AA.I.D.K4FAA-S-ACS-11A · Nov 2023Knowledge
Load factor at high altitude and its effect on high and low speed operating margins.
Load factor at high altitude and its effect on high and low speed operating margins.
Bottom line
The margin over low-speed stall buffet decreases, as well as the margin below Mach buffet, because of the increased velocity of the air over the wing resulting from the higher AOA.
Key numbers
| Number | What it means |
|---|---|
| 135 kts at FL 350 (typical jet, 1.0 G buffet-free margin) | 1.0 G margin |
| 26 kts at FL 450 (typical jet, 1.0 G buffet-free margin) | 1.0 G margin |
| Mach buffet slightly above MMO 0.82 Mach; low-speed buffet at 0.60 Mach at 51,000 ft MSL, 1.0 G | Buffet speeds |
FAA references
- AC 61-107, para. 3-2, 3-3 — AC No: 61-107B
- AFH ch. 16 (p. 16-6) — FAA-H-8083-3C
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