In any kind of flying operation it is paramount to understand that density altitude is an indicator of aircraft performance. Pilot's Operating Handbook performance data are generally based on standard atmospheric conditions at sea level (15C degree and 29.92 inches of mercury). Aircraft will not perform as published in the POH unless the conditions are the same as published in those Manuals.

Three important factors that contribute to high density altitude:

  1. Altitude - the higher the altitude, the less dense the air

  2. Temperature - the warmer the air, the less dense it is

  3. Humidity - in case of high humidity conditions, it is wise to add 10% to your computed takeoff distance and anticipate a reduced climb rate

The penalties in aircraft performance as a result of high density altitude:

  • increased takeoff distance

  • reduced rate of climb

  • increased TAS (same IAS) on approach and landing

  • increased landing roll distance

High density altitude has particular implications for takeoff/climb performance and lending distance. Pilots must determine the actual density altitude during preflight preparation. If POH is not available, use the Koch Chart to calculate the approximate adjustments for aircraft takeoff distance and rate of climb.

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