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DO'S AND DON'TS
OF MOUNTAIN FLYING

 

Sitting next to a fireplace with crackling wood on a blustery winter day can result in daydreaming of taking a relaxing trip to the mountains – without even considering those pesky mosquitoes – that becomes reality for many pilots during the summer months.

"Know before you go is sound advice for the novice pilot flying over or through the mountains.

Mountain flying is not a hit-and-miss proposition where you meander through the mountains, navigating valleys and ridges, and then by luck plant the airplane onto a backcountry strip. Rather it is precise flying made safer by using every available clue about the weather and the terrain to accomplish the operation desired.

All flying involves risk. Mountain flying is a calculated risk where exposure to hazards can compromise the safety of flight. The decision-making evaluations concerning mountain flight are appraised for a safe outcome. Mountain flying is not accomplished by rote memory, it is done by thinking about the outcome of various courses of action available to the pilot and weighing the options. This requires an understanding of the conditions of flight, the limitations of the airplane, the limitations of the pilot, and the procedures and techniques to be followed.

You will want to conduct your excursion to those scary old precipice-formed highlands in a safe manner, so, being a conscientious pilot you are going to research the various procedures and the techniques for the operation. You will probably find some mountain flying techniques that may tax a novice pilot. In trying a new technique or procedure, if you find it causes you worry or concern instead of presenting a challenge, don't do it. Fly your experience level, not that of someone writing about how you should be doing it.

EXPERIENCE REQUIREMENTS

You might encounter the admonition, "Don't fly in the mountains until you have a minimum of 250-hours flight time." Some flight schools teaching mountain flying courses will not accept a student for training unless that student has a minimum of 250 hours of flight time. While this may be a realistic guideline, it is difficult to determine that a pilot can operate at a backcountry airstrip based on the number of flight hours he has logged. Without the proper background and training, hours alone do not "prove" the pilot is capable of flying the backcountry. Obviously the more hours a pilot has, the greater his experience level.

I am not convinced that this is a valid value judgment. Some pilots with fewer than 200 hours have impressed me with the operating safety and pilot skills. Other pilots with more than 1,500 hours of flight time have scared the bejeezus out of me.

A more realistic "ruler" to gauge whether or not it is safe for a pilot to operate at a backcountry strip is to demand perfection in three areas:

  1. Knowledge of stalls – what will the airplane do if stalled during a slip or during a skid?

  2. Airspeed control – be able to maintain the approach airspeed within about +/- 3 knots on approach.

  3. Spot method for landing – learn this technique and use it on all landings.

DO'S AND DON'TS

  • DON'T fly into unimproved mountain strips without a minimum of 150 hours of flight experience. Even then, be proficient at slow flight maneuvering, being able to maintain the approach airspeed within 3 knots and know how to perform the spot method for landing.

  • DON'T let a passenger pressure you into initiating the flight if you are uncomfortable about the weather conditions or aircraft performance.

  • DON'T plan a cross-country flight into the mountains when the wind at mountaintop level exceeds 25 knots unless you are experienced in operating in strong updrafts, strong downdrafts and moderate or greater turbulence. This recommendation does not preclude taking a "look-see." Sometimes with a stable air mass the air will contain very little turbulence during these high-wind conditions; at other times mountaintop winds of 15 knots in an unstable air mass may make the flight dangerous. Expect the wind velocity to double or more in mountain passes and over the ridges due to a venturi effect.

  • DON'T choose a route that would prevent a suitable forced-landing area.

  • DON'T leave the airplane without a valid, compelling reason if you execute an emergency or precautionary landing. Temporary evacuation may be necessary if a fire hazard exists.

  • DON'T go if the weather is doubtful or "bad."

  • DON'T become quiescent with weather reports of ceilings of 1,000 to 2,000 feet in the mountains. The ceiling is reported above ground level. Many weather reporting facilities in the mountains are surrounded by mountains that extend thousands of feet higher than the reporting station. Clouds may obscure the mountains and passes in the vicinity.

  • DON'T fly VFR or IFR in the mountains in an unfamiliar airplane make and model. It is required that you learn the flight characteristics, slow flight and stalls in various configuration beforehand.

  • DON'T make the landing approach at too slow an airspeed. Some pilots feel they have to make a low approach on the backside of the power curve to get into a mountain strip. The "handing on the prop" operation is dangerous. Use a stabilized approach for all landings. Airspeed while maneuvering to the airstrip is 1.3 Vso. Begin slowing the airspeed on final approach to cross the threshold at about 1.15 Vso.

