leading edge and upper surface. The aircraft was evaluated by ground crew and was deiced. After the mechanical failure of the deicing truck, the investigators reported that, as the captain requested another deice, he was: ... concerned about the continuing exposure to precipitation, and the request was prudent and in accordance with USAir guidance. Following the second deicing, the flight crew was most likely satisfied that the airplane was free of adhering contamination. The flight crew was not aware of the exact delay that they would encounter before takeoff and their decision to leave the gate was reasonable. After taxiing, when it became evident that they would be delayed for a prolonged period, conversations between the crew showed that they were aware of and probably concerned about the risk of reaccumulating frozen contamination on the wing. They also found that USAir guidance and flight-crew training was sufficient and should have alerted the flight crew to the risk of attempting a takeoff while they were unaware of the condition of the wing. USAir guidance to flight crews specifically stated: ... it is the captain's responsibility to exercise caution prior to takeoff. If the elapsed time since deicing exceeds 20 minutes, careful examination of the surfaces should be conducted to detect the extent of accumulation [of ice] and to assure that the takeoff can be made safely and in compliance with existing [regulations]. The final report read: The Safety Board believes that the flight crew of Flight 405 should have taken more positive steps to assure a contamination-free wing, such as entering the cabin to look at the wing from a closer range. Although the Safety Board acknowledges that the detection of minimal amounts of contamination, sufficient to cause aerodynamic performance problems, is difficult and may not be possible without a tactile inspection, an observation from the cabin would have improved the chance of seeing some contamination and might have prompted the flight crew to return to the gate. The Safety Board believes that the flight crew's failure to take such precautions and the decision to attempt takeoff while unsure of wing cleanliness led to this accident and is a cause of it. In a television interview, one of the NTSB investigators suggested, "the captain was faced with quite a problem. If he wanted to be deiced a third time, he would have had to get out of the line [of jets