Landing on wet and short runways

Water on a runway changes how an aircraft stops. The FAA's training handbook, written for pilot training and mostly about light aircraft, says that on a runway with standing water, slush or wet snow, hydroplaning can seriously affect steering on the ground and braking.^[1]

Three kinds of hydroplaning

• Dynamic hydroplaning needs a film of water at least one-tenth of an inch deep. At the hydroplaning speed the tyre is lifted off the runway and braking action is nil. The FAA gives the minimum speed as 8.6 times the square root of the tyre pressure in pounds per square inch.^[1]
• Reverted rubber hydroplaning follows heavy braking with a locked wheel: the heat turns the water under the tyre to steam.^[1]
• Viscous hydroplaning needs only a film no more than one-thousandth of an inch deep on a smooth surface, such as asphalt or a touchdown area coated with rubber from earlier landings. Such a surface can be as slippery as wet ice.^[1]

Where hydroplaning is possible, the handbook advises landing on a grooved runway if there is one, at a touchdown speed as slow as is safe.^[1]

Short runways

Short-field procedures apply where the landing area is relatively short or obstacles on the approach limit it. Speed is the main concern: too much of it on final approach makes the aircraft float, and it may then pass the planned touchdown point with too little runway left. The FAA says prolonged floating should be avoided especially on short runways or in strong crosswinds.^[1]