Hydroplanning
Hi Hetfield
Its been awhile since flying school! but here is the physics on hydroplanning, Its is mainly a factor of tire pressure. I dont fly Airbus products but I would imagine the Main wheel pressure would be around 130-150 psi, follwing this formula we could expect the hydroplanning speed to begin around 95 kts, that is wheel speed. Its very plausible that this AC never had any effective braking on the landing roll and that the crew was faced with no other option to try and execute a GA. With all the other factors involved ie TR locked out, newly paved ungrooved runway, the top coat still slippery, perhaps higher touch down speed ect... they may have been doomed from the beginning!! again this is all speculation at this point, but a realistic possibility which I am sure will be investigated by the authorities.
Quote from the FAA Flight Safety team
"When the runway is wet, you may be confronted with dynamic hydroplaning. Dynamic hydroplaning is a condition in which the airplane rides on a sheet of water rather than on the runway's surface. Because hydroplaning wheels are not touching the runway, braking and directional control are almost nil.
Three Types of Hydroplaning
There are actually three types of hydroplaning:
Dynamic - where the airplane rides on standing water;
Viscous - where a film of moisture covers the painted or rubber-coated portion of the runway; and,
Reverted, or melted rubber - where locked tires on a wet runway can cause heat so intense that the aircraft is actually riding on a mixture of steam and melted rubber.
For now, we'll concentrate only on dynamic hydroplaning.
To help minimize dynamic hydoplaning, some runways are grooved to help drain off water. However, most runways are not.
Tire pressure is a factor in dynamic hydroplaning. By this simple formula you can calculate the minimum speed, in knots, at which hydroplaning will begin. In plain language, the minimum hydroplaning speed is determined by multiplying the square root of the main gear tire pressure, in PSI, by nine.
For example, if your main gear tire pressure is at 36 pounds per square inch, you would begin hydroplaning at 54 knots.
Landing at higher than recommended touchdown speeds will expose you to a greater potential for hydroplaning. And once hydroplaning starts, it can continue well below the minimum, initial hydroplaning speed. "