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B772 / A321, London Heathrow UK, 2007

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Summary
On 27 July 2007, a British Airways Boeing 777-200ER collided, during pushback, with a stationary Airbus A321-200. The A321 was awaiting activation of the electronic Stand Entry Guidance (SEG) and expecting entry to its designated gate.
Event Details
When July 2007
Actual or Potential
Event Type
Ground Operations, Human Factors
Day/Night Day
Flight Conditions On Ground - Normal Visibility
Flight Details
Aircraft BOEING 777-200 / 777-200ER
Operator British Airways
Domicile United Kingdom
Type of Flight Public Transport (Passenger)
Intended Destination London Heathrow Airport
Take off Commenced No
Flight Airborne No
Flight Completed No
Flight Phase Pushback/towing
PBT
Flight Details
Aircraft AIRBUS A-321
Operator British Airways
Domicile United Kingdom
Type of Flight Public Transport (Passenger)
Intended Destination London Heathrow Airport
Take off Commenced Yes
Flight Airborne No
Flight Completed No
Flight Phase Standing
STD
Location - Airport
Airport London Heathrow Airport
General
Tag(s) Aircraft-aircraft collision
HF
Tag(s) Ineffective Monitoring,
Procedural non compliance
GND
Tag(s) Taxiway collision,
On gate collision,
Aircraft / Aircraft conflict,
Aircraft Push Back
Outcome
Damage or injury No
Aircraft damage Minor
Causal Factor Group(s)
Group(s) Aircraft Operation
Safety Recommendation(s)
Group(s) Aircraft Operation,
Airport Management
Investigation Type
Type Independent

Description

On 27 July 2007, a British Airways Boeing 777-200ER collided, during pushback, with a stationary Airbus A321-200. The A321 was awaiting activation of the electronic Stand Entry Guidance (SEG) and expecting entry to its designated gate.

Synopsis

This is an extract from the Bulletin 6/2009 concerning the accident (G-VIIK and G-EUXH) published by the Aircraft Accident Investigation Branch (AAIB), UK:

[…] As the Airbus approached its stand, the crew realised that the electronic Stand Entry Guidance (SEG) system was not switched on. This was because the operator’s ground staff responsible for activating it had not yet arrived at the stand. The Airbus commander stopped his aircraft about 50 metres short of the intended parking position; it was aligned with the stand centreline, but with about half the aircraft protruding into the taxiway behind. He made a radio call to GMC2 [Ground Movements Control 2], to advise that the stand guidance was not illuminated, but the frequency was very busy and the call was not acknowledged. Whilst the commander informed the passengers and cabin staff that the aircraft was not yet on stand, the co-pilot attempted to contact his company on discrete frequencies to request that ground crew attend the stand.

About a minute after the radio call from the Airbus to GMC2, the crew of the Boeing 777 called GMC2 to request pushback from Stand 429 (Figure 1), which the controller approved.

Figure 1. Layout of stands and taxiway in accident area (Source: AAIB Bulletin: 6/2009, Courtesy of Google Earth)


During pushback, the Boeing 777’s left wing collided with the Airbus’ fin. The tug driver reported that he had seen the Airbus moments earlier and had applied the vehicle’s brakes, but was too late to prevent the collision. (Figure 2)

Figure 2. Aircraft in proximity at about the time of the accident (Source: AAIB Bulletin: 6/2009, Courtesy of H. Ghattaoura)


The collision was felt on both aircraft. The Airbus crew made a further call to GMC2, stating that their aircraft had been struck, but it, too, was not acknowledged. They then twice broadcast a PAN-PAN call, which was acknowledged after the second broadcast. The Boeing 777 crew also made a PAN-PAN call. The GMC2 controller took the appropriate actions, and alerted the airport emergency services. The tug was equipped with a radio capable of receiving and making transmissions on the GMC2 frequency, but it was not switched on prior to, or during, the pushback.

The Airbus remained stationary after the collision, but the Boeing’s pushback crew immediately pulled the aircraft forward again, back onto Stand 429. […]

The Report presents the detailed account of the two member pushback crew: a tug driver and a headset operator. During the course of the investigation it became clear that, neglecting the company operating procedures, the headset operator did not walk alongside the aircraft during pushback. Instead he was in the tug when the pushback commenced and remained there for the duration of the pushback. A tangled headset line was stated by the headset operator to be the reason that he remained in the cab.

The Report points to the following conclusions regarding the accident (Analysis, page 70; see Further Reading):

The headset operator was required to be in a position to monitor the pushback area and the engine being started. These responsibilities were listed in the applicable publications and aide-memoires, and were principles which both crewmen had worked to for a number of years. Both would have known that to commence pushback with the headset operator still in the cab of the tug was not in accordance with their operating procedures.

If the headset operator had intended to leave the cab before pushback started, he could have done so. Since it was he who gave the tug driver the instruction to start the pushback, he could have delayed the instruction until the tangled headset lead had been dealt with. Similarly, he gave the commander clearance to start engines before the commander had requested it, which also indicates that the headset operator was content with his situation at that stage. He remained in the cab as the right engine was started, where his view of the engine was hindered by the seating arrangement and the aircraft structure, preventing him from adequately monitoring it, as he was required to do. The headset operator’s actions, and the lack of mention by the tug driver of any difficulty with the headset, would suggest that any problem with the headset lead was minor, and of limited impact. Therefore, it was not a contributory factor.

As the tug driver stated […], the view behind the aircraft from his position was very restricted, so he was dependent to a large extent upon the headset operator warning of obstacles or hazards that may not be visible to the driver. The driver would have been aware that the headset operator’s continued presence in the cab was contrary to procedures and would affect his ability to identify possible hazards. The driver had overall responsibility for the safety of the aircraft and ground crew during the pushback; he could have delayed or halted it at any time, but he did not.

It was a requirement of the airport authority and the aircraft operator that the tug’s radio be used to monitor the appropriate GMC frequency. As the radio was switched off, there was no possibility of the ground crew hearing any of the radio calls that could have alerted them to the developing situation.

Towing the Boeing 777 forward after the collision ran the risk of exacerbating the damage to both aircraft, and could potentially have hindered the accident investigation. Two experienced crewmen were involved, which highlights the need for a thorough grounding and regular recurrent training in accident and emergency procedures. The ATPM [Aircraft Towing and Pushback Manual] did not contain generic post-accident procedures and the lack of recurrent safety training meant that there was limited opportunity to review such procedures in a formal training environment.

According to the Report, the accident occurred primarily because the Boeing 777 pushback was not conducted in accordance with the aircraft operator’s normal operating procedures and safe practices. A number of organisational issues were also identified which may have been contributory. Five Safety Recommendations are made by AAIB UK (see Further Reading, AAIB Bulletin: 6/2009, pp 71-73).

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