Page:CAB Aircraft Accident Report, United Airlines Flight 227.pdf/10

 resulted from impact loading in excess of their design structural strength.

No icing was encountered in the overcast, and there is no evidence of other circumstances which would unduly delay response from the three engines. Therefore, it is concluded that if power application had been initiated at the proper time, sufficient power would have been available to successfully complete the landing in the normal manner.

As the flight approached the Salt Lake City area, the crew was briefed on the new procedure and the location of the Lehi intersection. The captain, who had previously requested not to be vectored over Provo, selected a point 60 miles east of Lehi for commencing his descent. Subsequent vectors given to the flight resulted in a flightpath quite similar to that which the captain customarily took, and if anything was closer to Provo, and farther south than he would normally have gone. The flight passed the outer marker, 5.7 miles from the runway threshold, over 2,000 feet above the normal glide slope, at an airspeed of approximately 200 knots. The approach was continued and further speed reduction accomplished. In the ensuing seconds the landing configuration, 40 degrees flaps and landing gear down, and the reference speed for the approach were established. Approximately one minute prior to impact, the rate of descent was approximately 2,300 feet per minute, nearly three times the recommended rate of descent for landing approaches, and the aircraft was still 1,300 feet above the normal glide slope. The captain's testimony indicates that it was about this time that he advised the first officer to wait before adding power. He further testified that he realized he was in trouble at 1,000 feet and 1-1/4 miles from the runway. The flight recorder indicates this point was passed about 30 seconds prior to impact. He indicated that thrust lever movement to the takeoff power position had failed to bring a response from the engines, although he did not recall the engine instrument readings. It was his opinion that the best indication of engine response was "... the seat of the pants."

The time estimates between the captain's power application and impact varied markedly among the flight crew. However, it appears that the 5-10 second estimate of the first officer, and 7-8 second estimate of the second officer are more in, consonance with each other, and the testimony of eyewitnesses and passengers than the 30 seconds estimated by the captain. The physical damage to the No. 1 engine indicates that it was producing substantial thrust at impact. The foreign material ingested at that time penetrated all stages of the compressors and turbines. There was insufficient FOD in the Nos. 2 and 3 engines to accurately evaluate the power being developed at impact. However, there is no substantiation for slow response from either of these engines, and the Board believes they responded essentially the same as No. 1. The greater FUD in the No. 1 engine resulted from breakup of the air inlet cowl when it was struck by the left main landing gear. It is believed that the captain's estimate of full power application 30 seconds prior to impact is in error. If the thrust levers had been moved to the takeoff power position that early in the approach, the excess thrust would have been reflected in increased airspeed and/or decreased rate of descent.

UAL company procedures recommend that pilots where possible, maintain a descent with reference to the ILS glide slope. This will add in maintaining the suggested 6-800 feet per minute rate of descent on landing approaches. In addition the pilots are warned that, "'The highest rate-of descent tolerable with a flare from 50 feet is just under 2,000 fpm and requires takeoff power to keep the speed at 1.3 V$s$, during the flare.' Obviously this is a hazardous configuration and should