If you wish to contribute or participate in the discussions about articles you are invited to join SKYbrary as a registered user

 Actions

Taxiway Collisions

From SKYbrary Wiki

Revision as of 00:20, 31 May 2018 by Editor2 (talk | contribs) (Prevention)
Article Information
Category: Ground Operations Ground Operations
Content source: SKYbrary About SKYbrary
Content control: SKYbrary About SKYbrary
Ambox content.png
The present article is under construction.
Reader enquiries are welcome, contact the editor: editor@skybrary.aero.
Ambox content.png

Description

An airport is a complex interface between the air and the ground environments, where access must be controlled and separation between aircraft or between aircraft and vehicular traffic must be maintained and optimised. While most occurrences on airport aprons and taxiways do not have consequences in terms of loss of life, they are often associated with aircraft damage, delays to passengers and avoidable financial costs.

This article examines collisions and near collisions whilst aircraft are on the airport manoeuvring areas inclusive of taxiways and ramp areas. The article On-Gate Collisions provides insight into aircraft collisions occurring whilst on, entering or leaving an assigned gate.

Occurrences

As previously stated, to ensure efficient and safe airport ground operations, separation between aircraft or between aircraft and vehicular traffic must be maintained and optimised. On occasion, however, minimum separation, particularly aircraft/vehicle separation is compromised. Whilst all events do not result in collision with an aircraft, the majority of taxiway occurrences involve vehicle operators deviating from a surface movement controller clearance. These "failure to comply" occurrences most usually involve vehicles:

  • using an incorrect taxiway
  • failing to stop at a taxiway holding point
  • failing to stay on the surface movement control radio frequency or ground frequency as appropriate
  • failing to obtain a clearance before entering an area subject to control.

In all cases, these actions have the potential to put the vehicle in conflict with an aircraft which, in turn, could:

  • lead to collision
  • require aggressive braking by the aircraft which could result in personnel injuries. Cabin crew are especially vulnerable as they might be moving within the cabin preforming pre-departure or post-landing duties


Most of the remaining occurrences are related to one of the following:

  • aircraft-aircraft collisions or near collisions - collisions can result from:
    • failure to follow taxiway centreline guidance
    • failure to stop prior to a stopbar
    • taxiing at speeds unsuited to the conditions or level of congestion
    • taxiway deviation whilst trying to manoeuvre to "squeeze" past another aircraft. Manoeuvring around an aircraft partially blocking a taxiway (as might be the case if the aircraft was approaching, but not yet at the stop point of, a gate) can lead to collision. If misjudged, this could result in a wingtip striking the tail of the stopped aircraft or it could compromise clearance between obstacles or other aircraft and the wingtip opposite the stopped aircraft
    • taxiway configuration - converging taxiways can potentially lead to reduced or compromised clearance, especially where they cross
  • reduced aircraft clearance with ground equipment or obstacles. Reduced clearance accidents or incidents can occur in various ways. These include:
    • inappropriate use of a restricted taxiway - some taxiways are restricted by wingspan. Use by a larger aircraft could compromise obstacle clearance
    • failure to follow taxi lane guidance - deviation from the lane guidance whilst manoeuvring in proximity to light stands, gates or stationary equipment can result in collision
  • jet blast -inappropriate thrust settings or following too closely can result in aircraft damage due to jet blast. Jet blast can also cause unsecured equipment such as Unit Load Devices (ULD) to move and strike other aircraft, equipment or personnel

Prevention

Most taxiway accidents and incidents are preventable. This prevention is dependant upon appropriate training and testing, compliance with clearances, published procedures and right-of-way rules, maintaining situational awareness and adapting speed of movement to suit the weather and surface conditions. Some specific accident prevention strategies are as follows:

