Page:CAB Aircraft Accident Report, United Airlines Flight 227.pdf/6

 1.7 Meteorological Information

The 1755 surface weather observation at Salt Lake City was in part: 7,000 feet scattered, estimated ceiling 10,000 feet broken, 14,000 feet overcast, visibility 25 miles, temperature 44F, dewpoint 27F, wind 350 degrees 3 knots, altimeter setting 30.06 inches.

The 1615 Salt Lake City radiosonde ascent showed conditionally unstable air and increasing moisture from the surface to approximately 9,800 feet m.s.l., stable air above 9,800 feet, and moist air from that level to 27,000 feet. The freezing level was at 7,800 feet m.s.l. The crew reported that no icing was encountered.

Although no formal weather briefing occurred, the crew did refer to the self-help weather briefing boards prior to departure from Denver.

1.8 Aids to Navigation

All components of the ILS serving Runway 34L were operating within acceptable tolerances, and the crew stated that both receivers were tuned to the ILS during the final approach.

1.9 Communications

All transmissions from the flight were made by the captain. There were no reported problems with communications.

1.10 Aerodrome and Ground Facilities

Runway 34L is 10,000 feet long, 150 feet wide with a concrete and bituminous surface, and is equipped with high intensity runway lights and a standard approach lighting system. Both systems were operating and set properly at the time of the accident.

1.11 Flight Recorder

The flight data recorder on this aircraft, a Fairchild Model 5424, S/N 1540, was examined and there was no fire or mechanical damage found. The tape was in excellent condition and all parameters were functioning. The flight record was read out for the last 15 minutes. Approximately 14 minutes prior to impact a high speed descent from the cruising altitude of FL 310 began. The reduction in speed from 370 knots began at 10,200 feet, approximately 4-1/2 minutes from impact, as the descent continued. A stabilized approach speed of 123 knots was reached at 7,800 feet with slightly less than two minutes to impact. During the last 4-1/2 minutes of the approach the rate of descent exceeded 2,000 feet per minute and averaged in excess of 2,300 feet per minute in the last minute. At initial impact a vertical acceleration of +4.7-g occurred, and the other three parameters apparently did not scribe for a six-second time period. Although the acceleration peaks during the next several seconds reached total amplitudes of -1 to +6-g's, some aberrations did occur.

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