Page:CAB Accident Report, United Airlines Flight 21.pdf/33

 Weather observations were made by the Chicago Weather Bureau Airways Station at intervals of about 15 minutes from 3:35 p.m. until after the accident. These reports were available over the teletype circuits to United's dispatchers and meteorologists and were available to Captain Scott by simultaneous radio range broadcasts.

The 3:35 weather observation reported the ceiling at 1000 feet, an overcast sky with scattered clouds at 600 feet, a visibility of 2 miles with light smoke, a temperature of 33 degrees, a dewpoint temperature of 31 degrees, with a wind from west northwest of 11 miles per hour.

The 3:53 weather observation reported no change from the 3:35 report. The 4:10 weather observation reported the ceiling at 1000 feet, an overcast sky with scattered clouds at 600 feet, a variable visibility of 1¼ miles, with a light freezing drizzle and light smoke, a temperature of 33 degrees, a dewpoint temperature of 31 degrees, with a wind from the west northwest of 11 miles per hour, and included a pilot report locating the top of the overcast at 5000 feet and light to moderate icing existing between 1000 and 5000 feet.

The 4:20 weather observation reported no change since the 4:10 report. The 4:35 weather observation reported the ceiling at 1000 feet, and overcast sky with scattered clouds at 600 feet, a visibility of 1 mile, with light drizzle, light fog and light smoke, a temperature of 33 degrees, a dewpoint