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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

  • A320, Khartoum Sudan, 2005 (On 11 March 2005, an Airbus A321-200 operated by British Mediterranean Airways, executed two unstable approaches below applicable minima in a dust storm to land in Khartoum Airport, Sudan. The crew were attempting a third approach when they received information from ATC that visibility was below the minimum required for the approach and they decided to divert to Port Sudan where the A320 landed without further incident.)
  • DH8A, Nuuk Greenland, 2011 (On 4 March 2011, an aircraft left the runway during a mishandled landing at Nuuk, Greenland which resulted in the collapse of the right main landing gear due to excessive 'g' loading. The landing followed an unstabilised VMC approach in challenging weather conditions. The Investigation concluded that the crew had become focussed solely on landing and that task saturation had mentally blocked any decision to go around. The aircraft commander had less than 50 hours experience on the aircraft type and had only been released from supervised line training 6 days earlier.)
  • JS31, Fort St. John BC Canada, 2007 (On 9 January 2007, a Peace Air British Aerospace Jetstream 31 on a scheduled service flight from Grand Prairie, Alberta made an instrument approach to Runway 29 at Fort St. John, British Columbia and touched down 320 feet short of the runway striking approach and runway threshold lights.)
  • LJ35, Lyon France, 2000 (On 2 May 2000, the crew of a LJ35 lost control of the aircraft, as a result of incorrect manual flying inputs, and crashed just before touchdown at Lyon, following an unstable single engine approach.)
  • 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.)
  • … further results


Stabilised Approach Awareness Toolkit for ATC

Further Reading

CANSO

Part of the Stabilised Approach Awareness Toolkit for ATC