Page:CAB Accident Report, United Airlines Flight 21.pdf/70

 attention of Captain Scott during this critical period. The evidence contains no indication of fire in the airplane prior to the time of impact. The condition of the wreckage shows that the isolated fires which started did so after the crash and witnesses saw no fire in the aircraft prior to the impact.

A substantial amount of testimony was also received as to whether ice was present on the airplane immediately prior to impact, and if so, what, if any, effect it could have had in contributing to the stall. It has been shown previously that ice on the wings raises the stalling speed of an aircraft to some degree, depending upon many varying factors. United 21 is known to have passed through an icing condition in the overcast and the examination of the aircraft after the accident showed ice on the wings. However, according to the testimony, the quantity of ice was not great and its position and type were not such as would ordinarily be expected to interfere substantially with the operation of the aircraft or to raise the stalling speed to any considerable extent. However, it is clear that the ice on the airplane did increase the stalling speed to some extent and that this condition was a contributing factor to the stall and the resulting crash in view of the other circumstances surrounding the approach which made all unfavorable factors affecting the approach, no matter how slight, extremely significant. In addition, the effect of the ice would be aggravated if Captain Scott did not know that he was carrying ice, or assumed that the ice was so negligible as not to affect the performance of his ship.

Testimony was also received as to the possibility that malfunctioning of the air speed indicators due to ice might have contributed to the accident