Mountain Flying
How NOT to die…
Mountain Flying
Mountain Flying
• Weather and Flight Planning
– Downdrafts & Updrafts
– Turbulence, Rotors, Wind Shear
– Density Altitude
• Clearing Mountains
• Landing
• Ground Speed & TAS vs. IAS
Mountain Flying
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Takeoff Distance
Oxygen
Forced Landings
Course Reversal
Emergency Gear
Controlled Flight into Terrain (CFIT)
Weather and Flight Planning
Mountain weather can change rapidly
Check forecasts
Contact Flight Watch (122.0) often
Colder temps  greater chance for icing
Fly early morning or late afternoon for
lightest winds.
Weather and Flight Planning
 VFR over high terrain may be impossible
Even though your departure/destination
airports are experiencing good weather.
Colorado Pilots Association recommends
at least 15 Miles visibility.
Weather and Flight Planning
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.
Weather and Flight Planning
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.
If one leg takes a bit more or less time than
planned, the clock is reset when you open your next
flight plan.
Weather and Flight Planning
Make sure you know the winds aloft and
at your destination airports.
Try to plan your route so you are flying on
upwind side of valleys and canyons.
Always know where the wind is coming
from.
Weather and Flight Planning
Rotors/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?”
Weather and Flight Planning
The venturi effect in mountain passes can
increase wind velocity significantly.
This can produce winds in passes that are
much stronger than winds aloft.
Expect wind to be much greater velocity over
mountain passes than reported in areas a
few miles away.
Weather and Flight Planning
 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.
Weather and Flight Planning
When approaching a ridge:
Inbound: fly at 45 degree angle when ¼ to
½ mile out
Outbound: fly straight out (90˚ angle)
get away as quickly as possible
Downdrafts can be smooth or rapid/jolting
Monitor the VSI
A typical downdraft will produce a 1000 to
1500 fpm descent
Weather and Flight Planning
If caught in a downdraft
Apply max power, Lean (for best power)
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 adding rudder.
This is a perfect recipe for entering a spin at
high altitudes.
Weather and Flight Planning
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.
Weather and Flight Planning
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 updraft.
It may be necessary to fly toward a
windward slope or some distance
downwind before the aircraft can establish
a positive rate of climb.
Weather and Flight Planning
Most accidents caused by downdrafts are
due to the pilot's concern about altitude
loss.
Don’t try to out-climb a downdraft.
Instead, try to escape away from the ridge
that is causing the downdraft.
Weather and Flight Planning
If lift (updrafts/downdrafts) is not a factor,
fly on the appropriate side of the valley so
that your 180˚ exit turn can be made into
the wind.
Weather and Flight Planning
Establish 2000 to 3000' clearance over
mountains
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.
Weather and Flight Planning
Lenticular clouds = extreme turbulence
Mountain waves can extend for tens or
hundreds of miles
In heavy turbulence, fly an attitude and
accept altitude loss
Don't over-stress the airframe
Weather and Flight Planning
Don’t rely on cloud shadows for wind
direction
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.
Weather and Flight Planning
If you need to make a tight turn slow
down.
Flying slower provides for a more reaction
time and a tighter turning radius.
Weather and Flight Planning
There are three important factors that
affect air density: altitude, temperature,
and humidity.
Weather and Flight Planning
 Calculate density altitude before your flight.
 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.
 Be familiar with the performance of your aircraft at altitude: service ceiling,
takeoff and landing distance, climb rate.
 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%.
 The propeller develops less thrust because the blades are less efficient.
 The wings develop less lift because the less dense atmosphere exerts less force
on the wings as airfoils. As a result, the takeoff distance is increased and the
climb performance reduced.
Weather and Flight Planning
 Know the performance of your airplane:
 VY decreases with altitude.
 As a rule of thumb, subtract 1kt for every 1,000 feet of density altitude.
 VG decreases as weight decreases.
 As a rule of thumb, VG decreases 2kts for every 10% under maximum gross
weight.
 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.
 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.
Weather and Flight Planning
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.
Clearing Mountains
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.
Clearing Mountains
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.
• Sparky Imeson “The Mountain Flying Bible”
Clearing Mountains
 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.
 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.
• Sparky Imeson “The Mountain Flying Bible”
Clearing Mountains
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
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 landing
distance.
Landing
 Make sure to richen mixture for go-around
 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 50˚ – 100 ˚ rich of peak EGT.
