United Air Lines Flight 823
| United Air Lines Flight 823 | |
|---|---|
 The affected machine in 1963 |
|
| Accident summary | |
| Accident type | Loss of control after cabin fire |
| place |
Cocke County , near Parrotsville , Tennessee , United States
|
| date | July 9, 1964 |
| Fatalities | 39 |
| Survivors | 0 |
| Aircraft | |
| Aircraft type |
 Vickers Viscount 745D
|
| operator |
United Air Lines
|
| Mark |
N7405
|
| Departure airport |
Philadelphia Airport , Pennsylvania , United States
|
| 1. Stopover |
Washington National Airport , Arlington County , Virginia , United States
|
| 2. Stopover |
Knoxville Airport , Tennessee , United States
|
| Destination airport |
Huntsville International Airport , Alabama , United States
|
| Passengers | 35 |
| crew | 4th |
| Lists of aviation accidents | |
On July 9, 1964, a Vickers Viscount 745D crashed on United Air Lines flight 823 (flight number: UA823 ) near Parrotsville in Cocke County in the state of Tennessee , USA . A fire had previously broken out on board the machine. All 39 people on board were killed in the accident.
plane
The accident Vickers Viscount 745D with the model serial number 103, which had completed its maiden flight on November 3, 1955, was originally delivered to Capital Airlines , where it was registered with the aircraft registration N7405 and received the fleet number 324 . In June 1961, Capital Airlines was taken over by United Air Lines , whereupon the machine was transferred to their fleet. The aircraft was equipped with four turboprop engines of the type Rolls-Royce Dart 510 equipped and had up to the time of the accident completed 23,804 hours of operation.
the accident
United Air Lines Flight 823 was a scheduled flight from Philadelphia International Airport in Pennsylvania to Huntsville International Airport in Alabama . Stopovers were scheduled at Washington, DC and Knoxville , Tennessee .
The first leg of the flight to Washington DC was flown without incident. After the stopover, the aircraft took off at 4:36 p.m. for the onward flight to Knoxville, the scheduled arrival time was 6:13 p.m. Here, too, initially no difficulties were reported by the crew. Pilots reported to the Air Route Traffic Control Center in Atlanta at 5:58 pm , stated they had just passed the Holston Mountain radio beacon in Tennessee, and gave their estimated time of arrival in Knoxville 6:21 pm.
About one minute after the last radio message, the co-pilot of the Viscount reported and asked for clearance to descend to the lowest possible available altitude. Air traffic control gave clearance to descend to 8,000 feet (approx. 2,440 meters), and the crew was instructed to maintain this altitude afterwards. The crew revoked their instrument flight clearance three minutes later .
The air traffic controller in Atlanta offered the crew to hand over the monitoring of the flight to air traffic control in Knoxville as soon as the aircraft had approached the airport further. At 18:02, the crew of the Viscount replied with “OK”. This was the last radio message from the crew. The aircraft's radar echo disappeared from the air traffic controller's radar display at 18:13:30 . After the radar device had made four antenna revolutions, the air traffic controller called the aircraft again at 6:14 p.m. and indicated that the radar contact had broken off. He received no answer to this radio message.
It was later speculated that the crew discovered a fire on board their plane shortly after their last radio message. The Viscount was later sighted at an altitude of 4000 feet (approx. 1220 meters). It deviated from its approach route southwards, but continued to descend parallel to the intended course. At around 6:10 p.m., she was sighted at an altitude of approximately 800 feet (about 250 meters). At this point the machine was pulling clouds of smoke behind it. It was moving at a very low altitude and now deviated more and more to the left from its flight route.
A passenger jumped out of the aircraft through emergency exit window no. 4 around 3 kilometers before the impact. He just fell to the ground but did not survive the impact after the free fall.
Shortly afterwards it was observed how the angle of attack of the machine increased significantly. Shortly afterwards, the nose of the aircraft dropped, the machine rolled to the left and fell to the ground. Around 6.15 p.m. local time, the Viscount hit the ground 2.25 nautical miles northeast of Parrottsville, Tennessee, exploded and burned out.
root cause
The investigation into the cause of the crash was conducted by the Civil Aeronautics Board (CAB). It came to the conclusion that the likely cause of this accident was an uncontrollable fire of indeterminate origin during the flight in the fuselage, which resulted in a loss of controllability of the aircraft. The source of the fire could not be identified. By examining the clothing of the jumped passenger, among other things, the investigators came to the conclusion that the fire must have originated in the passenger compartment.
Reactions
United Air Lines initially did not want to believe that a passenger could have jumped off in flight, especially since the cabins of aircraft are usually under pressure during a flight , which means that doors and hatches cannot be opened. In the course of the investigation, it was finally found that the pressure valve had been opened on board due to the fire emergency.
consequences
The complicated accident investigations triggered a further development of the Lockheed L-109C flight data recorder built into the machine . As a result, these devices were modified and new standards for flight data recorders in general were introduced.
Another source of error that was investigated was the Pyrene Duo Head DCD-10 CO 2 fire extinguishing system installed in the cargo compartment . A corresponding airworthiness directive has been published by the Federal Aviation Administration . The operating instructions for pilots of Vickers Viscount machines have been revised, as have the corresponding maintenance instructions.
swell
- Robert J. Serling: Loud and Clear. Doubleday & Company Inc., Garden City (New York) 1969, pp. 225-235. (Library of Congress Catalog Card Number 68-22504.)
- Website unitedflight823.com
Individual evidence
- ↑ a b c d e f g h i j k l m Aircraft accident Vickers 745D Viscount N7405 Parrottsville, TN. Aviation Safety Network , accessed July 16, 2019 .
-
↑ Vickers Viscount production list. In: rzjets.net. Retrieved on August 23, 2019 (English, machine operating history). N7405. In: Federal Aviation Administration Licensing Register . Retrieved on August 23, 2019 (English, registration data set of the unlucky machine).
Coordinates: 36 ° 1 ′ 37 " N , 83 ° 3 ′ 41" W