  • Vehicle operators - It is imperative that vehicle operators be properly trained, tested and authorised for ramp and taxiway operations. Driving infractions should be investigated and additional training provided where appropriate. Multiple infractions should be considered grounds for suspension of airside driving privileges. Operators should:
    • ensure daily inspection for their vehicle is complete and that beacon/hazard lights are operating when the vehicle is airside
    • maintain situational awareness
    • operate their vehicle safely and in accordance with all company and airport rules
    • obey all "rules of the road" inclusive of speed limits, stop signs and right-of-way guidance
    • yield to aircraft at all times
    • obtain and read back any ground movement controller clearance prior to entering an area where clearance is required. If clearance is not understood, ASK!
  • Tug operators - Tug operators have the additional responsibility of moving aircraft on and off gates as well as positioning aircraft from one location on the airfield to another. In addition to the aforementioned items for vehicle operators, the tug operator must:
    • know the size of the aircraft in tow inclusive of the wingspan
    • be conversant with the normal taxi routes from one airfield location to another
    • understand the stopping distances required for a tug with an aircraft in tow
    • comply with all clearances, especially runway crossing clearances
    • use wing and tail walkers when manoeuvring in congested areas
  • Controllers - The ground controller is responsible for the safe and efficient movement of aircraft and vehicle traffic on the taxiways and aprons. They should:
    • provide the appropriate clearance for the requested action
    • ensure that the clearance readback is accurate
    • to the extent possible, monitor the movement visually, via transponder or by use of multilateration equipment to ensure clearance compliance
  • Pilots - In general, pilots are responsible for the ground movement of an aircraft from the runway to the gate and from the gate to the runway although they may also reposition aircraft from one point on the airfield to another. In all cases they should:
    • request, readback and comply with an appropriate clearance
    • maintain situational awareness
    • taxi at a speed appropriate to the conditions and traffic situation
    • maintain the centre of the taxi lane
    • be vigilant for taxi lane compromise by another aircraft, vehicle or object
    • not assume that vehicles will yield right-of-way

Accidents and Incidents

The following accidents and incidents involve collision or near collision between two aircraft, an aircraft and a vehicle, or an aircraft and a stationary object.

Aircraft/Aircraft Conflict

  • B738 / B738, Dublin Ireland, 2014 (On 7 October 2014, a locally-based Boeing 737-800 taxiing for departure from runway 34 at Dublin as cleared in normal night visibility collided with another 737-800 stationary in a queue awaiting departure from runway 28. Whilst accepting that pilots have sole responsible for collision avoidance, the Investigation found that relevant restrictions on taxi clearances were being routinely ignored by ATC. It also noted that visual judgement of wingtip clearance beyond 10 metres was problematic and that a subsequent very similar event at Dublin involving two 737-800s of the same Operator was the subject of a separate investigation.)
  • MD82 / MD11, Anchorage AK USA, 2002 (On 17 March 2002, at Ted Stevens Anchorage Airport, a McDonnell Douglas MD82 operated by Alaska Airlines, on a night pushback in snow conditions collided with an inbound taxiing McDonnell Douglas MD-11. The MD82 suffered substantial rudder damage although the impacting MD11 winglet was undamaged.)
  • B733 / DH8D, Fort McMurray Canada, 2014 (On 4 August 2014, a Boeing 737-300 making a day visual approach at Fort McMurray after receiving an ILS/DME clearance lined up on a recently-constructed parallel taxiway and its crew were only alerted to their error shortly before touchdown by the crew of a DHC8-400 which was taxiing along the same taxiway in the opposite direction. This resulted in a go around being commenced from 46 feet agl. The Investigation noted that both pilots had been looking out during the final stages of the approach and had ignored important SOPs including that for a mandatory go around from an unstable approach.)
  • FA7X, London City UK, 2016 (On 24 November 2016, a Dassault Falcon 7X being marshalled into an unmarked parking position after arriving at London City Airport was inadvertently directed into a collision with another crewed but stationary aircraft which sustained significant damage. The Investigation found that the apron involved had been congested and that the aircraft was being marshalled in accordance with airport procedures with wing walker assistance but a sharp corrective turn which created a 'wing growth' effect created a collision risk that was signalled at the last minute and incorrectly so by the wing walker involved and was also not seen by the marshaller.)
  • A321 / B734, Barcelona Spain, 2015 (On 25 November 2015, an Airbus A321 taxiing for departure at Barcelona was cleared across an active runway in front of an approaching Boeing 737 with landing clearance on the same runway by a Ground Controller unaware that the runway was active. On reaching the lit stop bar protecting the runway, the crew queried their clearance and were told to hold position. Noting that the event had occurred at the time of a routine twice-daily runway configuration change and two previous very similar events in 2012 and 2014, further safety recommendations on risk management of runway configuration change were made.)
  • DC91 / B722, Detroit MI USA, 1990 (On 3 December 1990 a Douglas DC9-10 flight crew taxiing for departure at Detroit in thick fog got lost and ended up stopped to one side of an active runway where, shortly after reporting their position, their aircraft was hit by a departing Boeing 727-200 and destroyed by the impact and subsequent fire. The Investigation concluded that the DC9 crew had failed to communicate positional uncertainty quickly enough but that their difficulties had been compounded by deficiencies in both the standard of air traffic service and airport surface markings, signage and lighting undetected by safety regulator oversight.)
  • DH8C / P180, Ottawa ON Canada, 2013 (On 1 December 2013, a small aircraft taxing for departure at night was cleared to cross an active runway and did so as a DHC8 was taking off from the same runway. Separation was significant and there was no actual risk of collision. The Investigation found that the GND controller had issued clearance to the taxiing aircraft when he had responsibility for its whole taxi route but had neither updated the aircraft status system nor directly advised of the taxiing aircraft when passing responsibility for part of its cleared route to the TWR controller who therefore remained unaware of it.)
  • B190 / B737, Calgary Canada, 2014 (On 29 March 2014, a Beech 1900D being taxied by maintenance personnel at Calgary entered the active runway without clearance in good visibility at night as a Boeing 737-700 was taking off. The 737 passed safely overhead. The Investigation found that the taxiing aircraft had taken a route completely contrary to the accepted clearance and that the engineer on control of the aircraft had not received any relevant training. Although the airport had ASDE in operation, a transponder code was not issued to the taxiing aircraft as required and stop bar crossing detection was not enabled at the time.)

