TWA Flight 159

Infobox Airliner incident
name=TWA Flight 159
Crash

Date=November 6, 1967
Type=Takeoff abort with landing overshoot
Site=Erlanger, Kentucky
Fatalities=1
Injuries=10
Aircraft Type=Boeing 707
Operator=Trans World Airlines
Tail Number=N742TW
Passengers=29
Crew=7
Survivors =35 (28 passengers and 7 crew members)

On November 6, 1967, TWA Flight 159, a Boeing 707, while on its takeoff roll from Greater Cincinnati Airport, passed Delta Flight 379, a DC-9 stuck on the runway. The first officer on the TWA aircraft heard a loud bang, and, believing a collision had occurred, aborted the takeoff. The aircraft overran the runway, injuring 11 of the 29 passengers. One of the injured passenger died four days later as a result of the injuries. None of the seven crew members was injured.

Aircraft

The two aircraft involved were a Trans World Airline Boeing 707, tail number N742TW and (indirectly) a Delta Airlines DC-9, tail number N3317L.

Crash

TWA 159 had departed the terminal and while taxiing to runway 27L, DAL 379 was landing. The Delta crew requested permission to perform a 180 degree turnaround to vacate the runway at runway 18-36. During the turn the DC-9 was maneuvered off the runway, got the nose wheel stuck in the mud with the tail hanging about 7 feet off the edge of the runway. Air Traffic Control asked whether DAL 379 had left the runway, the crew replied "yeah, we're in the dirt though".

Subsequently ATC cleared TWA 159 for takeoff. The first officer was at the controls. During the takeoff run, and shortly after passing the stuck DAL 379 jet, a loud noise was heard and a yaw movement was felt in the controls. Believing he had hit the Delta aircraft and assuming he was below the decision speed V1, the first officer aborted the takeoff by closing the throttles, applying maximum brakes and calling for spoilers. The aircraft overran the runway to the brow of a hill, momentarily became airborne and contacted the ground 67 feet further, shearing the undercarriage, continued to slide down the embankment and came to rest an additional 421 feet from the runway end, near a roadway. The aircraft caught fire.

Aftermath

The National Transportation Safety Board conducted the investigation and it was revealed number 4 engine on TWA 159 had sustained a compressor stall as it passed the DC-9, due to jet blast. The stall was the sound of the "loud noise" heard in the cockpit. Thinking he was at or below V1, because the Captain had failed to announce V1, the First Officer aborted the takeoff. The probable cause for the accident was aborting the takeoff at a speed greater than what they could safely bring the aircraft to a stop on the runway. The contributing factor was the Delta crew had advised the tower that they were clear of the runway, without ascertaining the fact that they were not clear of the runway.

The NTSB also found that in aborting the takeoff, the TWA crew did not execute the abort properly. The TWA company manuals indicated aborting a takeoff at high speeds is dangerous, and should only be attempted if an actual engine failure occurs before V1 and stopping distance is limited. The manuals failed to consider the likelihood of other emergencies which would require an abort (V1 is important in regard to engine failure and not other emergencies). Due to the slowness of the abort the aircraft did not only overrun the runway but continued farther than it would have with a properly executed abort.

The TWA Boeing 707 was damaged beyond repair.

The Delta DC-9 cockpit voice recorder was recovered, but the bulk erase feature had been activated. The captain of DAL 379 testified this was done because of the profanity used when they became stuck. The NTSB was able to detect signals on the erased recorder and amplify them sufficiently to make them intelligible.

One NTSB member, Francis H. McAdams, concurred and dissented with the board, stating the probable cause of the accident was the Delta crew's failure to adequately advise the tower of the proximity to the runway, and the tower's failure to request additional and precise information prior to clearing TWA 159 for takeoff. He also noted that the tower had cleared the November 6, 1967 TWA Flight 128 to land even though it knew TWA 159 had aborted, which constituted a safety problem. In addition he recommended that based on the evidence in this case, based on the TWA Boeing 707 manual, and because on a balanced runway every foot of remaining runway is needed, an abort initiated at or below V1 may or may not be successful (uncertain outcome). He noted additional reaction time may be needed by pilots to decide whether other malfunctions (besides engine failure) should be considered when deciding between continuing takeoff or aborting.

References

* [http://amelia.db.erau.edu/reports/ntsb/aar/AAR68-AK.pdf NTSB Full accident report (1.2 Mb PDF)]
* [http://www.ntsb.gov/ntsb/brief.asp?ev_id=15733&key=0 NTSB accident brief CHI68A0043]
* [http://aviation-safety.net/database/record.php?id=19671106-0 Aviation Safety Network Database]
* [http://www.jetphotos.net/viewphoto.php?id=255692 Accident photo]