Operations During A Cross-country Flight
Starting, Taxi, and Run-up
Starting and taxi at high altitudes are performed as you would at sea level, except you must lean the mixture significantly to avoid fouling the spark plugs. Run-up is also normal except a full power run-up of non-turbocharged engines should be used to set mixture for takeoff power. The POH should be followed strictly for turbocharged engine operation.
For takeoff, the minimum flap setting recommended by the POH is usually recommended for best performance. A full power check should be performed on the runway, adjusting mixture for best power if necessary, and checking for proper engine RPM, manifold pressure, and fuel flow. As discussed earlier, rotation and liftoff should be at normal indicated airspeeds. It is important not to over rotate to avoid high drag and poor takeoff performance.
A normal climb profile is usually sufficient for most mountain airports you will visit. Your POH should be the guide for selecting the proper speeds for the conditions. For most light aircraft, the initial climb will be at the best rate of climb IAS until reaching at least 1,000 feet. If the winds at mountain top level are above 20 knots, increase that to 2,000 feet. Plan to be at that altitude at least three miles before reaching the ridge and stay at that altitude until at least three miles past it. This clearance zone will give you a reasonable safety zone to avoid the most severe turbulence and down drafts in windy conditions.
If conditions or airplane performance dictate, you may need to fly along the windward side of a ridge to find updrafts for gaining altitude before crossing a ridge. You may also need to circle before reaching the ridge if climbing out of a valley airport.
When you actually cross a ridge, you should do so at a 45 degree angle to the ridge. This allows you to turn away from the ridge quicker if you encounter a severe downdraft or turbulence. Once you have crossed the ridge, turn directly away from it at a 90 degree angle to get away from the most likely area of turbulence quickly. Plan your crossing to give yourself the ability to turn toward lower terrain quickly if necessary.
As you fly your mountain trip, continually visualize what the weather and winds are doing so you can take best advantage of them. For example, if flying in a valley, it is usually best to fly on the side of the valley that will have the updrafts, the side the wind is blowing toward. Turbulence due to the rough terrain may make the flight uncomfortable, but may also require that you fly at maneuvering speed. Remember that maneuvering speed decreases as the airplane's weight decreases. You should know what your maneuvering speed is for the weight at which you are flying and be able to go to it quickly if you encounter rough air.
Pilotage and dead reckoning will be your primary type of navigation. VORs are usable in limited areas, but suffer from limited range and other problems. LORAN and GPS systems work quite will, however, and can be used effectively to maintain your positional awareness.
When you first arrive over a mountain airport, take a good look around before you descend to it and plan your departure track. Look for escape routes and emergency landing sites in the event of an engine failure right after takeoff. Also, study the terrain you will have to climb over as you depart.
Plan your approach path as you start your descent. Some mountain sirports are confined in valleys that make a normal approach difficult. Study your options before committing to a lower altitude.
Approach and Landing
Approach and landing should be normal at most mountain airports. Plan to lfy a stabilized approach to the desired touch down spot. Since mountain winds are sometimes tricky, be aware of windshear and go around if necessary.