Aircraft/Vehicle Conflict

  • E190 / Vehicle, Paris CDG France, 2014 (On 19 April 2014, an Embraer 190 collided with the tug which was attempting to begin a pull forward after departure pushback which, exceptionally for the terminal concerned, was prohibited for the gate involved. As a result, severe damage was caused to the lower fuselage. The Investigation found that the relevant instructions were properly documented but ignored when apron services requested a 'push-pull' to minimise departure delay for an adjacent aircraft. Previous similar events had occurred on the same gate and it was suspected that a lack of appreciation of the reasons why the manoeuvre used was prohibited may have been relevant.)
  • A343, Frankfurt Germany, 2008 (On 21 August 2008, an Airbus A340-300 being operated by an undisclosed operator by a German-licensed flight crew on a scheduled passenger flight from Teheran to Frankfurt collided with a stationary bus with only the driver on board whilst approaching the allocated parking gate in normal daylight visibility. The No 4 engine impacted the bus roof as shown in the photograph below reproduced from the official report. None of the occupants of either the aircraft or the bus were injured.)
  • Vehicle / PA31, Mackay SE Australia, 2008 (On 29 June 2012, a Piper PA31 taking off from runway 05 on a passenger charter flight just missed hitting an inspection vehicle which had entered the take off runway from an intersecting one contrary to ATC clearance. The overflying aircraft was estimated to have cleared the vehicle by approximately 20 feet and the pilot was unaware it had entered the active runway. The driver had been taking a mobile telephone call at the time and attributed the incursion to distraction. The breached clearance had been given and correctly read back approximately two minutes prior to the conflict occurring.)
  • B742, Stockholm Arlanda Sweden, 2007 (On 25 June 2007, a Boeing 747-200F being operated by Cathay Pacific on a scheduled cargo flight from Stockholm to Dubai had completed push back for departure in normal daylight visibility and the parking brakes had been set. The tow vehicle crew had disconnected the tow bar but before they and their vehicle had cleared the vicinity of the aircraft, it began to taxi and collided with the vehicle. The flight crew were unaware of this and continued taxiing for about 150 metres until the flight engineer noticed that the indications from one if the engines were abnormal and the aircraft was taxied back to the gate. The tow vehicle crew and the dispatcher had been able to run clear and were not injured physically injured although all three were identified as suffering minor injury (shock). The aircraft was “substantially damaged” and the tow vehicle was “damaged”.)
  • Vehicle / B752, Dublin Ireland, 2009 (On 29 May 2009, a Boeing 757-200 being operated by UK Airline Thomson Airways on a passenger charter flight from Sharm-el-Sheikh, Egypt to Dublin and having just landed on runway 10 at destination at night in poor visibility overtook a small ride-on grass mower moving along the right hand side of the runway in approximate line with the aircraft’s right hand wing tip. The driver of the mower was unaware of the arriving aircraft until he heard it on the runway behind him. Prior to the landing, ATC had been informed that all grass-cutting equipment previously working on and around the runway had cleared it.)
  • A320, London Heathrow UK, 2006 (On 26 June 2006, after an uneventful pre-flight pushback of a British Airways Airbus A320-200 at London Heathrow Airport, the aircraft started moving under its own power and, shortly afterwards, collided with the tractor that had just performed the pushback, damaging both the right engine and the tractor.)
  • ATP, Jersey Channel Islands, 1998 (On 9 May 1998, a British Regional Airlines ATP was being pushed back for departure at Jersey in daylight whilst the engines were being started when an excessive engine power setting applied by the flight crew led to the failure of the towbar connection and then to one of the aircraft's carbon fibre propellers striking the tug. A non standard emergency evacuation followed. All aircraft occupants and ground crew were uninjured.)
  • B738, London Stansted UK, 2008 (On 13 November 2008, a Boeing 737-800 with an unserviceable APU was being operated by Ryanair on a passenger flight at night was in collision with a tug after a cross-bleed engine start procedure was initiated prior to the completion of a complex aircraft pushback in rain. As the power was increased on the No 1 engine in preparation for the No 2 engine start, the resulting increase in thrust was greater than the counter-force provided by the tug and the aircraft started to move forwards. The towbar attachment failed and subsequently the aircraft’s No 1 engine impacted the side of the tug, prior to the aircraft brakes being applied.)

