Reply #8: Some clarity to your post [View All]

[maseman]

Yes the Q400 Bombardier turbo-prop has de-icing mechanisms on the wings and tail. Many planes, especially turbo-props, use a de-icing mechanism called "boots" which essentially pop with air burst that removes ice from the leading edges. (Other aircrafts, namely jets, use a weeping-wing which releases de-icing fluids through pores in the wings.)

A few problems with the "boot" mechanism. 1. Pilots can simply not use them usually due to not knowing they are in heavy icing conditions. It sounds by the tape recording that they did know there was icing. 2. In heavy icing situations sometimes a boot system is used too often which essentially forms an ice shell on the leading edge where the boot has fully inflated. Once that happens, which is rare, it is trouble for the airplane.

Icing conditions are probably one of the most risky parts of flying for a few reasons. It typically happens at lower altitudes where you have very moist air (clouds/fog) coupled with temps between about -5 c and 5 c. At higher altitudes it is usually both drier air coupled with colder temps which makes icing rare. Since an airplane encounters icing conditions at lower altitudes there is less room for error since the terrain is much closer. In the case of the Continental flight they had heavy icing. Once they went into their landing routine which requires flaps to be deployed the minimum safe airspeeds for wing stalls is dramatically increased. They most likely stalled the wings and since it was so low to the ground didn't have time to go into a spin or spiral. Thus landing flat on the house.

Very tragic. Ice is a tough problem. I am a private pilot in the north where we get tons of icing conditions. I have no de-ice equipment on my small single-engine plane so I am super-sensitive to icing conditions.