Runway gradient: landing and takeoff roll
Runway gradient: slope as a percentage. 2% = 2 ft height change per 100 ft length. Upslope = uphill. Downslope = downhill.
| Slope | Landing roll (TP 1102) | Takeoff roll (PHAK ch.11) |
|---|---|---|
| Upslope | Shorter | Longer |
| Downslope | Longer | Shorter |
- Landing: even an unseen gradient can add real distance (TP 1102).
- Marked downslope: may land uphill and accept a slight tailwind (TP 1102).
Gradient correction: charts give % of book distance. Rate is aircraft-specific POH/AFM data, supplied by the question (e.g. 10% per 1% gradient: 2% gradient = 20%).
| Phase | Slope | Roll becomes | Formula |
|---|---|---|---|
| Landing | Downslope | Longer | corrected = book × (1 + rate × grade%) |
| Landing | Upslope | Shorter | corrected = book × (1 - rate × grade%) |
| Takeoff | Upslope | Longer | corrected = book × (1 + rate × grade%) |
| Takeoff | Downslope | Shorter | corrected = book × (1 - rate × grade%) |
Trap: same slope, opposite landing and takeoff effect. Do not carry takeoff direction into landing.
References
- FAA-H-8083-25 PHAK ch.11, Runway Surface and Gradient
- TP 1102 Aeroplane Flight Training Manual, Approach and Landing: Runway Gradient
- Aircraft POH/AFM (performance section, gradient correction convention)