The NTSB has issued an Alert to Pilots: Wing Upper Surface Ice Accumulation. This advisory follows in the aftermath of the November 28, 2004 crash of a Bombardier Challenger 604 in Montrose, CA. The NTSB’s preliminary investigation into the accident has revealed “that atmospheric conditions conducive to upper wing surface ice accumulation existed at the time of the accident”.
The advisory discusses several accidents involving upper wing ice accumulation and also research that has been conducted regarding the effects of upper wing ice accumulation on aircraft performance. The NTSB notes that “it is critically important to ensure, by any means necessary, that the upper wing surface is clear of contamination before takeoff. That is why the Safety Board recently issued Safety Recommendation A-04-66, urging pilots to conduct visual and tactile inspections of airplane wing upper surfaces.” In the NTSB’s opinion, “no amount of snow, ice or frost accumulation on the wing upper surface can be considered safe for takeoff.”
The bottom line is that pilots have to both “look” at the wings and “touch” them to confirm that no ice or other contamination has accumulated on the upper wing surface. If it has, removal is required before takeoff. Extra vigilance is required during the winter months to ensure flight safety.