Mountain flying presents its own unique sets of challenges and rewards. By training appropriately, reviewing the differences, and preparing well, you can ensure your mountain flight is a safe and enjoyable one.
If you’ve only ever flown in low-altitude, flat regions, you may be unprepared for the differences and dangers of flying in the mountains. It’s easy to make a list of the possible risk factors involved in mountain flying and claim that most of those same risks exist at lower altitudes, but there’s a stark difference. You may sometimes encounter one, maybe two of those hazards over flat land. You’re likely to run into most of them in the course of one mountain flight.
That is not to say that flying in the mountains is too dangerous. Experienced mountain pilots know well the bountiful opportunities opened up to them by flying in such areas. But ample preparation is needed before attempting such a flight for the first time, and old hands would do well to frequently review mountain flying differences and cautions so as not to grow complacent.
Should you fly?
It’s not enough to simply review the differences and take off. While the FAA does not require or certify mountain flying courses, it is highly recommended that you take at least one before beginning mountain flying. You’ll want to draw upon the experience of a seasoned mountain pilot your first time out. Wait to tackle such an endeavor until you are practiced in stall recovery, airspeed control, and maneuvering in moderate to high turbulence.
Once you have taken a course, you’ll want to carefully plan your mountain flight. Unless you are very experienced, steer clear of flying at night, in instrument meteorological conditions, or with winds over 25 knots. Even for experienced pilots, such conditions are unfavorable due to the unpredictability of winds, changing weather, and visibility troubles in the mountains. Winds aloft above 30 knots are almost always a no-go in the mountains for anyone.
One of the primary factors affecting mountain flight is the high density altitude. High, hot, and humid are par for the course in mountain regions, especially on summer afternoons. This results in thinner air and poor aircraft performance. An aircraft, particularly a fixed wing aircraft, that performs poorly at sea level will prove a hazard in the mountains, and well-performing aircraft at sea level may still struggle at high density altitudes.
A high density altitude equates to a longer takeoff run, a longer landing run, and a much lower rate of climb. Carefully check your calculations for how much runway you’ll need to take off, and don’t be fooled when your aircraft doesn’t start to lift from the runway at the moment it normally does at sea level. You need more speed than you might think to take off in the mountains, and you may need a better rate of climb to clear obstacles than you might expect. Trust your math, your instruments, and what’s actually happening around you rather than what you expect to happen.
Finally, be aware that a full rich mixture for takeoff may not be ideal depending on the type of aircraft you are flying. Non-turbocharged aircraft may need to run the engine up to full power, leaning the mixture until maximum RPM, then enrichen. This does not apply to turbocharged aircraft. Check your POH for more details on how high altitude conditions may change take-off procedures.
En-route and landing
Once airborne, there are several hazards to watch out for when flying in the mountains. The most obvious concerns are the wind and weather. Turbulence, wind shear, and microbrusts are common due to wind patterns over the mountains. Be on the look-out for the signs of mountain wave turbulence: rotor clouds, cap clouds, and standing lenticular clouds. Avoid areas with these clouds, and be especially wary of flying over mountaintops with a tailwind, as the wind will often be swift and turbulent on a downward slope.
Similarly, when approaching a ridge or a pass to fly over it, approach at a 45 degree angle. That way, if there is a significant wind coming over the top of the ridge and you must turn away, you have a better chance of being able to do so. When you reach the top of the ridge, turn perpendicular to it as you depart.
Since you’ll be at a high altitude, depending on what you’re flying, you may need supplemental oxygen to avoid hypoxia. Be aware of the signs of imminent hypoxia, such as a sense of euphoria. Night flying is especially dangerous at high altitudes because of hypoxia, since a loss of night vision is its earliest symptom.
To avoid hypoxia, heavy turbulence, and other factors, you may prefer to fly in valleys where possible. While this can ease your flight, never fly down the center of a valley. Fly down one side, ideally the updraft side, to give yourself room to turn around if needed. Never fly through a narrow canyon or valley that does not offer enough room to execute a 180 degree turn, if necessary.
Finally, consider the following when landing: recall that the high density altitude will increase your landing run. Landing uphill can make things a touch easier, but it also creates an illusion of being too high on the approach, so be forewarned. Review the approaches at your destination airport beforehand. Mountain airports often have strange approaches due to deceptive terrain, slopes, or odd geography that must be worked around.
Some Final Tips:
- Watch your ceilings. Since airports are often in valleys, the ceilings they provide will end up being much closer to where you’re actually going to be flying than normal.
- If you must fly at night, try to find a lit reference point, such as a highway, to follow.
- Ask locals for advice. Local pilots can often tell you more about conditions in remote areas than the sparse weather reports.
- Review the types, locations, and rules for Special Use airspace, especially if your flight is in the southwest United States.
Above all, if any factor makes you feel uncomfortable or uncertain, don’t fly. Mountain flying can be a rewarding experience for those who undertake it with respect for the conditions and differences. Plan ahead, and enjoy your flight.
- Wind Shear
- Physiology and First Aid
- High Altitude Weather and Aerodynamics