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B738 / B738, Toronto Canada, 2018

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Summary
On 5 January 2018, an out of service Boeing 737-800 was pushed back at night into collision with an in-service Boeing 737-800 waiting on the taxiway for a marshaller to arrive and direct it onto the adjacent terminal gate. The first aircraft’s tail collided with the second aircraft’s right wing and a fire started. The evacuation of the second aircraft was delayed by non-availability of cabin emergency lighting. The Investigation attributed the collision to failure of the apron controller and pushback crew to follow documented procedures or take reasonable care to ensure that it was safe to begin the pushback.
Event Details
When January 2018
Actual or Potential
Event Type
Fire Smoke and Fumes, Ground Operations, Human Factors
Day/Night Night
Flight Conditions On Ground - Normal Visibility
Flight Details
Aircraft BOEING 737-800
Operator WestJet
Domicile Canada
Type of Flight Public Transport (Passenger)
Origin Cancún International Airport
Intended Destination Toronto/Lester B. Pearson International Airport
Take off Commenced Yes
Flight Airborne Yes
Flight Completed Yes
Flight Phase Standing
STD
Flight Details
Aircraft BOEING 737-800
Operator Sunwing
Domicile Canada
Type of Flight Out of Service
Flight Phase Pushback/towing
PBT
Location - Airport
Airport Toronto/Lester B. Pearson International Airport
General
Tag(s) Aircraft-aircraft collision
AGC
Tag(s) Phraseology
FIRE
Tag(s) Post Crash Fire,
Fire-Wing
HF
Tag(s) Procedural non compliance
GND
Tag(s) On gate collision,
Aircraft / Aircraft conflict,
Aircraft Push Back,
No Flight Crew on Board
EPR
Tag(s) MAYDAY declaration,
Cabin Baggage Issues
CS
Tag(s) Evacuation on Pax Initiative
Outcome
Damage or injury Yes
Aircraft damage Minor
Injuries Few occupants
Causal Factor Group(s)
Group(s) Aircraft Operation,
Airport Operation
Safety Recommendation(s)
Group(s) None Made
Investigation Type
Type Independent

Description

On 5 January 2018, a Boeing 737-800, (C-FDMB) being operated by WestJet on a scheduled international passenger flight from Cancun, Mexico to Toronto as WJA2425 was stationary with engines running abeam the assigned gate at destination awaiting the ground personnel needed to marshall it onto its assigned arrival gate in normal night visibility when an out of service Sunwing Airlines Boeing 737-800 was pushed back and its tail collided with the right side wing of the WestJet aircraft. Fire broke out in both aircraft and a MAYDAY was declared by the WestJet crew and an emergency evacuation of their 169 passengers was carried out with no reported injuries. The Sunwing aircraft was detached from the impact position and towed away from it and the fires affecting both aircraft were extinguished without creating any direct personal hazard. The only recorded injury during the evacuation was a minor one to a member of the cabin crew.

Investigation

A “limited-scope, fact-gathering” Investigation was carried out by the Canadian Transportation Safety Board (TSB). It was noted that the inbound WestJet aircraft had been waiting for marshalling onto its assigned gate B12 at Terminal 3 and had been stationary and facing north east on Taxi Lane 2 just short of the gate turn on. This placed it behind the Sunwing aircraft parked nose-in and out of service on gate B13. The Sunwing aircraft had a technician employed by the aircraft operator on the flight deck and its APU was running. Two Swissport employees were in the cab of a tug attached to the nose of the aircraft and preparations were being made to push the aircraft back prior to repositioning.

The area where the collision occurred. [An extract reproduced from the Canada AIP Toronto Terminal 3 Parking Areas Chart]

What Happened

Sixteen minutes after the WestJet aircraft had stopped, it was still waiting for a marshaller when the other 737’s tug crew called ‘APRON NORTH’ for clearance to push and were told they could “push back at your discretion”. The push was then commenced without wing walkers and without awareness of the aircraft behind. Soon afterwards, the tail of the aircraft being pushed back hit the right wing of the WestJet 737 and the latter’s crew advised ‘APRON NORTH’ of the collision and they in turn instructed the tug crew to pull their aircraft back onto gate B13.

Thirty seconds after the impact had occurred, “a large ball of fire erupted near the area of aircraft contact”. The WestJet flight crew were immediately aware of the fire and began the evacuation quick reference checklist, declared a MAYDAY and advised that an evacuation was commencing. The ARFF were notified accordingly. The Sunwing technician shut down the APU and discharged the APU fire extinguisher before exiting the flight deck via the left side window and the emergency rope, sustaining minor injuries as he did so. Once the Sunwing aircraft had been pulled clear, the fire on the wing of the WestJet aircraft self-extinguished, but the fire at the tail of the Sunwing aircraft continued, although with less intensity.

Meanwhile, when the fire erupted, some of the WestJet passengers panicked and “three seconds after the fire erupted, and before any commands from the crew, passengers seated at the forward left over-wing emergency exit opened the exit and escaped onto the wing; other passengers followed". At this point, the engines were still running. Two members of cabin crew seated at the rear of the aircraft saw the fire and, having seen that some passengers were panicking, decided that an immediate evacuation should be commenced. They judged that it was not safe to use the rear right door and called the Captain and lead cabin crew by interphone to report the fire and advise that that they were evacuating via the rear left rear.

