Ask the Captain: Is there a better way to de-ice?
Q: Capt. Cox, thank you for your informative column. I believe aircraft have de-icing mechanisms. What is the difference between these and, say, a windshield defroster, and why couldn't they be used in place of having wings sprayed with de-icing solution?
— Dan Parker, Brantford, Ontario, Canada
A: Glad you enjoy the column. I enjoy the questions.
Inflight de-icing equipment de-ices only the leading edges of the wings, propellers and sometimes the tail. Other parts of the airplane, such as the windshield and pitot tubes, are heated to prevent ice buildup.
On the ground, ice forms on the entire surface of the airplane, resulting in significant weight and the distortion of the airflow, which is potentially dangerous. Consequently, ice must be completely removed from the airplane before takeoff. Heated fluid knocks the ice off the airplane, then a thick gel is applied, so any ice or snow that falls will not stick to the airplane and will blow off during the takeoff roll. This gel is effective for only a limited time, requiring pilots to refer to tables to determine how long the period between de-icing and takeoff can be.
Trying to heat the entire airplane would require a very large amount of hot air and a very heavy mechanism; therefore, it is not efficient.
Q: On a recent flight out of Chicago, it began to snow lightly as we sat at the gate and then just before takeoff. I noticed some flights were getting de-iced, but we did not. As we took off, we threw loose snow for about 5 minutes, then we got out of the clouds and into clear air. I was sitting on the wing, and it looked shiny like ice, so this concerned me. Should we have been de-iced?
— Rob, St. Louis
A: It is impossible to answer your question with limited information. If there was contamination (snow in your case) adhering to the wing, then de-icing was required. If, however, there was only dry snow on the wing that was not adhering, then de-icing was not required. Once airborne, the airplane’s anti- and de-icing system would eliminate any icing concerns.
Q: You are going to laugh at this one. I was a USAF pilot and a commercial pilot. I have a lot of B-52 hours, much of it at Kincheloe AFB. As crazy as this may seem, the USAF never de-iced our planes. They did sweep the snow off the wings. The engines had bleed air anti-ice for the cowling, and the windshield had electrical. We were told the wings were so flexible the ice would crack off. It apparently worked, but do you believe that?
— Doug Constantine, Cape Coral, Fla.
A: I have never heard of using wing flexing for ice removal. If that was done in the past, it was certainly a unique solution and one we probably would not use today.
John Cox is a retired airline captain with US Airways and runs his own aviation safety consulting company, Safety Operating Systems.