July 2008 Issue

Flying in High-Density Altitude Conditions

Use these tips to reliably go beyond the book and ensure adequate performance in high-density-altitude operations.

It happens every summer. Temperatures rise and with them so does density altitude. It may seem we should simply avoid flying when the density altitude (DA) creeps up, but this would be very short-sighted—although there are some hazards warranting a delay when the air heats up (thunderstorms and desert turbulence among them), the fact is we can safely fly in most high-density-altitude conditions. Doing it, however, requires some technique and some compromise. We all learned the basics of density altitude when we first learned to fly. But what are the practical techniques necessary to maximize airplane—and pilot—performance when hot and high? And when do we need to employ them? What is high density altitude? It’s really a function of the airplane’s capabilities...and those of the pilot. You’ll find Piper Cubs and Cessna 150s flying out of Leadville, Colo., (elevation 9927 feet msl), yet hear of DA-related accidents involving much more powerful airplanes at much lower altitudes. Air density increases to "high" levels in summer’s heat, even at relatively low-altitude airports. When you consider that maximum available power drops by about 10 percent for every 3000 feet of density altitude increase above sea level (in naturally aspirated engines), even flat-land flyers need to compensate for power lost due to high DA in summer.

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