For example, when flying over high terrain, personal minimums for visibility and cloud ceilings should be higher. Emergency landing sites are fewer and should be determined in advance. Density altitude will affect aircraft performance, and your flight path should ensure that you maintain a safe distance away from those beautiful mountains. But one of the most challenging factors to take into account during flight planning and when en route is the wind.

Wind flows up the windward side of mountains. While updrafts can help an aircraft gain altitude, pilots should never rely on them to provide the climb performance needed to clear terrain. Conversely, downdrafts tend to form on the leeward—or back—side of the mountain. Rugged rising terrain also disrupts the smooth flow of wind, creating turbulence and downdrafts that can be intense. The descending winds can pull an aircraft toward the terrain, potentially faster than your aircraft can climb—a very hazardous position. It's important to mitigate this risk by keeping plenty of space between your airplane and the terrain. AOPA Air Safety Institute Vice President of Operations Paul Deres advises, "When crossing ridgelines, approach at an angle that allows you to turn toward lower terrain if necessary. Establish adequate terrain clearance well before reaching the ridge, rather than attempting to outclimb rising terrain."

Lenticular clouds (shaped like a lentil—round and flat with curved sides) form over peaks and ridgelines when winds are strong. This type of cloud is an indication of updrafts, downdrafts, and turbulence that may extend far downwind from where the clouds appear. It's a sign of potentially hazardous conditions, and the presence of a lenticular cloud should be taken as a warning, particularly of turbulence below the clouds.

At mountain airports, terrain can disrupt airflow and cause gusty conditions. When landing at, or departing from, these airports, be alert for winds that are variable in direction as well as speed.

An invaluable flight planning tool is the turbulence forecast found on the Aviation Weather Center website. It is especially helpful because it takes terrain into account, but it may not capture localized conditions around ridges and valleys. It’s important to supplement your knowledge by talking to local pilots familiar with the area, who can offer you tips from firsthand experience. And tools such as terrain information found on avionics and electronic flight bags are helpful for en route planning.

"Perhaps the most important mountain flying skill is knowing when not to fly. Strong winds, turbulence, and downdrafts can overwhelm even capable aircraft, and no amount of mountain scenery is worth pushing beyond your limits," Deres said.

There are numerous mountain flying resources online, including this brochure from the FAA. Also check out the Air Safety Institute's Mountain Flying Safety Spotlight.