Don’t Let Mountain Flying Become a Perfect Storm

AINsafety » July 16, 2012
Courtesy Terri Quinlan ©2012 www.terriquinlan.com
July 12, 2012, 4:40 PM

Flatlanders—anyone who flies east of the Rockies, even those flying sophisticated single-engine turboprops and light jets—can easily find themselves in trouble when flying in regions where IFR Minimum Enroute Altitudes (MEAs) in the 14,000 foot-plus range are common. And there’s shooting an instrument approach to a mountain airport to contend with. John Mahany, a Master CFI and facilitator at numerous mountain-flying seminars, offers this advice on how to stay “grounded” in reality when flying near cumulo-granite.

“If you’ve never flown into a particular mountain airport, such as Rifle (RIL, elevation 5,537 feet), I tell students to watch the weather there for at least a week before their flight. Mountains create weather and it changes much more quickly than in the plains region.” He also recommends contacting operators at potential destination airports and talking with local experts who understand the local weather patterns and know the terrain.

Mahany also cautions pilots to learn about mountain waves, when strong winds flow perpendicular to the mountains and set up extremely turbulent conditions as far as 200 nm downwind of the peaks. “Those big lenticular clouds are clues that the mountain peaks are poking up into the jetstream and high winds and mountain wave conditions are present,” he said. He also suggested pilots add extra altitude when flying on the downwind side of the mountains to cope with wave-induced down drafts.

The effects of a near-five-figure density altitude are another concern. “Even in a King Air, pilots won’t operate out of Aspen, Rifle or Eagle in the middle of a summer day. They go earlier, when the aircraft performs better,” Mahany said. Pilots also need to remember that there are few IFR alternate airports in mountainous areas.

Failure to correctly calculate takeoff weight from mountain airports can spell disaster. The pilot operating handbook will tell you whether the aircraft will fly after an engine failure, but it takes additional math to determine whether the aircraft will clear obstructions on one engine.

Finally, “Never arrive at a mountain destination for the first time at night,” Mahany said. “The sun appears to set faster in the mountains and it gets dark quickly.”

Tags: Wind

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Michael Mahany
on July 24, 2013 - 4:15pm

I'm a non-pilot, but fascinated by mountains and all things related.
Sounds like mountains command understanding and respect. I guess the
old saying "Everybody complains about the weather, but nobody
ever does anything about it!" is NOT true of pilots, who are clearly 'dialed in' on the topic. I enjoyed the piece.

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