Ask the Captain: How safe is landing in snow and ice?
Question: In freezing conditions, with ice on the runway, how safe is the anti-skid braking system on a modern jet? Was there any time you rejected a landing due to ice/snow on the runway?
— Submitted by reader Robert Clark
Answer: The modern jet’s anti-skid system is very good. I have landed on ice-covered runways many times using the anti-skid system to safely stop the airplane.
Pilots listen carefully to other landing airplanes for descriptions of the stopping ability on the runway. Runway conditions can change quickly, requiring judgment and experience by the pilot to determine whether it is safe to proceed. This system has worked very well for many decades to ensure the safety of landing aircraft.
Yes, I have rejected a landing due to runway conditions. When an aircraft ahead reported the braking action as nil or very poor, I have diverted to an alternate runway or airport.
Q: I have noticed that once a plane lands, certain rear part of the wings move up and down. What does that do?
— Ralph Polanco, Norwalk, Conn.
A: You are describing spoilers on the wing. After touchdown, the spoilers rise up from the wing, causing lift production to nearly cease. The weight of the airplane transfers to the wheels, making the braking much more effective and allowing the airplane to stop within the length of the runway. This is particularly important when the runway is contaminated with water, ice or snow.
Q: When using reverse thrust, does the pilot control the amount of thrust, or is that preset by the engine manufacturer? And which do you personally prefer to stop with, brakes or reverse thrust?
— Scott Lineberger, Jacksonville
A: The pilot can increase the amount of reverse thrust using sub throttles located on top of the throttles or after moving the throttles through the reverse “gate.” It is up to the pilot. My personal choice on a dry runway is limited reverse thrust and minimal autobrake. On a wet runway, more reverse thrust and a higher setting on the autobrake. Reverse thrust is also an important factor when landing in ice or snow.
Q: My flight was canceled due to snow at the airport, but many other flights are departing. Why?
— Submitted via email
A: There can be many factors that can cause the cancellation of a flight. Airline weather policies may vary, making it possible for one airline to cancel operation while others continue to operate.
John Cox is a retired airline captain with US Airways and runs his own aviation safety consulting company, Safety Operating Systems.