Recognizing & handling hydroplaning
Recognizing it (TP 1102 Take-off: Hydroplaning). Suspect hydroplaning when:
- raindrops appear to bounce off the runway, or
- runway depressions pool water in heavy rain or a spring thaw.
Light or moderate rain seldom leaves enough standing water on a well-drained runway to hydroplane (TC AIM AIR 1.6.6).
Once it starts (TC AIM AIR 1.6.6; TP 1102 Approach and Landing: Wet Runways Hydroplaning):
- Water film keeps tyre separated until speed falls well below onset speed.
- Traction almost negligible; wheel may stop rotating.
- No braking, no directional control.
| Effect | Magnitude |
|---|---|
| Stopping distance | Up to 700% longer |
| Drift in 10-kt crosswind | Off a 200-ft wide runway in about 7 sec |
Handling it:
| Phase | Hydroplaning | Action | Cite |
|---|---|---|---|
| Landing | Possible | Land on grooved runway if available; touchdown speed as slow as consistent with safety | AFH ch.9 |
| Landing | Suspected | Release brakes, reapply very slight pressure, increase gradually as aircraft slows; repeat as needed | TP 1102 Approach and Landing: Wet Runways Hydroplaning |
| Take-off | Suspected | Be ready to control aircraft without brakes after about 30 kt groundspeed | TP 1102 Take-off: Hydroplaning |
Trap: assuming brakes work once tyres float (traction is gone), or that any rain makes a runway hydroplane.
References
- TC AIM AIR 1.6.6
- TP 1102 (Flight Training Manual)
- AFH ch.9 (FAA-H-8083-3), grooved runway landing