Page:CAB Accident Report, United Air Lines Flight 823.pdf/13

 1.16

Investigation of insurance purchased by passengers and crewmembers disclosed no suspect areas. Nothing unusual was noted regarding the passengers or baggage that went aboard the aircraft and there was no known hazardous cargo aboard the aircraft.



2.1

Crew training and certification were not considered to have a causal relationship to this accident. The weight and c.g. of the aircraft was within limits at takeoff and computed to have stayed within limits until the crash. There was no evidence that the weather, sabotage by explosion, any failure of the powerplants, or the primary aircraft structure played a part in this accident. The Air Traffic Control handling of the aircraft was routine throughout the flight. There is no evidence of improper aircraft maintenance or that the aircraft was not airworthy at the time of its departure from Washington.

There was no indication of any difficulties aboard the aircraft until after it passed Holston Mountain VOR. Having passed the VOR, the crew began a normal en route descent in VFR conditions that would have brought them into the Knoxville area at a reasonable altitude to maneuver for a landing. Their descent was probably normal, i.e., approximately 1,000 feet per minute until they canceled their IFR flight plan at 1802:45. There was nothing in their transmissions to indicate they were having any difficulty at that time. The aircraft should have been at approximately 11,000 feet and about 24 miles southwest of Holston Mountain when they canceled their IFR flight plan.

At some time during the descent, the aircraft deviated to the south of V16 but was proceeding approximately parallel to the airway. No reason can be assigned to this deviation. The first witness believed to have seen the aircraft was 38 nautical miles southwest of Holston Mountain. He estimated the aircraft to be 4,000 feet (approximately 5,500–6,000 m.s.l.) above the terrain and the aircraft appeared to be normal at this time. The aircraft appeared to be following a nearby river, in a descent, and was about 8 miles south of the airway centerline. Three miles farther along the flightpath, at approximately 1810, the aircraft was observed about 500 feet above the ground. The aircraft continued to operate at very low altitudes and well to the left of the airway from this point on to the crash. The average rate of descent from initiation to level off at an estimated 500 feet above the ground was about 1,200 ft./min. and the average ground speed was 174 knots from initiation of the descent to impact. This indicated that the flight's airspeed was reduced from a cruising speed of 247 knots to some lower value and that the descent was continued to an altitude above the ground lower than that normally utilized in transport operation.

It is believed that the crew discovered a fire sometime during the period between cancelling their IFR and before being observed in a descent about 4,000 feet above the ground.

As previously stated there was extensive fire damage in the electrical bay. However, this fact alone cannot be considered significant. This area in the