 (50 ˚ is good for small engines, 100 ˚ good for high performance)
 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.
 See your airplane’s POH for the manufacturer’s
recommended leaning procedures.
Landing
"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.“
- Colorado Pilots Association
Landing
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.
Landing
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.
Landing
Runway Illusions:
You’ll look high due to narrow runways
Your eyes tend to focus on rising
terrain/ridges.
This will cause you to come in high if a hill is
near the runway.
Landing
Sloping runways are common in
mountains
This can create illusions of being too high
(upside) or too low (downslope)
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.
This implies that at 10,000’ the TAS will be about
20% higher (if calculated accurately it’s actually
closer to 15%)
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.
Takeoff Distance
 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 land.
 A rule-of-thumb for operating from a short runway is that if
you obtain 71% of the speed necessary for rotation at the ½way point of the runway, you can take off in the remaining
distance.
 Calculate this speed beforehand and review it as part of your pretakeoff briefing.
 E.g. VR=55kts - need to obtain 39kts at ½-way point.
 The ½-way point should be treated as a solid abort point.
Takeoff Distance
Before takeoff, you must lean for max power
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 50˚ – 100 ˚
rich of peak EGT).
Leave mixture at that position and accomplish the takeoff.
For a plane with a constant speed propeller, leaning
is normally done using the EGT.
See your POH for the manufacturer’s recommendation.
Takeoff Distance
The takeoff distance varies with the gross
weight.
A 10% increase in gross weight will cause:
5% increase in speed required for takeoff.
9% decrease in acceleration (from stop to takeoff
speed).
21% increase in takeoff distance.
You may not want full fuel on takeoff from
a high-altitude airport.
Takeoff Distance
 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.
 In the case of normally aspirated engines (not turbocharged
or supercharged), at an altitude of 10,000 feet, about onehalf of available engine horsepower is lost.
 Example: Denver, Colorado: field elevation indicated on the
altimeter is 5000 ft; Summer day 80˚F
 density altitude is 7500 feet
 the takeoff distance 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.
Oxygen
 Density altitude can be much higher than indicated
 The effect of altitude on your body depends on the partial
pressure of oxygen.
 Note that altimeters show pressure altitude (corrected for
local altimeter setting).
 The U.S. Air Force recommends using oxygen starting
at 8000ft.
 FAA regulations
 No O2 required until 12500 (although not required, it is
recommended)
 Between 12500 and 14000, after ½ hour
 Higher than 14000, continuous
 Higher than 15000, must be provided for passengers
Oxygen
 Night vision is inhibited above 5000’ pressure altitude.
 Cannulas can't be used above 18000'
 Manufacturers prohibit use above this altitude.
 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.
 It may make sense, because of the increased risk, to plan a flight at, say,
16,000’ vs. 22,000’.
 The time of useful consciousness at 20,000’ is 30 minutes
 At 22,000’, the time of useful consciousness is about 10
minutes.
 Time of useful consciousness is sometimes also referred to as EPT, or
Effective Performance Time.
Oxygen
Oxygen bottles are normally low pressure
500 PSI, or high pressure
1800 PSI is the most common variety.
The 1800 PSI bottles are green.
Oxygen bottles need to be re-certified
every 5 years.
Oxygen
It is a good idea to consider oxygen for flights
above 5,000 feet at night and above 8,000 feet
during the day.
Use of pulse oximeter
http://www.flightstat.nonin.com/Hypoxia.pdf
 http://www.radialsolutions.com/
 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.
Forced Landings
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 stall
speed.
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.
Forced Landings
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 trees.
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.
Forced Landings
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.
Forced Landings
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.
Forced Landings
ELT
Learn how to turn it on.
The ELT may not turn on automatically in a
forced landing, so you may need to arm it
manually.
Course Reversal
Everyone flying in the mountains will encounter
situations when it becomes necessary to make
a 180˚ 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 60 degrees.
To execute a course reversal in IMC and end up
over the same spot turn 90˚ followed by 270˚
an 80˚ /260˚ also works
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Emergency Gear
Warm clothes
Blankets or sleeping bags
Food
Water
Flashlights
Fire starter
Radio
Signaling mirror
Maps
Compass
Wear or bring shoes you can use for hiking
 Always bring emergency gear when flying in the mountains.
Controlled Flight Into Terrain
Controlled Flight into Terrain (CFIT)
occurs when an airworthy aircraft under
the control of a pilot is inadvertently flown
into terrain, water, or an obstacle with
inadequate awareness on the part of the
pilot of the impending disaster.
