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Module 8: Basic Aerodynamics22 Sep 2026

confused about density altitude on a hot day

Exam question

On a very hot day with ambient temperature higher than ISA, your pressure altitude is 20,000 ft. How much will the density altitude be?

  • A.greater than 20000ftCorrect
  • B.less than 20000ft
  • C.the same
Explanation

Density Altitude is pressure altitude corrected for temperature and humidity. Assuming constant humidity ISA or above temperature will further thin the air for a given pressure altitude thus making the density altitude higher.

Priya

asked · 22 Sep 2026

Author
so pressure altitude is 20000ft but its way hotter than isa that day, and apparently density altitude is now HIGHER than the pressure altitude. i thought hot air being less dense would mean the aircraft performs like its at a lower altitude not higher?? or is it the opposite because the engine and wings only care about how thin the air actually is, not what the altimeter says. getting mixed up between what the instrument reads vs what the aircraft actually feels

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