following is a summation of the minimum knowledge areas needed to fly
safely in the mountains. Further study and instruction (from a
knowledgeable instructor) are required prior to flying the mountains. This
minimum knowledge information is intended to supplement, not replace, your
preparation for flying in the mountains.
Without exception, you must adhere to the two
basic premises of mountain flying, whether flying "with the mountains" or
over the mountains.
The novice mountain pilot should plan to fly
2,000 feet above the terrain along the route of flight. When approaching
within ½ to ¼ mile from the mountain ridges, turn to approach the ridge at
a 45-degree angle. This permits an easy escape with less stress on the
airplane if downdrafts or turbulence are encountered. Never fly in a
canyon where there is not room to turn
- Never fly beyond the point of no
When flying upslope terrain, the "point of no
return" is defined as the position where, if you reduce the throttle to
idle, you can lower the nose for a normal glide and perform a 180-degree
turn without impacting the ground. At or prior to this point, circle away
from the mountain to gain additional altitude before
A complete check of the weather
is necessary to develop a go/no-go decision. Stay out of marginal weather
areas. Winds aloft greater than 30 knots at cruise altitude usually means
the novice pilot should delay or postpone the flight until more favourable
at Telluride, Colorado, perched 1,000 feet above the San Miguel
River on Deep Creek Mesa (about 4 ½ miles west of town. It is the
highest altitude commercial airport in the U.S. Sinking air is a
problem when surface winds reach 15 knots or
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.
A handy rule-of-thumb for operating from
a short runway is that if you obtain 71 percent of the speed
necessary for rotation at the halfway point of the runway, you can
take off in the remaining distance.
Note: This rule of thumb guarantees
takeoff performance, but not rate-of-climb after the
For density altitudes of 3,000 feet or
greater, lean the mixture for takeoff according to the airplane
manufacturer's recommendation. Do not lean turbocharged or
supercharged engines for takeoff.
Lacking any recommendation, lean the
mixture during the takeoff roll slowly until encountering engine
roughness, then enrich for engine smoothness.
Turn to approach ridges at a 45-degree
angle to provide you the option of escaping toward lowering terrain.
Begin this turn to approach the ridge at the 45-degree angle when
you are about 1/2 to 1/4 mile from the ridge.
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.
As you near the ridge, 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.
Until you have the experience of flying
canyons with a knowledgeable instructor, do not fly up canyons. If
it is necessary to fly in a canyon, gain altitude, fly to the head
of the canyon, then fly downslope terrain.
Landing at a short mountain strip
requires exact airspeed control to eliminate float. A
10-percent increase in the proper approach speed results in a
21-percent increase in landing distance.
Use the same indicated airspeed for
approach when landing at a high-elevation mountain strip that you
would use for the approach at a sea level airport. The thin air at
high altitudes affects the airspeed indicator.
A rule-of-thumb states that the airplane
flies faster than indicated airspeed at altitudes above sea level by
approximately 2-percent-per-thousand feet above sea level. This is a
built-in compensator for reduced lift caused by the thin air at
higher altitude airports.
Allow a minimum of an extra half hour of
daylight if your destination is a mountain strip without runway lighting.
There may be plenty of daylight at cruise altitude, but darkness may exist
because of shadows at the valley
Landing at Possum
Creek airstrip, 10,010-foot elevation.
The takeoff distance varies with the gross
weight. A 10-percent increase in the takeoff gross weight (while not
exceeding the maximum allowable gross weight) will cause a:
5-percent increase in the speed necessary for
9-percent decrease in acceleration to takeoff speed,
21-percent increase in the takeoff
The first consideration for takeoff from a
strip surrounded by mountains is terrain clearance. A considerable amount
of time may be required to circle, climbing to the en route altitude prior
to turning on course.
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?"
You can then picture areas of downdrafts,
updrafts and splashes of turbulence.
If you encounter unexpected downdrafts,
diving–away from the visualized downdraft–to maintain airspeed will
generally lessen the total displacement effect of the downdraft (altitude
loss). Although the rate of descent is greater at the higher airspeed, you
will be under the influence of the sink for a shorter period of
Everyone flying in the mountains will encounter
situations when it becomes necessary to make a 180-degree turn. Forget
hammerhead turns, wingovers, chandelles and the other fancy manoeuvres. By
the time you figure out you are in trouble and need to turn around, there
is insufficient speed to perform these manoeuvres.
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.
The mountainous terrain surrounding many air
strips prevents a normal descent from cruise altitude to pattern altitude.
It is necessary to make progressive power reductions to prevent thermal
stresses from being induced in the engine. This allows the engine to cool
slowly, preventing not only thermal shock, but also preventing de-tuning.
Always make smooth power changes when adding or reducing power.
caution: This is
not the total information you need to fly safely in the mountains. It is
merely an outline of the minimum information that should be