  • DON’T make the landing approach too slow. Some pilots feel they have to make a low approach on the backside of the power curve to get into a mountain strip. This “hanging on the prop” is a dangerous operation. Use a stabilized approach for all landings.

  • DON’T operate low-performance aircraft into marginal mountain strips. If in doubt about your takeoff, use the “sufficient runway length” rule of thumb.

  • 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 close to rough terrain or cliffs when the wind approaches 20 knots or more. Dangerous turbulence may be encountered.

  • DON’T fail to realize that air, although invisible, acts like water and it will “flow” along the contour of the mountains and valleys. Visualize where the wind is from and ask yourself, “What would water do in this same situation?”

  • DON’T slow down in a downdraft. By maintaining your speed, you will be under the influence of the downdraft for a lesser period of time and lose less altitude overall.

  • DON’T forget or fail to realize the adverse effect of frost. Less than 1/8 inch of frost may increase the takeoff distance by 50 percent and reduce the cruise speed by 10 percent. Often, if the airplane becomes airborne, the smooth flow of air over the wings is broken up by the frost and the extra drag prevents the airplane from climbing out of ground effect.

  • DON’T give insufficient attention to the importance of fuel and survival equipment. It is important to keep the airplane light, but don’t skimp on these items.

  • 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.

  • DON’T fail 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.

  • DON’T be too proud or too vain to check with experienced mountain pilots concerning operations to and from unfamiliar fields.

  • DON’T attempt VFR flight in mountainous terrain unless you have the minimum visibility you have established as a personal safety standard.

  • DON’T become complacent about the horizon when flying with outside visual reference. A gentle upslope terrain may cause an unknown constant climb with the possibility of an inadvertent stall. The horizon is the base of the mountains some six to eight miles away.

  • DO file a flight plan for each leg of your flight. Also, make regular position reports to allow search-and-rescue personnel to narrow down the search area if you are overdue on the flight plan.

  • DO check all aspects of the weather including weather reports and forecasts.

  • DO familiarize yourself with the high-altitude characteristics and performance of your airplane. This includes the takeoff and landing distance and rate of climb under various density altitude conditions.

DO spend some time studying the charts to determine the lowest terrain along the proposed route of flight. If possible, route the flight along airways.

  • DO have confidence in the magnetic compass. The compass (unless it has leaked fluid or someone has placed interfering metal near its magnets) is the most reliable instrument. Charts will show the areas of local magnetic disturbance that may affect the accuracy of the compass reading.

  • DO plan the fuel load to allow flight from the departure to the destination airport with a reserve to counter unexpected winds.

  • DO fly a downdraft, that is, maintain speed by lowering the nose of the airplane. Unless the airplane is over a tall stand of trees or near a shear cliff, the downdraft will not extend to the ground (exception: microburst).

  • DO use Sectional Aeronautical Charts instead of World Aeronautical Charts (WAC) because of the greater detail (8 miles per inch).

  • DO approach ridges at an angle. The recommendation is to use a 45-degree angle approach when in a position of one-half to one-quarter mile away. This allows an escape, with less stress on the pilot and airplane, if unexpected downdrafts or turbulence are encountered. Flying perpendicular to the ridge, rather than at a 45-degree angle, does not mean you cannot escape the downdraft or turbulence by making a 180-degree turn. But, it does mean the airplane will be subjected to the effects of the downdraft and turbulence for a greater period of time. Usually, a steeper bank will be required to make the 180-degree turn. This will increase the g-loading stress on the airplane.

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  • DO use horse sense (common sense) when performing takeoffs or landings at mountain strips. If you have any doubt about the operation, confirm the aircraft performance using the Pilot’s Operating Handbook or Owner’s Manual. If the physical conditions are adverse and compromise the operation, delay the operation until conditions are better.

DO count on the valley breeze (wind blowing upstream during the morning hours) and the mountain breeze (wind blowing downstream during the evening hours). In an otherwise calm wind condition the valley breeze will create an approximate 4-knot tailwind for landing upstream. The mountain breeze will cause an approximate 8-knot to 12-knot tailwind for takeoff downstream.

DO make a stabilized approach for landings. Since the late ‘60s the power-off approach has been discouraged because of thermal shock to the engine.

DO remember your study of aerodynamics. It is possible to stall the airplane at any airspeed and any attitude (providing you are strong enough and the airplane doesn’t break first). If a stall is entered in the same manner, for example, with a slow deterioration of the airspeed, it will stall at the same indicated airspeed at all altitudes even though the true airspeed is greater at higher altitudes.

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