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Contribution of Unstabilised Approaches to Aircraft Accidents and Incidents

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Article Information
Category: Toolkit for ATC - Stabilised Approach Stabilised Approach Awareness Toolkit for ATC
Content source: EUROCONTROL EUROCONTROL
Content control: EUROCONTROL EUROCONTROL

Description

The Flight Safety Foundation (FSF) established that unstabilised approaches were a causal factor in 66 % of 76 approach and landing accidents and incidents worldwide between 1984 and 1997.

It was found that many low and slow (low energy) approaches have resulted in controlled flight into terrain (Controlled Flight Into Terrain (CFIT)) because of inadequate vertical position awareness. Low energy approaches may also result in "loss-of-control" or "land-short" events.

High energy approaches have resulted in runway excursions and also have contributed to inadequate situational awareness in some of CFIT accidents.

It was found that a crew’s inability to control the aircraft to the desired flight parameters (airspeed, altitude, rate of descent) was a major factor in 45 % of 76 approach-and-landing accidents and serious incidents.

Flight-handling difficulties have occurred in situations which included rushing approaches, attempts to comply with demanding ATC clearances, adverse weather conditions and improper use of automation.

Consequences

Unstabilised approaches can be followed by:

  1. Runway excursions
  2. Landing short
  3. Controlled flight into terrain
  4. Hard landings
  5. Tail Strike

Contributory factors

Weather conditions or approach types which can increase the chances of an unstabilised approach are:

  1. wake turbulence
  2. strong winds
  3. low visibility
  4. heavy precipitation
  5. an approach with no visual references (e.g. night or Instrument Meteorological Conditions (IMC))
  6. visual approach
  7. circling approach

Aircraft Accidents and Incidents Related to Unstabilised Approach Listed on SKYbrary

  • B738, vicinity Kittilä, Finland 2012 (On 26 December 2012, a Boeing 737-800 experienced an uncommanded pitch up in IMC when intercepting the ILS GS at Kittilä. Initial crew response could not prevent a rapid transition to a very high nose up attitude and stick shaker activation occurred. Recovery from this upset was eventually achieved. The Investigation found that frozen de icing fluid had prevented three of the four input cranks for both elevator PCUs from functioning normally. It also concluded that, notwithstanding new de-icing procedures introduced by Boeing since the occurrence, the current aircraft type certification for all 737 variants may be unsound.)
  • A319, Rio de Janeiro Galeão Brazil, 2017 (On 19 July 2017, an Airbus A319 crew ignored the prescribed non-precision approach procedure for which they were cleared at Rio de Janeiro Galeão in favour of an unstabilised “dive and drive” technique in which descent was then continued for almost 200 feet below the applicable MDA and led to an EGPWS terrain proximity warning as a go around was finally commenced in IMC with a minimum recorded terrain clearance of 162 feet. The Investigation noted the comprehensive fight crew non-compliance with a series of applicable SOPs and an operational context which was conducive to this although not explicitly causal.)
  • B752, Puerto Plata Dominican Republic, 1998 (On 1 January 1998, a Boeing 757-200 being operated by Airtours International on a passenger charter flight from Bangor MA USA to Puerto Plata Dominican Republic struck the ground to the right of the intended landing runway shortly after the aircraft commander, flying manually as PF for a third approach, had initiated a late go around after failing to retain effective control of the aircraft. Despite sustaining substantial damage to the landing gear and airframe not appreciated by the flight crew, the aircraft was then successfully flown pressurised to the nominated diversion, Santo Domingo where an uneventful landing was accomplished. A fuel leak from the APU was observed once parked but the decision was taken to shut it down using the normal switch and not to expedite passenger disembarkation and no fire occurred. None of the occupants were injured during the landing attempt at Puerto Plata but the aircraft was found to have suffered extensive damage and had to be repaired before further flight by a team from the aircraft manufacturer.)
  • JS41, Rhodes Greece, 2015 (On 2 February 2015, a Jetstream 41 made a hard and extremely fast touchdown at Rhodes and the left main gear leg collapsed almost immediately. The crew were able to prevent the consequent veer left from leading to a lateral runway excursion. The Investigation found that the approach had been significantly unstable throughout with touchdown at around 50 knots above what it should have been and that a whole range of relevant procedures had been violated by the management pilot who had flown the approach in wind shear conditions in which approaches to Rhodes were explicitly not recommended.)
  • A320, vicinity Bahrain Airport, Kingdom of Bahrain, 2000 (On 23 August 2000, a Gulf Air Airbus A320 flew at speed into the sea during an intended dark night go around at Bahrain and all 143 occupants were killed. It was subsequently concluded that, although a number of factors created the scenario in which the accident could occur, the most plausible explanation for both the descent and the failure to recover from it was the focus on the airspeed indication at the expense of the ADI and the effect of somatogravic illusion on the recently promoted Captain which went unchallenged by his low-experience First Officer.)

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Stabilised Approach Awareness Toolkit for ATC

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Part of the Stabilised Approach Awareness Toolkit for ATC