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SESK: Stuff Everyone Should Know · sesk.info/pilot-humidity-density-altitude

How does high humidity affect density altitude and airplane performance?

It raises density altitude and reduces performance.

  1. Raises density altitude and reduces performance ✔
  2. Lowers density altitude and improves performance
  3. Has no effect on density altitude

Why: Water vapor is lighter than dry air, so humid air is less dense. Less dense air means a higher density altitude. The engine, propeller and wings all perform worse.

Huh, didn't know that: Density altitude is pressure altitude corrected for nonstandard temperature.

The dad joke
Why do pilots love crisp winter mornings? The air finally shows up for work.
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Sources

  1. FAA Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 4 https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/faa-h-8083-25c.pdf

Test yourself in the game

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