mountain flying

NOTICE: The 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.

basic premises

Without exception, you must adhere to the two basic premises of mountain flying, whether flying "with the mountains" or over the mountains.

Always remain in a position where you can turn toward lowering terrain

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 around.

Never fly beyond the point of no return.

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 proceeding.

mountain meteorology

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 conditions prevail.

Airport (TEX) 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 more.

density altitude

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.

runway length

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 takeoff.

Short-field takeoff

leaning the mixture

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.

approach ridges

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.

flying canyons

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.

airspeed control

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 destination.

Landing at Possum Creek airstrip, 10,010-foot elevation.

gross weight

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 takeoff;

  • 9-percent decrease in acceleration to takeoff speed, and

  • 21-percent increase in the takeoff distance.

climb out

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 time.

course reversal

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 studied.