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B752 / CRJ7, San Francisco CA USA, 2008 (GND HF)
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| Summary | |
| On 13 January 2008, a Boeing 757-200 and a Bombardier CL-600 received pushback clearance from two adjacent terminal gates within 41 seconds. The ground controller believed there was room for both aircraft to pushback. During the procedure both aircraft were damaged as their tails collided. The pushback procedure of the Boeing was performed without wing-walkers or tail-walkers. | |
 | |
| Event Details | |
|---|---|
| When | January 2008 |
| Event Type | GND, HF |
| Day/Night | Night |
| Flight Conditions | On Ground - Normal Visibility |
| Flight Details | |
|---|---|
| Aircraft | BOEING 757-200 |
| Operator | United Airlines |
| Domicile | United States |
| Type of Flight | |
| Origin | San Francisco |
| Flight Phase | Pushback/towing |
| PBT | |
| Flight Details | |
|---|---|
| Aircraft | CANADAIR Regional Jet CRJ-700 |
| Operator | SkyWest |
| Domicile | United States |
| Type of Flight | Public Transport (Passenger) |
| Origin | San Francisco |
| Intended Destination | Boise |
| Flight Phase | Pushback/towing |
| PBT | |
| Location - Airport | |
|---|---|
| Airport | San Francisco |
| General | |
|---|---|
| Tag(s) | Aircraft-aircraft collision Inadequate Aircraft Operator Procedures |
| HF | |
|---|---|
| Tag(s) | Ineffective Monitoring Violation Procedural non compliance ATC clearance error |
| GND | |
|---|---|
| Tag(s) | On gate collision Aircraft / Aircraft conflict ATC clearance error Aircraft Push Back |
| Outcome | |
|---|---|
| Damage or injury | No |
| Aircraft damage | Major |
| Injuries | Nonewarning.png"None" is not in the list of possible values (Few occupants, Many occupants, Most or all occupants) for this property. |
| Fatalities | Nonewarning.png"None" is not in the list of possible values (Few occupants, Many occupants, Most or all occupants) for this property. |
| Causal Factor Group(s) | |
|---|---|
| Group(s) | Aircraft Operation Air Traffic Management |
| Safety Recommendation(s) | |
|---|---|
| Group(s) | None Made |
| Investigation Type | |
|---|---|
| Type | Independent |
Contents |
Description
On 13 January 2008, an out of service United Airlines Boeing 757-200 and a Bombardier CRJ-700 being operated by Sky West on a United Express scheduled passenger service from San Francisco to Boise ID received pushback clearance from two adjacent terminal gates in quick sucession. Both aircraft were subsequiently damaged as their tails collided in onditions of normal night visibility. The CRJ sustained damage to vertical stabiliser, rudder and elevator and the Boeing sustained damage to rudder and elevator. None of the 60 occupants of the two aircraft or any ground personnel were injured.
Investgation
An Investigation was carried out by the NTSB. It was noted that the pushback of the Boeing was performed without wing-walkers or tail-walkers. The flight crew of the CRJ700 reported that during the final stages of pushback from gate 79, they were in a stopped position with both engines running while their ground crew was in the process of disconnecting the tug when the collision occurred. Company maintenance personnel stated they were pushing the 757 back from gate 80 without the use of wing-walkers or tail walkers to relocate the airplane to another location on the airport and did not see the CRJ. A review of ATC GND tapes showed that the 757 had initially been cleared for pushback onto taxiway Alpha from gate 80. About 40 seconds later, the ground controller had also cleared the CRJ to push back onto taxiway Alpha from gate 79. The recordings showed that the ground controller did not advise either aircraft of near simultaneous adjacent pushback operations. The controller stated that he believed there was room for both aircraft to push back and did not foresee a traffic conflict.
Probable Cause
The NTSB determined that the Probable Cause of this accident as:
- The company tug operator's failure to maintain clearance (of the Boeing from the CRJ)during the pushback process.
It was also considered that the ground controller's failure to alert the pilot of the CRJ and the tug operator of that aircraft to the simultaneous pushback occurring from adjacent gate was causal and that "contributing to the accident was the Boeing's pushback operation without the use of wing/tail walkers."
No Safety Recommendations were made as a result of this Investigation.