Bouncing & porpoising on landing
Bouncing: sharp touchdown from wrong attitude or too much sink makes angle of attack jump, adds sudden lift. Aircraft does not spring like a rubber ball (AFH ch.9).
- Nearly always paired with excessive back-elevator pressure, applied late to fix attitude.
Porpoising: badly recovered bounce. Aircraft lands nose first, repeats jumps and dives (AFH ch.9).
Porpoise causes:
- Inattention
- Not knowing where the ground is
- Mis-trim
- Forcing aircraft onto runway while it still wants to fly, typically after floating from a fast approach; gust or bump sends it aloft again
- Ground effect weakens elevator: too little nose-up trim can give nose-low contact
Pilot-induced oscillation: untimely control and power inputs raise severity of each contact. Can collapse nose gear.
Recovery (bounce or porpoise):
| Situation | Action |
|---|---|
| Very slight bounce or porpoise | Add power to cushion next touchdown; adjust pitch smoothly |
| Crosswind | Keep correction, upwind wing lower; releasing it lets wind roll aircraft and add drift |
| Severe bounce, or porpoise severe or getting worse | Go around immediately (TP 1102) |
| Late round-out, nose wheel down first, nose bounces up | Do not force it back down; go around (AFH ch.9) |
- Go-around: full power, keep direction, nose to safe climb attitude.
- Continue go-around even if it bounces again.
Trap: salvaging a bad bounce, or forcing aircraft onto runway while it still wants to fly. Airspeed drops fast nose-high, so aircraft may stall before next touchdown; forced contact sends it aloft again.
References
- AFH ch.9 (FAA-H-8083-3), Bouncing
- AFH ch.9 (FAA-H-8083-3), Porpoising
- TP 1102 Approach and Landing: Recovering from Bad Landings