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**inappropriate use of a restricted taxiway - some taxiways are restricted by wingspan. Use by a larger aircraft could compromise obstacle clearance
 
**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
 
**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 ULDs to move and strike other aircraft, equipment or personnel
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*jet blast -inappropriate thrust settings or following too closely can result in aircraft damage due to [[Jet Efflux Hazard|jet blast]]. Jet blast can also cause unsecured equipment such as [[Unit Load Devices]] to move and strike other aircraft, equipment or personnel
  
 
==Prevention==
 
==Prevention==

Revision as of 15:00, 29 May 2018

Article Information
Category: Ground Operations Ground Operations
Content source: SKYbrary About SKYbrary
Content control: SKYbrary About SKYbrary
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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 stop bar
    • 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

Accidents and Incidents

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

Aircraft/Aircraft Conflict

  • A319 / UNKN, Stockholm Arlanda Sweden, 2011 (On 5 February 2011, an Airbus A319-100 being operated by Air Berlin on a passenger flight departing Stockholm inadvertently proceeded beyond the given clearance limit for runway 19R and although it subsequently stopped before runway entry had occurred, it was by then closer to high speed departing traffic than it should have been. There was no abrupt stop and none of the 103 occupants were injured.)
  • B763 / A320, Delhi India, 2017 (On 8 August 2017, a Boeing 767-300 departing Delhi was pushed back into a stationary and out of service Airbus A320 on the adjacent gate rendering both aircraft unfit for flight. The Investigation found that the A320 had been instructed to park on a stand that was supposed to be blocked, a procedural requirement if the adjacent stand is to be used by a wide body aircraft and although this error had been detected by the stand allocation system, the alert was not noticed, in part due to inappropriate configuration. It was also found that the pushback was commenced without wing walkers.)
  • 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.)
  • 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.)
  • DH8D / B737, Winnipeg Canada, 2014 (On 4 August 2014, the crew of a DHC8-400 departing Winnipeg continued beyond the holding point to which they had been cleared to taxi as a B737 was about to land. ATC observed the daylight incursion visually and instructed the approaching aircraft to go around as the DHC8 stopped within the runway protected area but clear of the actual runway. The Investigation found that the surface marking of the holding point which had been crossed was "significantly degraded" and noted the daily airport inspections had failed to identify this.)
  • B738/B763, Barcelona Spain, 2011 (On 14 April 2011, a Ryanair Boeing 737-800 failed to leave sufficient clearance when taxiing behind a stationary Boeing 767-300 at Barcelona and the 737 wingtip was in collision with the horizontal stabiliser of the 767, damaging both. The 767 crew were completely unaware of any impact but the 737 crew realised the ‘close proximity’ but dismissed a cabin crew report that a passenger had observed a collision. Both aircraft completed their intended flights without incident after which the damage was discovered, that to the 767 requiring that the aircraft be repaired before further flight.)
  • B738/B738, Girona Spain, 2010 (On 14 January 2010, two Ryanair Boeing 737-800 aircraft were operating scheduled passenger flights from Girona to Las Palmas and Turin respectively and had taxied from adjacent gates at Girona in normal day visibility in quick succession. The Turin-bound aircraft taxied first but because it was early at the holding point for its CTOT, the other aircraft was designated first for take off and during the overtaking manoeuvre in the holding area, the wing tip of the moving Las Palmas aircraft hit the horizontal stabiliser of the Turin bound aircraft causing minor and substantial damage to the respective aircraft. None of the respective 81 and 77 occupants were injured and both aircraft taxied back to their gates.)
  • 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.)

