Just because you’ve flown with some ice before doesn’t mean your aircraft will take off with what’s on the wing, now. Fine particles of frost or ice the size of a grain of table salt and distributed as sparsely as one per square centimeter over an airplane wing’s upper surface can destroy enough lift to prevent that airplane from taking off, the NTSB said. This kind of ice may not be seen in a visual check from the cabin, and it is difficult to see from the front or back of the wing. “The Safety Board believes strongly that the only way to ensure that the wing is free from critical contamination is to touch it,” the letter says. “The bottom line is that pilots should be aware that no amount of snow, ice or frost accumulation on the wing upper surface can be considered safe for takeoff.” Recent accidents indicate that the pilot community still may not appreciate the potential consequences of small amounts of ice, the NTSB said. Besides the Montrose crash, two other such accidents were the Oct. 10, 2001, crash of a Cessna 208 in Dillingham, Alaska, and a Jan. 4, 2002, crash of a Bombardier Challenger 604 in Birmingham, England. However, a careful and thorough preflight inspection, including tactile inspections and proper and liberal use of deicing processes and techniques, can ensure safe winter flying, the safety board said.
