Page:CAB Accident Report, United Airlines Flight 21.pdf/64

 Scott was furnished with the 4:35 Chicago weather observation, the 5:10 special Chicago weather observation, and at 5:28 was advised by the United radio operator at Chicago that Airway Traffic Control had reported that a flight while in the overcast over Chicago had accumulated 1-½ inches of ice. From the evidence with respect to the operation of that portion of the flight between LaGuardia Field and Cleveland, it may be concluded that the dispatcher in charge of the flight performed his duties properly. Moreover, there is no evidence that the dispatcher at Chicago failed to perform his duty properly in clearing the trip from Cleveland to Chicago since the weather at that time at Chicago was not such as to require cancellation.

The question still remains whether after the present flight arrived at the Chicago Airport it should have been permitted by the dispatcher to land.

At the time Trip 21 arrived at the Chicago Airport, the ceiling was 900 feet and the visibility about one mile with occasional snow and drizzle present under the overcast. The conditions of ceiling and visibility were above the minimums prescribed by the Civil Aeronautics Administration for night landings at the Chicago Airport. It should be noted that these minimums, which are prescribed in the weather competency letter of the air carrier operating certificate, do not constitute a standard for the exercise of discretionary judgment by dispatchers or pilots; they provide an absolute prohibition against landing when the required conditions are not present, thereby precluding the exercise under such circumstances of any judgement by dispatchers or pilots. United Air Lines correctly interprets the ceiling and visibility