Aircraft/Vehicle Conflict

  • 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.)
  • 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, Dublin Ireland, 2017 (On 27 September 2017, an Airbus A320 being manoeuvred off the departure gate at Dublin by tug was being pulled forward when the tow bar shear pin broke and the tug driver lost control. The tug then collided with the right engine causing significant damage. The tug driver and assisting ground crew were not injured. The Investigation concluded that although the shear pin failure was not attributable to any particular cause, the relative severity of the outcome was probably increased by the wet surface, a forward slope on the ramp and fact that an engine start was in progress.)
  • Vehicle / E190 / E121, Jersey Channel Islands, 2010 (On 1 June 2010, an Airport RFFS bird scaring vehicle entered the active runway at Jersey in LVP without clearance and remained there for approximately three minutes until ATC became aware. The subsequent Investigation found that the incursion had fortuitously occurred just after an ERJ 190 had landed and had been terminated just as another aircraft had commenced a go around after failure to acquire the prescribed visual reference required to continue to a landing. The context for the failure of the vehicle driver to follow existing procedures was found to be their inadequacy and appropriate changes were implemented.)
  • B744, Paris CDG France, 2003 (On 18 January 2003, a Boeing 747-400F being operated by Singapore Airlines Cargo on a scheduled cargo flight from Paris CDG to Dubai taxied for departure in darkness and fog with visibility less than 100 metres in places and the right wing was in collision with a stationary and unoccupied ground de/anti icing vehicle without the awareness of either the flight crew or anybody else at the time. Significant damage occurred to the de icing vehicle and the aircraft was slightly damaged. The vehicle damage was not discovered until almost two hours later and the aircraft involved was not identified until it arrived in Dubai where the damage was observed and the authorities at Paris CDG advised.)
  • B763, Luton UK, 2005 (On 16 February 2005, at Luton Airport, a Boeing B767-300 collided with the tug pulling it forward when the shear pin of the unserviceable tow bar being used to pull the aircraft broke. The aircraft ran onto the tug when the ground crew stopped the tug suddenly. As result of the collision with the tug the aircraft fuselage and landing gear was damaged.)
  • 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.)
  • SB20, Stockholm Arlanda, 2001 (On 18 December 2001, a Saab 2000 being operated by Air Botnia on scheduled passenger flight from Stockholm to Oulu was taxiing out at night in normal visibility in accordance with its ATC clearance when a car appeared from the left on a roadway and drove at speed on a collision course with the aircraft. In order to avoid a collision, the aircraft had to brake sharply and the aircraft commander saw the car pass under the nose of the aircraft and judged the vehicle’s closest distance to the aircraft to be four to five metres. The car did not stop, could not subsequently be identified and no report was made by the driver or other witnesses. The diagram below taken from the official report shows the site of the conflict - the aircraft was emerging from Ramp ‘G’ to turn left on taxiway ‘Z’ and the broken line shows the roadway which is crossed just before the left turn is commenced.)

Aircraft/Object Conflict

  • 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.)
  • 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.)
  • B737, Amsterdam Netherlands, 2003 (n 22 December 2003, a Boeing 737-700 being operated by UK Operator Easyjet on a scheduled passenger flight from Amsterdam to London Gatwick was taxiing for departure at night in normal visibility and took a different route to that instructed by ATC. The alternative route was, unknown to the flight crew, covered with ice and as a consequence, an attempt to maintain directional control during a turn was unsuccessful and the aircraft left wing collided with a lamp-post. The collision seriously damaged the aircraft and the lamp post. One passenger sustained slight injuries because of the impact. The diagram below taken from the official investigation report shows the area where the collision occurred.)
  • 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.)
  • RJ85, Helsinki Finland 2010 (On 12 June 2010, a requested 22R runway inspection at Helsinki in normal daylight visibility carried out after a severe engine failure during the take off roll had led an Avro RJ85 being operated by Finnish Airline Blue1 on a scheduled passenger flight to Copenhagen to reject that take off at high speed. This inspection had not detected significant debris deposited on the runway during the sudden and severe engine failure. Two passenger aircraft, one being operated by Finnair to Dubrovnik, Croatia and the other being operated by Swedish airline TUIfly Nordic to Rhodes, Greece then departed the same runway before a re-inspection disclosed the debris and it was removed. Neither of the aircraft which used the runway prior to debris removal were subsequently found to have suffered any damage but both were advised of the situation en route.)
  • A342, Perth Australia, 2005 (On 24 April 2005, an Airbus A340-200 landed short of the temporarily displaced runway threshold at Perth in good daylight visibility despite their prior awareness that there was such a displacement. The Investigation concluded that the crew had failed to correctly identify the applicable threshold markings because the markings provided were insufficiently clear to them and probably also because of the inappropriately low intensity setting of the temporary PAPI. No other Serious Incidents were reported during the same period of runway works.)
  • 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.)

Related Articles

Further Reading

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