do's and don'ts of mountain flying

DONíT fly into unimproved mountain strips without a minimum of 150-hours total flight experience. Even then, be proficient at slow flight manoeuvring and the spot method for landing.

DONíT plan a cross-country flight into the mountains when the wind at mountaintop level exceeds 30 knots unless you are experienced in this type operation (strong updrafts, strong downdrafts and moderate or greater turbulence). This does not preclude taking a ďlook-see.Ē Often with a stable air mass the air will contain very little turbulence during these high-wind conditions. Expect the wind velocity to double or more in mountain passes and over the ridges due to a venturi effect.

DONíT choose a route that would prevent a suitable forced-landing area.

DONíT 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.

DONíT go if the weather is doubtful or ďbad.Ē

DONíT become quiescent with weather reports of ceilings of 1,000-2,000 feet. The ceiling is reported above ground level. Often, in the mountains, the weather reporting facility will be surrounded by mountains that extend thousands of feet higher than the facility. Clouds may obscure the mountains and passes in the vicinity.

DONíT 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 configurations, beforehand.

DONíT 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 ďhanging on the propĒ is a dangerous operation. Use a stabilized approach for all landings.

DONíT operate low-performance aircraft into marginal mountain strips. If in doubt about your takeoff, use the ďsufficient runway lengthĒ rule of thumb.

DONíT 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.

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

DONíT fail to realize that air, although invisible, acts like water and it will ďflowĒ along the contour of the mountains and valleys. Visualize where the wind is from and ask yourself, ďWhat would water do in this same situation?Ē

DONíT 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.

DONíT 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.

DONíT give insufficient attention to the importance of fuel and survival equipment. It is important to keep the airplane light, but donít skimp on these items.

DONíT fly the middle of a canyon. This places you in a poor position to make a turnaround and it subjects you to shear turbulence.

DONíT 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.

DONíT be too proud or too vain to check with experienced mountain pilots concerning operations to and from unfamiliar fields.

DONíT attempt VFR flight in mountainous terrain unless you have the minimum visibility you have established as a personal safety standard.

DONíT 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 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.

DO use common sense when performing takeoffs or landings at mountain strips. If you have any doubt about the operation, confirm the aircraft performance using the Pilotís Operating Handbook or Ownerís 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 Ď60s 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 doesnít 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.