If you wish to contribute or participate in the discussions about articles you are invited to join SKYbrary as a registered user

 Actions

Contribution of Unstabilised Approaches to Aircraft Accidents and Incidents

From SKYbrary Wiki

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

  • AT75, vicinity Cork Ireland, 2014 (On 2 January 2014, the crew of an ATR 72-212A lost forward visibility due to the accumulation of a thick layer of salt deposits on the windshield whilst the aircraft was being radar positioned to an approach at Cork on a track which took it close to and at times over the sea in the presence of strong onshore winds. The Investigation concluded that the prevailing strong winds over and near to the sea in relatively dry air with little visible moisture present had been conducive to high concentrations of salt particles at low levels.)
  • B735, vicinity Perm Russian Federation, 2008 (On September 13 2008, at night and in good visual conditions*, a Boeing 737-500 operated by Aeroflot-Nord executed an unstabilised approach to Runway 21 at Bolshoye Savino Airport (Perm) which subsequently resulted in loss of control and terrain impact.)
  • B734, Lahore Pakistan, 2015 (On 3 November 2015, a Boeing 737-400 continued an unstabilised day approach to Lahore. When only the First Officer could see the runway at MDA, he took over from the Captain but the Captain took it back when subsequently sighting it. Finally, the First Officer took over again and landed after recognising that the aircraft was inappropriately positioned. Both main gear assemblies collapsed as the aircraft veered off the runway. The Investigation attributed the first collapse to the likely effect of excessive shimmy damper play and the second collapse to the effects of the first aggravated by leaving the runway.)
  • B738, vicinity Memmingen Germany, 2012 (On 23 September 2012 a Ryanair Boeing 737-800 made a premature descent to 450 feet agl in day VMC whilst turning right onto visual finals for runway 24 at Memmingen after the FMS selected altitude had been set to a figure only 44 feet above runway threshold elevation of 2052 feet amsl. EGPWS Alerts of ‘Sink Rate’ and ‘Caution Terrain’ prompted initiation of a go around which, as it was initiated, was accompanied by a an EGPWS ‘TERRAIN PULL UP’ warning. The go around and a second successful approach to runway 24 were uneventful. The Investigation is not yet complete.)
  • E190, manoeuvring, northeast of Lisbon Portugal 2018 (On 11 November 2018, an Embraer 190-100LR just airborne on a post maintenance non revenue positioning flight became extremely difficult to control as it entered cloud despite the complete absence of any flight control warnings. After reversion to Direct Law, partial normal control was regained and, once visual, the flight was guided to an eventually successful landing. The Investigation found that the aircraft had been released from heavy maintenance with the aileron system incorrectly configured and attributed this primarily to the comprehensively dysfunctional working processes at the maintenance facility involved. Extensive airframe deformation meant the aircraft was a hull loss.)

... further results


Stabilised Approach Awareness Toolkit for ATC

Further Reading

CANSO

Part of the Stabilised Approach Awareness Toolkit for ATC