The two members of cabin crew at the front of the aircraft did not immediately begin to evacuate because they were waiting for a command to do so from the flight deck. The lead cabin crew also reported being aware that as the engine were still running, opening the front doors would put the passengers at risk. The flight crew ran the evacuation checklist but the engine and APU fire switches were not pulled because the First Officer “deemed this action not relevant to the current situation”. The unappreciated consequence of this was that neither the internal nor the external emergency lights were automatically activated.

Forty-nine seconds after the fire had begun, the Captain made a PA ordering an emergency evacuation. Both front doors were opened and in accordance with Company SOP, the First Officer then left the aircraft to assist the passengers. It was reported that although cabin crew made calls with and without the assistance of a handheld megaphone instructing passengers to leave their carry-on baggage behind, many still brought it with them which slowed down the evacuation. Also, some passengers who used the two left over wing exits re-entered the aircraft after failing to see either a slide or the (in the absence of illuminated external emergency lights) the arrows showing the exit route to and down the extended trailing edge flaps.

When the Captain emerged from the flight deck and noticed that the emergency lights were not illuminated, he went back into it, noticed that the APU was still running and shut it down after which the emergency lights activated.

It was found that from the time the Captain ordered an evacuation, it took almost 2½ minutes to complete and from the time the left over wing exit was opened, almost 3½ minutes. Once outside, the evacuated passengers moved away from the aircraft towards A4 gate on the other side of the two Taxi Lanes. All occupants had left the aircraft by the time the ARFF arrived and the fire in the Sunwing aircraft’s tail and APU had subsided but was still smouldering. As the remnants of the fire were extinguished, one of the fire crew sustained “minor injuries from exposure to secondary spray of water that was mixed with fuel from the APU”.

Review

The Investigation looked at a number of aspects related to the event as follows:

  • The APRON NORTH radio frequency is not manned by licensed air traffic controllers but by radio officers employed by the Airport Operator’s ‘Apron Management Unit’ (AMU). Their instructions therefore have the status of an “advisory traffic service”. They are located in a tower in Terminal 1 and have their own SOPs. They do not have a clear view of several parts of the manoeuvring area they look after, including that where the collision occurred but they do have access to multiple live video feeds and access to ASDE to make up for this. Recorded video camera and ASDE data for the time leading up to the collision were examined and these clearly showed the WestJet aircraft parked behind the Sunwing aircraft and a radar target displayed directly behind the Sunwing aircraft respectively. The AMU SOPs require that pushback information must include considerably more detail than simply “pushback at your discretion” including (but not limited to) which lane the pushback is to be made into and which way the aircraft should face on completion.
  • The AMU SOPs were found to say, in respect of aircraft under tow, that the (aircraft) operator “shall ensure operational safety through the use of wing walkers or other industry accepted best practice”. Sunwing, the aircraft operator in this case, was found to have ground-handling procedures which required wing walkers for all pushbacks, whether or not the aircraft has passengers on board. It was noted that when Sunwing conducted a ground operations station audit at Toronto in 2016, it found that wing walkers were used for the observed aircraft’s arrival and pushback but whether passengers were on board was not recorded.
  • It was found during the Investigation that “the general practice at Swissport (the ground handling contractor involved) was to have wing walkers present for pushbacks only when aircraft have passengers on board”. Despite this, Swissport SOPs for pushbacks were found to state that “a minimum of two wingwalkers as applicable and a pushback operator is required to conduct an aircraft movement.”
  • The WestJet passenger safety briefing card was found to include a graphic illustration indicating that passengers must not take personal belongings with them in the event of an evacuation. The actual content of the pre-flight safety briefing given prior to the investigated flight “could not be determined” but it was noted that the “sample pre-flight safety briefings” included in WestJet’s Cabin Crew Manual did not include any reference to this subject. The passenger safety briefings on a randomly-selected small number of scheduled flights on different Canadian airlines were observed by TSB Investigators to see whether passengers were being provided with instructions to leave baggage behind in the event of an emergency evacuation. None of the briefings on these flights included any such instruction to the passengers. Transport Canada’s intentions in this matter were noted.
  • WestJet cabin crew procedures require that if any member has initiated an evacuation, the other cabin crew should also do so, not await instruction from the flight crew before doing so.
  • One of the bases for type certification of the Boeing 737-800 was the demonstration that an emergency evacuation of a fully loaded aircraft could be carried out within 90 seconds - much less than was achieved in the investigated event.

The Conclusions of the Investigation were summarised as follows:

  • The pushback was conducted without the use of wing walkers, which is not in accordance with Swissport, Sunwing or Airport Authority requirements.
  • Wing walkers were normally used by Swissport only when pushing back aircraft with passengers on board.
  • The R/T phraseology used by the Apron Radio Officer was not consistent with the procedures of the Airport Authority Apron Management Unit (AMU).
  • WestJet’s pre-flight safety briefings do not inform passengers to leave behind carry-on baggage in the event of an evacuation and several passengers retrieved their carry-on baggage, despite the fact that cabin crew repeatedly provided specific instructions to the contrary. These passenger actions and the lack of aircraft emergency lighting, delayed the evacuation process.

The Final Report of the Investigation was authorised for release on 4 July 2018 and it was officially released on 11 July 2018. No Safety Recommendations were made.

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