PA.IV.C.K1FAA-S-ACS-6C · Nov 2023Knowledge
Effects of atmospheric conditions, including wind, on takeoff and climb performance.
Effects of atmospheric conditions, including wind, on takeoff and climb performance.
Bottom line
High density altitude means an increase in runway length requirements for takeoff and landings, and a decreased rate of climb. Due to reduced drag in ground effect, the aircraft may seem capable of takeoff well below the recommended speed.
Key numbers
| Number | What it means |
|---|---|
| approximately 2,000 feet at an operational altitude of 5,000 feet for an average small airplane requiring 1,000 feet at sea level under standard atmospheric conditions | Takeoff run |
| 70 percent of lift-off airspeed by the midpoint of the runway, assuming runway length is appropriate for takeoff | Halfway rule |
| do not fly a light aircraft when winds aloft, at the proposed altitude, exceed 35 miles per hour | Winds aloft |
| broadcast at airports with elevations of 2,000 feet and higher when the temperature reaches a predetermined level | DA advisory |
FAA references
- AIM 7-6-7 (Mountain Flying) — AIM Basic 2/20/25 w/ Change 1 (8/7/25) & Change 2 (1/22/26)
- PHAK ch. 5 (p. 5-12) — FAA-H-8083-25C (2023)
- AIM 7-6-8 (Use of Runway Half-way Signs at Unimproved Airports) — AIM Basic 2/20/25 w/ Change 1 (8/7/25) & Change 2 (1/22/26)
- PHAK ch. 5 (p. 5-42) — FAA-H-8083-25C (2023)
- AFH ch. 9 (p. 9-12) — FAA-H-8083-3C
- RMH ch. 3 (p. 3-7) — FAA-H-8083-2A
- RMH ch. 3 (p. 3-6) — FAA-H-8083-2A
- PHAK ch. 11 (p. 11-12) — FAA-H-8083-25C (2023)
Build understanding you can use
Unlock the full lesson and continue studying this element.
- Full teaching sections: What it is; Key points; Rules and numbers; How it is done
- Check your understanding with answers you can reveal
- Common mistakes paired with the FAA facts that correct them