PA.IV.H.K2FAA-S-ACS-6C · Nov 2023Knowledge
Effects of atmospheric conditions, including wind, on approach and landing performance.
Effects of atmospheric conditions, including wind, on approach and landing performance.
Bottom line
High density altitude is an environmental hazard that affects takeoffs, climbs, and landings. At a high altitude field, the same indicated airspeed as at low elevation fields results in higher true airspeed, a faster landing speed, and a longer landing distance. On final approach, rising air from terrain devoid of vegetation sometimes produces a ballooning effect that can cause a pilot to overshoot the intended landing spot.
Key numbers
| Number | What it means |
|---|---|
| Do not fly a light aircraft when winds aloft, at the proposed altitude, exceed 35 miles per hour | Winds aloft |
| Wind across the range at 15 knots or better at an intersection angle of not less than 30 degrees | Mountain wave |
| At airports with elevations of 2,000 feet and higher, when the temperature reaches a predetermined level | Density advisory |
| Within 100 to 200 feet of the ground, vortices of larger aircraft move laterally at 2 or 3 knots | Vortex drift |
| A light wind with a cross-runway component of 1 to 5 knots can hold the upwind vortex in the touchdown zone | Crosswind vortex |
FAA references
- PHAK ch. 12 (p. 12-8) — FAA-H-8083-25C (2023)
- AIM 7-6-7 (Mountain Flying) — AIM Basic 2/20/25 w/ Change 1 (8/7/25) & Change 2 (1/22/26)
- AIM 7-4-4 (Vortex Behavior) — AIM Basic 2/20/25 w/ Change 1 (8/7/25) & Change 2 (1/22/26)
- AFH ch. 12, Operational Procedures (p. 12-4) — FAA-H-8083-3C
- PHAK ch. 11 (p. 11-16) — FAA-H-8083-25C (2023)
- RMH ch. 3 (p. 3-7) — FAA-H-8083-2A
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