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IR.I.B.K3aFAA-S-ACS-8C · Nov 2023Knowledge

a. Atmospheric composition and stability

ACS element text (the applicant demonstrates understanding of)

Meteorology applicable to the departure, en route, alternate, and destination for flights conducted under Instrument Flight Rules (IFR) to include expected climate and hazardous conditions such as: a. Atmospheric composition and stability

Bottom line

The International Standard Atmosphere (ISA) is a model of standard atmospheric conditions at sea level.

Key numbers

Key numbers for a. Atmospheric composition and stability
NumberWhat it means
59 °F (15 °C) at sea levelISA temp
29.92 "Hg (1013.2 mb) at sea levelISA pressure
approximately 2 °C per 1,000 feetLapse rate

FAA references

  1. AFH Glossary (pp. G-8–G-9) — FAA-H-8083-3C
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