What are some factors to keep in mind while flying in the winter?
- Anticipate the possibility of fuel selector valve freeze-up (switch to another tank periodically)
- Keep the engine warm during descent and avoid sudden power reductions
- Check runway conditions and braking action (if no notams, call ahead)
- Snow covered runways lack contrast with their surroundings
- Use all available navaids and lighting (on every landing)
How are braking action report received?
They are given to you by ATC when reports have been received from pilots or airport management. (reported as good, fair, poor, and nil
What is needed when making a braking action report?
- use of appropriate descriptors
- what part(s) of the runway are affected
- type of aircraft
When braking action reports include “poor” or “nil”, what will the pilot hear on the ATIS?
“breaking action advisories are in effect”
Explain MU, and the significant numbers.
MU is used to designate a friction value representing runway surface conditions (between 0 and 100).
MU = 40, the level when the aircraft braking performance starts to deteriorate and directional control begins to be less responsive.
What is dynamic hydroplaning?
Occurs when standing water on a wet runway is not displaced from under the tires fast enough to allow tire to make a pavement contact over its total footprint area.
The tire rides on a “wedge” of water under part of the tire surface. It can be partial or total. The speed at which dynamic hydroplaning begins is: V (knots) = 9 * [EP]^(1/2), where EP is tire inflation pressure
What is viscous hydroplaning?
Can cause complete loss of braking action at a lower speed if the wet runway is contaminated with a film of oil, grease, rubber, or the runway is smooth. The contamination combines with the water to create a most slippery surface. It can occur at a water depth less than that required for dynamic hydroplaning, and at a lower speed (while taxiing)
What is rubber reversion hydroplaning?
Cause by the friction-generated heat that produces superheated steam at high pressure in the tire footprint area. The high temp. causes the rubber to revert to its uncured state and form a seal around the tire area that traps the high-pressure steam. May lead to tire failure.
What are some things to consider with regards to hydroplaning?
- don’t hesitate to delay landing
- consider:
Landing weather forecast
Aircraft weight and approach speed
Hydroplaning speed
Condition of tires (if the tread depth is greater than the depth of water on the runway, hydroplaning will not occur)
Glide path angle
Brake characteristics
Wind effects on the aircraft while landing
Runway length and slope
How can you minimze hydroplaning?
- do not exceed Vref or 1.3 Vso plus wind additives
- use maximum flaps to provide minimum approach speed
- do not perform a long flare
