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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

  • A320, vicinity Oslo Norway, 2008 (On 19 December 2008, an Aeroflot Airbus A320 descended significantly below its cleared and acknowledged altitude after the crew lost situational awareness at night whilst attempting to establish on the ILS at Oslo from an extreme intercept track after a late runway change and an unchallenged incorrect readback. The Investigation concluded that the response to the EGPWS warning which resulted had been “late and slow” but that the risk of CFIT was “present but not imminent”. The context for the event was considered to have been poor communications between ATC and the aircraft in respect of changes of landing runway.)
  • DH8D, London Gatwick UK, 2009 (On 1 November 2009, a Bombardier DHC8-400 by Flybe, made a hard landing at London Gatwick due abnormal high pitch angle and significant structural damage to the aft lower airframe resulted.)
  • SW4, Sanikiluaq Nunavut Canada, 2012 (On 22 December 2012, the crew of a Swearingen SA227 attempting a landing, following an unstabilised non-precision approach at Sanikiluaq at night with questionable alternate availability in marginal weather conditions, ignored GPWS PULL UP Warnings, then failed in their attempt to transition into a low go around and the aircraft crashed into terrain beyond the runway. One occupant – an unrestrained infant – was killed and the aircraft was destroyed. The Investigation faulted crew performance, the operator and the regulator and reiterated that lap-held infants were vulnerable in crash impacts.)
  • A306, vicinity Birmingham AL USA, 2013 (On 14 August 2013, a UPS Airbus A300-600 crashed short of the runway at Birmingham Alabama on a night IMC non-precision approach after the crew failed to go around at 1000ft aal when unstabilised and then continued descent below MDA until terrain impact. The Investigation attributed the accident to the individually poor performance of both pilots, to performance deficiencies previously-exhibited in recurrent training by the Captain and to the First Officer's failure to call in fatigued and unfit to fly after mis-managing her off duty time. A Video was produced by NTSB to further highlight human factors aspects.)
  • MA60, Kupang Indonesia, 2013 (On 10 June 2013, a Merpati Nusantara Xian MA60 flown by a First Officer undergoing supervised line training made an unstable visual approach at destination which culminated in a sudden further increase in the rate of descent. The aircraft initially touched down on the runway with a vertical acceleration of 6g and then, after a bounce of -3g, stopped in 200 metres. The impact resulted in the wing box separating from the fuselage. The Investigation found that the Power Levers had been unintentionally moved into the ground range shortly before touchdown without either pilot being aware.)

... further results


Stabilised Approach Awareness Toolkit for ATC

Further Reading

CANSO

Part of the Stabilised Approach Awareness Toolkit for ATC