B737 / A332, Seatle-Tacoma WA USA, 2008
B737 / A332, Seatle-Tacoma WA USA, 2008
Summary
On 2 July 2008, an Air Tran Airways B737-700 which had just landed at night on runway 34C at Sea-Tac failed to hold clear of runway 34R during taxi as instructed and passed almost directly underneath a North West Airlines A330-200 which had just become airborne from Runway 32R. The Investigation found that the 737 crew had been unaware of their incursion and that the alert provided by ASDE-X had not provided an opportunity for ATC to usefully intervene to stop prevent the potential conflict
Flight Details
Aircraft
Operator
Type of Flight
Public Transport (Passenger)
Intended Destination
Take-off Commenced
Yes
Flight Airborne
Yes
Flight Completed
Yes
Phase of Flight
Taxi
Flight Details
Aircraft
Operator
Type of Flight
Public Transport (Passenger)
Flight Origin
Intended Destination
Take-off Commenced
Yes
Flight Airborne
Yes
Flight Completed
Yes
Phase of Flight
Take Off
Location
Location - Airport
Airport
General
Tag(s)
Aircraft-aircraft near miss
HF
Tag(s)
Distraction,
Ineffective Monitoring,
Procedural non compliance
RI
Tag(s)
Accepted ATC Clearance not followed,
Incursion after Landing,
Runway Crossing,
Intersecting Runways,
Near Miss
Outcome
Damage or injury
Yes
Non-aircraft damage
Yes
Non-occupant Casualties
No
Off Airport Landing
Yes
Ditching
Yes
Causal Factor Group(s)
Group(s)
Aircraft Operation
Safety Recommendation(s)
Group(s)
None Made
Investigation Type
Type
Independent
Description
On 2 July 2008, a Boeing 737-700 being operated by Air Tran Airways on domestic scheduled passenger flight from Baltimore to Seattle-Tacoma had, in normal ground visibility at night, failed to hold clear of runway 34R during taxi in after landing on runway 34C at destination and had passed almost directly underneath a North West Airlines Airbus 330-200 which had just become airborne on a flight to London Heathrow.
Investigation
An Investigation was carried out by the National Transportation Safety Board (USA) (NTSB). It was found that the A330 had been in compliance with a valid take off clearance and that the 737 had been in breach of its taxi in clearance.
It was established that having landed on runway 34L and taken Rapid Exit Taxiway ‘F’, the 737, with the First Officer as PF, had then failed to hold short of runway 34 as instructed and was crossing the runway as the A330 passed almost directly overhead after it had become airborne on runway 34R between taxiways M and N with an estimated vertical clearance of just over 400 feet between the two aircraft. It was noted that the hold short clearance had been acknowledged twice but that the 737 crew claimed that they had not seen the illuminated hold short line prior to the incursion. They also stated that they had not heard the 330 being given take off clearance on the same frequency.
The 330 flight crew subsequently advised that they had not seen the 737 and had been unaware of the incursion.
It was note that taxiway F had enhanced hold short lines that were 77 metres from the Runway 34R left hand edge markings and that taxiway F had a lit centreline and elevated runway guard lights at the holding point concerned.
It was noted that Airport Surface Detection Equipment, Model X (ASDE-X) had been activated as the incursion occurred with both an aural and visual alert but no useful response had been available to the TWR controller.
The Investigation concluded that the Probable Cause of the conflict was “the diverted attention during taxi of the flight crew in the (Boeing 737)” and that contributing to the incident was the fact that the 737 had not followed its air traffic control clearance.
The Final Report of the Investigation was adopted on 26 September 2008. No Safety Recommendations were made.
