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equipment, approach lights, and marker beacons were operating normally at all times during the afternoon of the crash. The Airway Traffic Control personnel of the Civil Aeronautics Administration at Chicago handled the flight with marked diligence and efficiency. The basic responsibility of Airway Traffic Control is to prevent aerial collisions between aircraft operating under instrument conditions. Decisions on whether a flight is advisable, or may be made with safety, under the weather conditions existing are the responsibility of the pilot and the air carrier dispatcher. Notwithstanding this, Airway Traffic Control suggested to the United dispatcher that he advise Captain Scott that an air carrier airplane which has preceded him had accumulated an inch and a half of ice while coming through the overcast. In addition, while it is the usual Airway Traffic Control procedure to bring aircraft into an airport by stepping them down through 1000-foot levels, Airway Traffic Control varied this procedure in the case of United 21 in order to avoid holding the trip in icing conditions while awaiting a clearance to land. Captain Scott was told to hold at 6000 feet until Airway Traffic Control could give the trip an approach clearance so that it might descend through the overcast as rapidly as possible. Thus, when the trip was cleared to descend, it was necessary for it to spend only about 8 minutes in the overcast where icing conditions prevailed. Airway Traffic Control also attempted to expedite landings by giving incoming traffic priority over departures during this period.
A substantial amount of testimony was received at the hearing as to the handling of the flight by the Airport Control Tower, which is operated by the City of Chicago through its own employees. Mr. John N. Becker, Chief Control Tower Operator, was in charge on the evening of the crash.
