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IR.I.B.K3cFAA-S-ACS-8C · Nov 2023Knowledge

c. Temperature and heat exchange

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: c. Temperature and heat exchange

Bottom line

ISA values can be calculated for various altitudes using a standard lapse rate of approximately 2 °C per 1,000 feet. Density Altitude–The combination of high temperature and high elevation affects aircraft performance.

Key numbers

Key numbers for c. Temperature and heat exchange
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 (p. G-9) — FAA-H-8083-3C
  2. RMH ch. 3 (p. 3-7) — FAA-H-8083-2A
  3. AFH ch. 11 (p. 11-7) — FAA-H-8083-3C
  4. AFH ch. 12, Heat Management (p. 12-11) — FAA-H-8083-3C
  5. AC 91-92 Appendix A — AC No: 91-92
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