The U.S. National Transportation Safety Board (NTSB) has dispatched a pair of investigators to Jackson Hole, Wyoming in response to an incident in which a United Airlines A320 aircraft veered off a runway after landing. The incident occurred on the evening of January 25, 2008 as the Airbus (registration number N442UA), arrived at Jackson Hole Airport (JAC) after a scheduled flight from Denver.In a press advisory announcing its investigation of the incident, the NTSB says that the aircraft, operating as United Airlines Flight UA 267, "departed the right side of runway 19 during landing at Jackson Hole Airport."
The airplane departed Denver at 7:44 pm MST with the intended destination of Jackson Hole. Visual meteorological conditions prevailed during the nighttime landing. The reported weather at the airport about the time of the incident was wind calm, visibility of 10 miles, and overcast clouds at 3200 feet above the ground.The six crew members and 119 passengers evacuated the aircraft using emergency slides. The NTSB noted that one of the emergency slides did not deploy. According to both the NTSB advisory and the FAA preliminary report about the incident, no injuries were reported, however local news media in Jackson Hole reported that a passenger had sustained a sprained wrist during the evacuation.
The airplane came to rest on its landing gear at about a 90 degree angle to the runway in snow about three feet deep. An initial examination of the aircraft revealed no readily visible signs of structural damage or evidence of fire.
An article about the incident in the Jackson Hole News & Guide pointed out that, "The incident is the fourth time an airplane has gone off the runway since December. Two weeks ago, a SkyWest CRJ700 was involved in a less serious mishap."
The Jackson Hole News & Guide article also includes comments about the incident from airport ground personnel, and quotes from passengers who were on board the flight.
The air traffic control tower at JAC was closed at the time of the accident. A news report quoted an airport official who said that first responders had to radio an incoming SkyWest flight to warn it not to land.
UPDATE - February 29, 2008: Today the NTSB released the following factual information from their ongoing investigation of the United Airlines A320 runway excursion at JAC, which occurred on February 25:
The airplane came to rest 116 feet past the end of the runway and 140 feet to the right of the runway centerline. A heavy skid mark was found on the runway associated with the inboard tire of the left main landing gear. This tire was found deflated and showed wear consistent with a skid. Upon exiting the runway, both engines ingested snow and sustained internal damage. The aircraft itself was not substantially damaged.The earlier incident mentioned by the NTSB was reported here on Aircrew Buzz in October.
Examination of the left main landing gear brakes revealed that the inboard and outboard wheel speed tachometer wires were cross-connected. Such a configuration would be likely to cause the antiskid system to use the inboard wheel speed to control the outboard braking, and vice versa. In such a situation, it would be likely that when the inboard tire began to skid, the antiskid system would release the pressure on the outboard brake instead of the inboard brake.
Examination of maintenance records indicated that both main landing gear units were replaced on the incident airplane in early February 2008. The Safety Board is also investigating another United A-320 incident with similar circumstances that occurred on October 9, 2007.
