Adverse Conditions Flight Technique

Question 0

What types of aquaplaning are there?

Answer 0

There are three types of aquaplaning:

• Dynamic
• Viscous
• Reverted Rubber

Question 1

What is aquaplaning?

Answer 1

Aquaplaning is the lifting of the tyre off the ground due to build up of water underneath it, caused by factors such as high speeds, tyre pressures, and braking pressure. The tyre is no longer in contact with the rwy and can therefore not aid in slowing or controlling the aircraft.

Question 2

What is dynamic aquaplaning?

Answer 2

Dynamic aquaplaning is caused by high aircraft landing speeds and water on the runway with a thickness of 2.5 mm or more. Due due the water not being able to move aside underneath the tyre, for reasons such as u grooved rwy or minimal tread on the tyres, it start building up, creating a layer of water between the tyre and the rwy. This prohibits contact of the tyre with the rwy reducing braking action and controllability.

Question 3

What is viscous aquaplaning?

Answer 3

Viscous aquaplaning is similar to dynamic aquaplaning but with the difference that only thin layers of water (0.025mm) and lower landing speeds cause this type of aquaplaning. Smooth surfaces, such as touch down areas, are usually associated with viscous aquaplaning.

Question 4

What is reverted rubber aquaplaning?

Answer 4

Reverted rubber aquaplaning is caused by high speed landings with locked tyres, which in turn heats the water and tyres near the contact surface. A thin layer of steam then lifts the tyre off the ground. Further the rubber off the tyres reverts back I to it’s original state of a soft rubber creating another surface upon which the aircraft slides on.

Question 5

What is the formula for the speed at which a locked tyre starts aquaplaning?

Answer 5

V= 7.7 x square root of tyre pressure.

Question 6

What is the formula for the speed at which a rolling tyre starts aquaplaning?

Answer 6

V= 9 x square root of tyre pressure.

Question 7

How does the tyre pressure affect an aircrafts aquaplaning characteristics?

Answer 7

The lower the tyre pressure, the greater the contact surface is on the ground. This allows the more water to collect underneath the tyre, eventually lifting the aircraft off the rwy. This occurs at lower landing speeds.
On the other hand a properly inflated tyre penetrates the water surface easier, allowing it to make contact with the rwy and increase braking efficiency.

Question 8

How can the risk of aquaplaning be reduced?

Answer 8

• Proper tyre inflation
• Proper approach speeds (Not too fast)
• Avoiding landing on wet/contaminated rwy
• Minimize the use of brakes during the landing; use reverse thrust if possible
• Use of proper braking technique (similar to ABS)
• ABS brakes on aircraft