leaning is normally done
using the EGT. See your POH for the manufacturer’s recommendation.
The takeoff distance varies with the gross weight. A 10% increase in the takeoff
gross weight will cause:
o 5% increase in speed required for takeoff.
o 9% decrease in acceleration (from stop to takeoff speed).
o 21% increase in takeoff distance.
Thus, you may not want full fuel on takeoff from a high-altitude airport.
o A good "rule of thumb" for the pilot to remember is - for each thousand
feet above sea level, the takeoff run increases approximately 25 percent.
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o In the case of normally aspirated engines (not turbocharged or
supercharged), at an altitude of 10,000 feet, about one-half of available
engine horsepower is lost.
o Denver, Colorado: field elevation indicated on the altimeter is 5000 ft;
Summer day 80o F density altitude is 7500 feet the takeoff distance
at this density altitude will be 2.3 times the sea level takeoff roll.
The double whammy: not only must the airplane be at a higher true airspeed to
achieve flying speed, but it must do so with an engine that's not capable of
making sea level horsepower.
Note that density altitude can be much higher than indicated – the effect of
altitude on your body depends on the partial pressure of oxygen.
o Note that altimeters show pressure altitude (corrected for local altimeter
The U.S. Air Force recommends using oxygen starting at 8000ft.
o No O2 required until 12500 (although not required, it is recommended)
o Between 12500 and 14000, after ½ hour
o Higher than 14000, continuous
o Higher than 15000, must be provided for passengers
Night vision is inhibited above 5000’ pressure altitude.
Cannulas can't be used above 18000'
o Manufacturers prohibit use above this altitude.
o Above this altitude, up to 25,000’ you can use an oxygen mask.
Regulator and flow meters fail, valves freeze, and lines plug up, so always be
prepared to descend.
o It may make sense, because of the increased rick, to plan a flight at, say,
16,000’ vs. 22,000’.
o The time of useful consciousness at 20,000’ is 30 minutes; once you get
higher it drops precipitously. At 22,000’, the time of useful consciousness
is about 10 minutes.
o Time of useful consciousness is sometimes also referred to as EPT, or
Effective Performance Time.
Oxygen bottles are normally low pressure, 500 PSI, or high pressure, 1800 PSI.
o The most common is the 1800 PSI variety. The 1800 PSI bottles are
o Oxygen bottles need to be re-certified every 5 years.
o The chart below shows the % capacity remaining with various pressures in
an 1800 PSI oxygen bottle.
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Use of pulse oximeter, from http://www.flightstat.nonin.com/Hypoxia.pdf:
o It is a good idea to consider oxygen for flights above 5,000 feet at night
and above 8,000 feet during the day. If oxygen use is anticipated, place the
nasal cannula or face mask on and start the oxygen flow when climbing
through 5,000 feet. Initially, set the flow to the altitude to which you will
be climbing and check your oxygen saturation after level off. If your
reading is below 92-93%, increase the flow until the desired reading is
obtained. Check your blood oxygen saturation at 10-15-minute intervals
during the flight to determine if your oxygen flow is sufficient. At night,
or during flights that are stressful such as in IFR conditions, increase the
oxygen flow until a saturation of 94-95% is achieved. Since workload is
heaviest during the descent and approach, especially during the night IFR,
remain on oxygen until you are on the ground.
More on pulse oximetry from http://www.radialsolutions.com/
o What is oxygen saturation?
Oxygen from the air that we breathe is carried around the body bound to
the hemoglobin in our red blood cells. Oxygen saturation is the percent of
hemoglobin that is fully saturated with oxygen. A healthy person,
breathing air at sea level, would have a saturation of 96% to 98%.
o How is oxygen saturation measured?
The technology is called "pulse oximetry". It was first developed, in fact,
for aviators back in the 1940s but it took the arrival of microprocessors to
make it practical and universally available. The pulse oximeter shines two
different light sources (red and infrared) through the finger. Each light has
a different absorption characteristic for oxyhemoglobin (the red, saturated
blood) and deoxyhemoglobin (the blue, unsaturated blood). The oximeter
then measures the ratio (percent) of saturated to unsaturated hemoglobin.
o What does oxygen saturation tell you?
Oxygen saturation tells you exactly how much oxygen is available for the
body to use. Healthy people function at oxygen saturation levels in the
high nineties as noted above. As saturation falls to the low nineties, most
of us would be aware of "feeling different" as the first symptoms of
hypoxia appear. These are quite variable from person to person but include
such things as lightheadedness, lip tingling, night vision deterioration,
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increased heart and respiratory rate, and mild memory impairment.
Saturation levels of 90% or below are usually an indication for
supplemental oxygen therapy.
A general rule-of-thumb for using a pulse oximeter is to never let your oxygen
saturation level get more than 10 percentage points below your home (ground
level) saturation level.
Don’t choose a route that would prevent a suitable forced-landing area
In the event of a forced landing, approach at best glide, but touch down / impact at
Don’t leave the airplane without a compelling reason if you have executed an
emergency or precautionary landing. Temporary evacuation may be necessary if a
fire hazard exists.
If you have a choice between landing in light green trees or dark green, head
toward the light. Light green trees are more pliable, younger than dark green
Don’t land in water. You’ll flip upside down and, since the plane won’t be
visible, it’s less likely than you’ll be found. Also, mountain water is cold and you
could contract hypothermia.
Follow roads whenever possible.
Avoid flying over open water (Lake Tahoe, e.g.).
Plan your trip along routes that include populated areas and well-known passes, or
over valleys whenever possible.
Swaths cut through trees are usually power lines. It’s usually best to avoid them.
o Learn how to turn it on.
o The ELT may not turn on automatically in a forced landing, so you may
need to arm it manually.
Everyone flying in the mountains will encounter situations when it becomes
necessary to make a 180o turn. To turn around, slow down. This will decrease the
radius of turn. Pull back on the control wheel to trade airspeed for altitude if you
have extra speed. Then make the steepest turn you can comfortably make, up to
To execute a course reversal in IMC and wind up over the same spot, turn 90o
followed by 270o (an 80/260 also works).
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Blankets or sleeping bags
Wear or bring shoes you can use for hiking
Always bring emergency gear when flying in the mountains.
For Further Study
Books by Sparky Imeson
o “The Mountain Flying Bible”
o “The Shirt Pocket Mountain Flying Guide”
o Order them here: https://secure.airbase1.com/mtnflying/orders.asp
"Hypoxia, Oxygen and Pulse Oximetry," Furgang, Fred, MD.
Pulse Oximetry and the Oxyhemoglobin Dissociation Curve
Review of the Nonin Onyx Pulse Oximeter
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