Definition
A condition in which a tire rolling on a wet runway loses contact with the surface because a layer of water builds up between the tire and the pavement, dramatically reducing braking effectiveness and directional control. Three forms are recognized: dynamic hydroplaning (water pressure lifts the tire off the surface at speed), viscous hydroplaning (a thin film of water on a smooth surface prevents tire contact), and reverted rubber hydroplaning (heat from a locked, skidding tire turns trapped water to steam and reverts the rubber to its uncured state).
Plain English
When the runway is wet, the tires can ride up on top of the water like a water ski instead of gripping the pavement. When that happens, brakes and steering through the wheels do almost nothing.
Context Anchor
Pilots encounter hydroplaning during takeoff, landing, or braking on a wet runway, especially where standing water is present.
Derivation
From the Greek hydro (water) plus plane (to glide or skim, as in 'aquaplane'). The word literally means 'water-skimming' — a useful image, because the tire is doing exactly that: gliding on top of the water rather than rolling through it.
Why Pilots Care
Hydroplaning can cause sudden loss of steering and braking, leading to runway excursions or loss of directional control.
Analogy
It is like a car tire hitting a deep puddle and suddenly feeling light and loose. The tire is no longer gripping the road well because water is between the tire and the surface.
Grounding Statement
Picture landing on a runway with standing water: if the tires cannot push the water out of the way fast enough, they can skate on the water instead of biting into the pavement.
Intuition Check
Hydroplaning does not mean the airplane is floating in the air. It means the tires are losing contact with the runway because water is getting between the tires and the surface.
Example Sentence 1
After landing on the rain-soaked runway, the pilot avoided heavy braking until the airplane had slowed below the hydroplaning speed.
Example Sentence 2
After heavy rain the crew waited for the runway to drain to reduce the chance of hydroplaning during landing.