Flying Carpet: Mountain Airport

Our friends Steve and Molly recently invited us for a hiking weekend in southwest Colorado. This would be our first summertime visit to 9,070-foot-elevation Telluride Regional Airport (TEX).

Telluride is surrounded on three sides by 12,000- to 14,000-foot mountains, but we could approach from the west at 11,000 feet. Like most Telluride traffic I planned to land on Runway 9 and depart Runway 27 to avoid maneuvering in the dead-end canyon east of the airport. That required good visual flight conditions, and light winds to preclude downwind takeoffs or landings and dangerous downdrafts tumbling over the surrounding mountains.

Given suitable weather, my main concern flying our nonturbocharged Cessna 182 was safely departing such a high-elevation airport in summertime. Temperatures of 48 degrees Fahrenheit to 75 degrees F sound pleasantly cool, but at 10,000 to 12,000 feet density altitude we’d be lucky to get 65 percent of sea-level power at full throttle, and 300 fpm climb.

My performance charts indicated the 7,000-foot runway was plenty for takeoff, but at those density altitudes our normally peppy Skylane might require 10 miles to clear a 1,000-foot ridge. Had we needed to top terrain after takeoff I would have canceled the trip. To the west, however, the ground plunges into the San Miguel River Canyon, meaning we could even descend after takeoff if necessary.

To optimize Telluride departure performance, we needed to take off cool and light. Jean and I packed minimally, and rather than top tanks before leaving Flagstaff, I loaded only precalculated roundtrip fuel plus reserves. That staged us 475 pounds under gross weight to depart Telluride.

We launched on the two-hour flight Friday morning, and sure enough, Telluride’s density altitude was 11,400 feet when we landed. Whether at sea level or 10,000 feet, pilots should always fly the same indicated airspeeds for airport operations. True airspeed, however, increases by about 2 percent per thousand feet of altitude, meaning at Telluride you’re covering ground nearly 20 percent faster than at sea level for the same indicated airspeed. Pilots must resist temptation to slow dangerously below normal approach speed because “this doesn’t feel right.” The airplane will also touch down faster than usual, use more runway, and require a greater turning radius aloft—more reason to avoid circling in Telluride’s cozy canyon.

Following two idyllic days trekking with our friends among wildflowers and waterfalls, we departed cool and early Sunday morning at 10,200 feet density altitude. I leaned the engine in a full-power runup, accelerated in ground effect to best-rate-of-climb speed, and committed to flying by the numbers regardless of poor climb performance out the windshield. We easily cleared the runway and climbed sluggishly homeward. Anyone who thinks piloting is dull should land at a high mountain airport.