Hot or high, density altitude should be on your mind
Airplane engines and lift surfaces (propeller, wings) only know of one altitude—density altitude. Density altitude is the pressure altitude corrected for nonstandard temperature.
What does that mean for you? If the day is hot, the airport is high, or both, most airplanes will suffer a decrease in performance. That’s because pressure altitude decreases with (absolute) altitude, and warm air is less dense than cool air.
To calculate density altitude, set the altimeter to 29.92, read what it says on the altimeter, take the temperature and plug the numbers into your flight computer. Then use that altitude to compute the aircraft’s performance specifications. You might be surprised how much density altitude affects performance.
AOPA Flight Training staff
AOPA Flight Training Staff editors are experienced pilots and flight instructors dedicated to supporting student pilots, pilots, and flight instructors in lifelong learning.
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