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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

  • A319, vicinity Zurich Switzerland, 2014 (On 17 October 2014, two recently type-qualified Airbus A319 pilots responded in a disorganised way after a sudden malfunction soon after take-off from Zurich required one engine to be shutdown. The return to land was flown manually and visually at an excessive airspeed and rate of descent with idle thrust on the remaining engine all the way to a touchdown which occurred without a landing clearance. The Investigation concluded that the poor performance of the pilots had been founded on a lack of prior analysis of the situation, poor CRM and non-compliance with system management and operational requirements.)
  • E55P, St Gallen-Altenrhein Switzerland, 2012 (On 6 August 2012 an Embraer Phenom 300 initiated a late go-around from an unstabilised ILS/DME approach at St. Gallen-Altenrhein. A second approach was immediately flown with a flap fault which had occurred during the first one and was also unstabilised with touchdown on a wet runway occurring at excessive speed. The aircraft could not be stopped before an overrun occurred during which a collision with a bus on the public road beyond the aerodrome perimeter was narrowly avoided. The aircraft was badly damaged but the occupants were uninjured. The outcome was attributed to the actions and inactions of the crew.)
  • DH8D, vicinity Kalmar Sweden, 2006 (On 6 April 2006, an incorrect response to a propeller malfunction, by the crew of an SAS Dash-8-Q400, resulted in an unstable single engine approach, and operation of the remaining engine outside limits. The aircraft landed safely at Kalmar, Sweden.)
  • F50, vicinity Luxembourg, 2002 (On 6 November 2002, a Fokker 50 operated by Luxair, crashed on approach to Luxembourg Airport following loss of control attributed to intentional operation of power levers in the ground range, contrary to SOPs.)
  • 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