Aquaplaning
[1] Every vehicle function that changes direction or speed relies on friction between the tires and the road surface.
The tire then skates on a sheet of water with little, if any, direct road contact, and loss of control results.
What the driver experiences when a vehicle aquaplanes depends on which wheels have lost traction and the direction of travel.
If the drive wheels aquaplane, there may be a sudden audible rise in engine RPM and indicated speed as they begin to spin.
In a broad highway turn, if the front wheels lose traction, the car will suddenly drift towards the outside of the bend.
If the rear wheels lose traction, the back of the car will slew out sideways into a skid.
Electronic stability control systems cannot replace defensive driving techniques and proper tire selection.
These systems rely on selective wheel braking, which depends in turn on road contact.
While stability control may help recovery from a skid when a vehicle slows enough to regain traction, it cannot prevent aquaplaning.
Aquaplaning, also known as hydroplaning, is a condition in which standing water, slush or snow, causes the moving wheel of an aircraft to lose contact with the load bearing surface on which it is rolling with the result that braking action on the wheel is not effective in reducing the ground speed of the aircraft.
Aquaplaning has been a factor in multiple aircraft accidents, including the destruction of TAM Airlines Flight 3054 which ran off the end of the runway in São Paulo in 2007 during heavy rain.
Aquaplaning is a condition that can exist when an aircraft is landed on a runway surface contaminated with standing water, slush, and/or wet snow.
In 1965, a US delegation visited the Royal Aircraft Establishment at Farnborough to view their grooved runway for reduced aquaplaning and initiated a study by the FAA and NASA.
This can occur at a much lower speed than dynamic aquaplane, but requires a smooth or smooth-acting surface such as asphalt or a touchdown area coated with the accumulated rubber of past landings.
Dynamic aquaplaning is a relatively high-speed phenomenon that occurs when there is a film of water on the runway that is at least 2.5 mm (1⁄10 inch) deep.
Tests have shown that for tires with significant loads and enough water depth for the amount of tread so that the dynamic head pressure from the speed is applied to the whole contact patch, the minimum speed for dynamic aquaplaning (Vp) in knots is about 9 times the square root of the tire pressure in pounds per square inch (PSI).
Therefore, once a locked tire starts aquaplaning it will continue until the speed reduces by other means (air drag or reverse thrust).
[11] Reverted rubber (steam) aquaplaning occurs during heavy braking that results in a prolonged locked-wheel skid.
A side effect of the heat is it causes the rubber in contact with the runway to revert to its original uncured state.
Reverted rubber aquaplaning is insidious in that the pilot may not know when it begins, and it can persist to very slow groundspeeds (20 knots or less).
