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ASI Safety Alert 2021-1

High Density Altitude in the West

A record heat wave is expected to affect several western states beginning June 26, with forecast temperatures 20 degrees above normal in many areas. High temperatures are expected to persist for several days, through the Fourth of July weekend.

Density altitudes and thermal turbulence will be significant factors for pilots flying in these areas. Some backcountry airfields in the region should be considered inaccessible for most aircraft types. Pilots at all airfields in these regions will notice a substantial degradation in aircraft performance.

What you should do:

  • Do not fly in the region before first confirming high density altitude performance for your aircraft.
  • Fly only in the early mornings, preferably before 10:00 am. Carefully monitor outside air temperature.
  • Be aware of the combined effects of thermal and wind turbulence exacerbated by the mountains that can make flying uncomfortable and aircraft control more demanding.

To learn more, watch the AOPA Air Safety Institute’s The Triple H Effect video and visit us online at