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Minutes Prior To Crash

From Civil Aeronautics Board Aircraft Accident Report:

“…the flight operated without any reported difficulties to Holston Mountain VOR. The crew reported to the Atlanta Air Route Traffic Control Center over that fix at 1758:35 and estimated their arrival in Knoxville at 1821. Approximately one minute after having reported passing Holston Mountain, the crew requested a clearance to descend to the lowest available altitude. They were cleared to descend to 8,000 feet. Three minutes later the crew cancelled their IFR clearance. The controller offered to pass control of the flight to Knoxville Approach Control when they were closer in and advised they could stay on the Center frequency. At 1802:55 the crew responded to this transmission with “OK”. This was the last known transmission from the aircraft… Flight 823 was first observed approximately 38 miles south west of Holston Mountain VOR at an estimated altitude of 5,000 feet descending. There was no visible difficulty at that time. A witness who observed the aircraft from a position 11 miles northeast of the crash site was the first to report seeing anything unusual. She noted a violet red light burning on the fuselage. She could offer no further clarification as to the location of this light. While she could read the company name on the side of the aircraft, she did not see any smoke. The time was about 1810 and the aircraft was estimated to be at an altitude of 500 feet… The crash occurred approximately 41 nautical miles east-northeast of the Knoxville VORTAC and about 2 1/4 miles Northeast of Parrottsville, Tennessee at approximately 1815. The accident occurred during daylight hours at an elevation of approximately 1,400 mean sea level (m.s.l).”

A Review

From Holston Mountain VORTAC (36-26-13.396N 82-07-46.462W) Victor 16 Airway intersects at the Ottway Intersection (36-13-03.060N 82-52-15.860W) , as mentioned on Page 6 of the Civil Aeronautics Board Aircraft Accident Report.

It is important to note that the Appalachian Mountains generally run from Northeast to Southwest. The flight was heading in a direction of Southwest, parallel to the general direction in which the mountains run.

The mountain range that is called Bays Mountain would appear on the Flight Crew's right hand side, in the general direction of north.

Another range of mountains, most notably a mountain named Camp Creek Bald, form the North Carolina/Tennessee state line and would appear on the flight's left, in a southerly direction. These provide a very wide valley, with the two mountain ranges providing excellent landmarks or points of reference to within sight of Knoxville. Present day Interstate Highway 81(non-existent in 1964) runs roughly straight down the middle of the valley, slightly to the north of Ottway, Tennessee.

The flight was observed on radar to pass Holston Mountain VORTAC (36-26-13.396 N / 82-07-46.462W) at 1757. Up until then there were no indications that United Flight 823 was experiencing difficulties.

At 1802:55, the crew gave its last transmission of “OK”. This would have been nearly 6 minutes after radar detected the airplane passing the Holston Mountain VORTAC at 1757.

According to the C.A.B report, “ The aircraft should have been at approximately 11,000 feet and about 24 miles southwest of Holston Mountain when they cancelled 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 feet m.s.l) above the terrain and the aircraft appeared to be normal at this time. The aircraft appeared to be normal at this time. The aircraft appeared to be following a nearby river and was about 8 miles south of the airway centerline.”

There are two major rivers in the vicinity. The Holston River runs to the north of Bays Mountain (which would be on the opposite side of Bays Mountain away from the aircraft). The other is the Nolichuckey River that originates in North Carolina. It runs along the foot of Camp Creek Bald and the range of mountains that comprise the Tennessee/North Carolina state line. If one takes a ruler and measures the mileage scale on an ordinary road map, it is plain to see that the report meant the river as being the Nolichuckey which would be approximately eight miles south of the V16 centerline.

According to the Civil Aeronautics Board Report, both the primary and secondary radar targets disappeared at 1813:30, precisely 15 minutes and thirty seconds after passing Holston Mountain and approximately 10 minutes and 30 seconds after the crew's last radio transmission.

What transpired during those ten and a half minutes?

When the aircraft was first sighted from the ground it was 38 miles from Holston Mountain and 18 miles from the crash site, at an approximate altitude of 5,000 feet m.s.l. It was descending and, if the approximation of altitude is near accurate, had gone beneath the 8,000 foot minimum altitude for which it had received clearance. Thus, it is safe to assume that the aircraft was already in trouble by that time.

From a position 11 miles from the crash site, a witness saw a “violet red light” burning on the fuselage. She could read the “United” name on the side of the aircraft and she estimated the plane's altitude as being 500 feet. She did not notice smoke coming from the plane. The approximate time was 1810.

Since the crash occurred at 1813:30, it took the plane 3.5 minutes at an extremely low altitude to travel its final 11 miles.

From Civil Aeronautics Board Aircraft Accident Report Page 13:

“The average rate of descent from initiation to level off at an estimated 500 feet above 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 237 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.”

Captain Oliver E Sabatke

United Flight 823

the_minutes_prior_to_crash.txt · Last modified: 2014/01/26 01:03 by tom

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