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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 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 (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 IMC)
  6. visual approach
  7. circling approach

Aircraft Accidents and Incidents Related to Unstabilised Approach Listed on SKYbrary

  • CRJ2, Providence RI USA, 2007 (On 16 December 2007, a Bombardier CRJ-200 being operated by Air Wisconsin on a scheduled passenger flight from Philadelphia, PA to Providence RI made an ILS approach to Runway 05 at destination in IMC which became unstable but was continued to an extremely hard night touchdown which broke the left hand main landing gear and was followed by exit of the aircraft from the left hand side of the runway and a slide through a snow-covered grassy area before it came to a stop without impacting any obstructions. There were no injuries to the occupants, who left the aircraft using the integral air stairs at the main door but the aircraft suffered “substantial” damage.)
  • AT43, vicinity Stansted UK, 2007 (On 18 January 2007 an ATR 42-300 freighter developed a control difficulty just after a night take off from Stansted UK, which led the flight crew to declare an emergency and undertake an immediate return to land. The landing was uneventful but the approach flown was unstable, with EGPWS warnings, and the origin of the handling difficulty was considered to be, in part, due to inappropriate control inputs by one of the pilots.)
  • DH8A, vicinity Svolvær Norway, 2010 (On 2 December 2010, a DHC8-100 crew briefly lost control of their aircraft after encountering a microburst and came very close to both the sea surface and a stall when turning onto night visual final at Svolvær during an otherwise uneventful circling approach. After recovery from 83 feet agl, involving an unplanned change of control, an uneventful diversion to an alternate followed. Commencement of an investigation was delayed by failure to report the event at all initially, or fully. It was found that during loss of control, airspeed had dropped to 72 knots and rate of descent had exceeded 2,200 fpm.)
  • B744, Bangkok Thailand, 1999 (On 23 September 1999, a Boeing 747-400 being operated by Qantas on a scheduled passenger service from Sydney Australia to Bangkok overran Runway 21L during an attempted night landing in normal visibility and came to a halt substantially intact 320 metres beyond the runway end. There was no fire and a precautionary evacuation of the aircraft was not begun until 20 minutes after it came to rest. Only minor injuries were sustained by 38 of the 410 occupants, some during the initial runway excursion, others as a consequence of the evacuation. The aircraft remained substantially intact during the overrun although the nose landing gear and one main landing gear separated. The picture below, taken from the Official Accident Report, shows the aircraft in its final stopping position.)
  • B732, vicinity Islamabad Pakistan, 2012 (On 20 April 2012, the crew of a Boeing 737-200 encountered negative wind shear during an ILS final approach at night in lMC and failed to respond with the appropriate recovery actions. The aircraft impacted the ground approximately 4 nm from the threshold of the intended landing runway. The Investigation attributed the accident to the decision to continue to destination in the presence of adverse convective weather and generally ineffective flight deck management and noted that neither pilot had received training specific to the semi-automated variant of the 200 series 737 being flown and had no comparable prior experience.)
  • … further results


Stabilised Approach Awareness Toolkit for ATC

Further Reading

CANSO

Part of the Stabilised Approach Awareness Toolkit for ATC