VFR · Lesson 27 · 7 min · ACS PA.I.F
Reading Performance Charts and Load Factor
Summary
Read charts by interpolating with a safety margin. Load factor grows with bank — 2.0 Gs at 60 degrees — and raises stall speed by the square root of the load factor.
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Reading performance charts · Topic mastery: Not started
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When a performance chart value falls between two printed lines, what should the pilot do?
Why this matters in flight
The numbers you need for a safe flight already live in the performance charts. Reading them correctly and understanding how a steep turn multiplies the load on the wing turns published data into good decisions.
A performance chart turns conditions into predicted numbers. To use a takeoff or landing chart you enter with pressure altitude and temperature, then track across for weight, wind, and obstacle height, interpolating between the printed lines rather than rounding to the nearest one. The chart assumes a well-maintained airplane flown at the book technique and speeds, so real-world results can be worse and a safety margin is wise. Load factor is a related idea in the air. It is the ratio of the load the wings carry to the airplane weight, measured in Gs. In a level turn it grows with bank angle — roughly 1.15 Gs at 30 degrees, 1.41 Gs at 45 degrees, and 2.0 Gs at 60 degrees. Because stall speed increases with the square root of load factor, that 60-degree turn raises the stall speed by about 40 percent, which is why an accelerated stall can surprise a pilot in a steep turn.
Key terms
- Interpolation
- Estimating a value between two printed chart values.
- Load factor
- Wing load divided by aircraft weight, expressed in Gs.
- Accelerated stall
- A stall at higher-than-normal speed caused by increased load factor.
Sources & references · 2 · 2 linked
Every claim traces to a source — paraphrased knowledge elements pointing at the governing FAA publication. Items marked verified have been checked against the retrieved source text; the rest are pending verification. Where the exact page or regulation has been located in a retrieved document, the source links straight to it.
- FAA-H-8083-25 (performance charts) — Pilot’s Handbook of Aeronautical Knowledge verifiedPilot’s Handbook (document)
- FAA-H-8083-3 (turns/load factor) — Airplane Flying Handbook verifiedFAA-H-8083-3C (p. 211)
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