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a density altitude of, say, 10,000 feet, you have lost nearly a third of your engine’s total power from that avail- able at sea level.
From a practical point of view, the Cessna 180K I am now fly- ing, which has the 300-horsepower Air Plains Continental 550 modifica- tion, would only put out 69% of its rated maximum power (207 horsepower) in that circumstance. Takeoff distances and climb rates are proportionate to the power available, meaning that in the above situation, the runway re- quirement would increase by at least 30%. The climb rate would be down in the 400-500 fpm range, often insuf- ficient to clear surrounding terrain in the backcountry, even in a modified aircraft like my 180K.
But it is not only the engine that suffers from high density altitude. The wing is less efficient at higher density altitudes than down low. The aircraft must move forward at a higher horizontal speed to lift the same load as at a lower altitude. The combina- tion of lower power output and higher true airspeeds required for takeoff is hazardous, especially when taking off from an unimproved surface, which creates additional rolling drag. Simi- larly, on landing, the airplane’s ground speed will be much higher (even with the same IAS), requiring a much lon- ger landing distance. Unfortunately, backcountry airports almost always have very short runways.
The solution to most of this (even if you prefer to avoid getting up early in the morning) is to plan your opera- tions for the early hours of the day and keep the airplane’s total weight as low as possible. If, for example, we depart or arrive at Flying B at 0700 with only two on board and the tanks half full, with a temperature of 50 degrees, the density altitude would be only 3,998 feet, and the adverse effect on both landing and takeoff performance would be much less.
Another problem to consider when operating these single-engine piston airplanes vs. the turbines I had been flying is you only know what the air- craft can do if you try it out yourself. Even in older jets like the Lear 35, we
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