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Captain Richmond also testified that he had experienced conditions where the hot air blower system was not capable of freeing the windshield of ice. In these cases, he was forced to open the side window and scrape the ice off with a putty knife. However, he stated he was never prevented from opening the sliding part of the windshield because of ice.
From the evidence available, it is concluded that an icing condition existed in the overcast in the vicinity of the Chicago Municipal Airport at the time of the accident. This condition was variously described by pilots as light to heavy and of both rime and glaze types of ice, and was especially pronounced at the 4000 to 3000-foot level. Although the evidence is conflicting, it appears probable that a light icing condition existed under the overcast.
CONDITION OF THE AIRPLANE AND EQUIPMENT IMMEDIATELY PRIOR TO IMPACT
In seeking to determine the condition of the airplane and its equipment immediately prior to impact, we are particularly fortunate in that the trip log for United 21 between LaGuardia Field and Chicago was completed by First Officer Young, except for the insertion of the landing time at Chicago, prior to the accident and was recovered in the wreckage. It is impossible to reach a definite conclusion as to the exact point in the flight at which First Officer Young made his last entry in the trip log, but it is a reasonable assumption that the trip had at least reached the vicinity of the Chicago Airport before the final notations were inserted in the log. This log indicates that the airplane, engines, radio, and instruments were operating normally.
In addition, the flight crew of United 21 made a number of radio contacts just prior to the accident with the United Radio operator and the airport