Aircraft/Object Conflict

  • B74S, Stockholm Arlanda Sweden, 1996 (On 14 June 1996, a Boeing 747SP being operated by Air China on a scheduled passenger flight from Beijing to Stockholm was arriving on the designated parking gate at destination in normal daylight visibility when it collided with the airbridge. None of the 130 occupants of the aircraft suffered any injury but the aircraft was “substantially damaged” and the airbridge was “damaged”.)
  • B738, Barcelona Spain, 2015 (On 12 December 2015, whilst a Boeing 737-800 was beginning disembarkation of passengers via an air bridge which had just been attached on arrival at Barcelona, the bridge malfunctioned, raising the aircraft nose gear approximately 2 metres off the ground. The door attached to the bridge then failed and the aircraft dropped abruptly. Prompt cabin crew intervention prevented all but two minor injuries. The Investigation found that the occurrence had been made possible by the failure to recognise new functional risks created by a programme of partial renovation being carried out on the air bridges at the Terminal involved.)
  • A346, Toulouse France, 2007 (During ground running of engines, the aircraft impacted a concrete wall at a ground speed of 30 kts following unintended movement and the aircraft was wrecked.)
  • AT72, Shannon Ireland, 2014 (On 26 February 2014, an ATR 72-202 which had been substituted for the ATR42 which usually operated a series of night cargo flights was being marshalled out of its parking position with a new flight crew on board when the left wing was in collision with the structure of an adjacent hangar. The Investigation found that the aircraft type had not been changed on the applicable flight plan and ATC were consequently unaware that the aircraft had previously been parked in a position only approved for the use by the usual smaller aircraft type.)
  • B734, Aberdeen UK, 2005 (Significant damage was caused to the tailplane and elevator of a Boeing 737-400 after the pavement beneath them broke up when take off thrust was applied for a standing start from the full length of the runway at Aberdeen. Although in this case neither outcome applied, the Investigation noted that control difficulties consequent upon such damage could lead to an overrun following a high speed rejected takeoff or to compromised flight path control airborne. Safety Recommendations on appropriate regulatory guidance for marking and construction of blast pads and on aircraft performance, rolling take offs and lead-on line marking were made.)
  • B738, Djalaluddin Indonesia, 2013 (On 6 August 2013, a Boeing 737-800 encountered cows ahead on the runway after landing normally in daylight following an uneventful approach and was unable to avoid colliding with them at high speed and as a result departed the runway to the left. Parts of the airport perimeter fencing were found to have been either missing or inadequately maintained for a significant period prior to the accident despite the existence of an airport bird and animal hazard management plan. Corrective action was taken following the accident.)
  • B722, Cotonou Benin, 2003 (On 25 December 2003, a Boeing 727-200 being operated by UTA (Guinea) on a scheduled passenger flight from Cotonou to Beirut with a planned stopover at Kufra, Libya, failed to get properly airborne in day VMC from the 2400 metre departure runway and hit a small building 2.45 metres high situated on the extended centreline 118 metres beyond the end of the runway. The right main landing gear broke off and ripped off a part of the trailing edge flaps on the right wing. The airplane then banked slightly to the right and crashed onto the beach where it broke into several pieces and ended up in the sea where the depth of water varied between three and ten metres. Of the estimated 163 occupants, 141 were killed and the remainder seriously injured.)
  • A319, Ibiza Spain, 2016 (On 19 June 2016, an Airbus A320 failed to follow the clearly-specified and ground-marked self-positioning exit from a regularly used gate at Ibiza and its right wing tip collided with the airbridge, damaging both it and the aircraft. The Investigation found that the crew had attempted the necessary left turn using the Operator’s ‘One Engine Taxi Departure’ procedure using the left engine but then failed to follow the marked taxi guideline by a significant margin. It was noted that there had been no other such difficulties with the same departure in the previous four years it had been in use.)

Related Articles

Further Reading

[[Category:Ground Operations [[Category:Operational Issues