Cumulo-granite
Controlled Flight Into Terrain
 Accidents occur most frequently in GA operations
 4.7% of all GA accidents and 32% of GA accidents in IMC.
 On average there are 1.4 fatalities per CFIT accident, versus
0.33 fatalities per GA accident overall.
 17% of all GA fatalities are due to CFIT
 CFIT accidents are fatal 58% of the time.
 CFIT accidents occur 64% of the time in daytime and
36% at night
 51% of CFIT accidents occur in IMC, 48% in VMC and
1% unknown.
 Impacted terrain was flat 45% and mountainous 55%.
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Controlled
Flight
Into
Terrain
NTSB Identification: DEN07FA054
14 CFR Part 91: General Aviation
Accident occurred Wednesday, January 17, 2007 in Centennial, WY
Aircraft: Piper PA-28-180, registration: N43630
Injuries: 3 Fatal.
This is preliminary information, subject to change, and may contain errors. Any errors
in this report will be corrected when the final report has been completed.
•
On January 17, 2007, approximately 2215 mountain standard time, a Piper PA-28180, N43630, registered to Archer Nevada LLC, and piloted by a private pilot, was
destroyed when it impacted mountainous terrain during cruise flight, 6 miles
northwest of Centennial, Wyoming. Night visual meteorological conditions prevailed.
The personal flight was being conducted under the provisions of Title 14 Code of
Federal Regulations Part 91 on a visual flight rules flight plan. The pilot and his two
passengers were fatally injured. The cross-country flight departed the Rock SpringsSweetwater County Airport (RKS) approximately 2115, and was en route to Grand
Island, Nebraska (GRI).
Controlled Flight Into Terrain
• According to Blue Ridge Aeronautics, a flight school in
Vacaville, California, the flight departed Nut Tree Airport (KVCB)
approximately 1100 Pacific standard time. The flight was to
travel to Grand Island, Nebraska, on the 17th and continue on
to Chicago, Illinois, on the 18th. The pilot reported to the flight
school that he intended to follow Interstate 80 for the entire
flight.
According to the airport manager in RKS, the airplane arrived
approximately 2030 and obtained fuel services. The airplane
did not arrive in GRI and an Alert Notification (ALNOT) was
issued for the missing airplane. According to National Track
Analysis Program (NTAP), the airplane was tracked from RKS
to 10 miles west of Centennial. Search and rescue crews
located the airplane wreckage approximately 0830 on the
morning of January 19th.
Controlled Flight Into Terrain
• The National Transportation Safety Board investigator-in-charge arrived on
scene approximately 1300 on January 19, 2007. The accident site was
located in mountainous, forested, snow covered terrain. A global positioning
system receiver reported the coordinates of the main wreckage as 41
degrees 21 minutes 58.6 seconds north latitude, and 106 degrees 15
minutes 29.6 seconds west longitude. The accident site was at an elevation
of 10,710 feet mean sea level and the airplane impacted on a magnetic
heading of 260 degrees. The wreckage consisted of the fuselage,
empennage, and the left wing. The right wing separated partially and was
found adjacent to the belly of the fuselage. The wreckage came to rest
inverted in approximately 3 to 5 feet of snow.
The closest official weather observation station was Laramie Regional
Airport (KLAR), Laramie, Wyoming, located 27 nautical miles (nm) east of
the accident site. The elevation of the weather observation station was 7,278
feet msl. The routine aviation weather report (METAR) for LAR, issued at
0953, reported, winds, 290 degrees at 9 knots, gusting to 18 knots, visibility,
10 statute miles; sky condition, clear; temperature minus 10 degrees Celsius
(C); dewpoint, minus 18 degrees C; altimeter, 29.94 inches.
Controlled Flight Into Terrain
Further Study
 For Further Study
 http://www.mountainflying.com/
 Books by Sparky Imeson
 “The Mountain Flying Bible”
 “The Shirt Pocket Mountain Flying Guide”
 Order them here: https://secure.airbase1.com/mtnflying/orders.asp
 "Hypoxia, Oxygen and Pulse Oximetry," Furgang, Fred, MD.
 http://www.flightstat.nonin.com/Hypoxia.pdf
 Pulse Oximetry and the Oxyhemoglobin Dissociation Curve
 http://www.continuingeducation.com/nursing/pulseox/pulseox.pdf