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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

  • A343, vicinity Paris CDG France, 2012 (On 13 March 2012, an A340-300 crew cleared for a Cat 3 ILS approach at Paris CDG with LVP in force failed to descend at a rate which would allow the aircraft to capture the ILS GS and at 2nm from the runway, when still 2500 feet above runway height, the ILS GS mode engaged on a false upper lobe of about 10° and as a result of the consequent rapid pitch up and speed reduction, aircraft control was almost lost. After a period of further confusion, a go around was initiated and the subsequent approach was uneventful.)
  • SW4, New Plymouth New Zealand, 2009 (A visual approach by a Swearingen SA227 at New Plymouth was rushed and unstable with the distraction of a minor propeller speed malfunction and with un-actioned GPWS warnings caused by excessive sink and terrain closure rates. After a hard touchdown close to the beginning of the runway, directional control was lost and the aircraft left the runway to the side before continuing parallel to it for the rest of the landing roll.)
  • MD83, Kandahar Afghanistan, 2012 (On 24 January 2012, a Swiftair Boeing MD83 about to touch down on runway 05 at Kandahar lost alignment with the extended runway centreline when initiating the daylight landing flare for a landing and a corrective roll resulted in the right wing tip striking the ground 20 metres prior to the runway threshold before completing the landing. The Investigation found that the prior approach had been unstable both at the prescribed ‘gate’ and thereafter and should have led to a go around. It was also found that neither the operator nor the crew were authorised to make the GPS approach used.)
  • B738, vicinity Amsterdam Netherlands, 2009 (On 25 February 2009, the crew of a Turkish Airlines Boeing 737-800 lost control of their aircraft on final approach at Amsterdam after they had failed to notice that insufficient thrust was being used to keep the aircraft on the coupled ILS glideslope. An attempt to recover from the resultant stall was not successful and the aircraft crashed. The Investigation concluded that a go around should have been flown from 1000 feet as the approach was already unstable and that the attempt at recovery after the stall warning was not in accordance with the applicable procedure or crew training.)
  • 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.)

... further results


Stabilised Approach Awareness Toolkit for ATC

Further Reading

CANSO

Part of the Stabilised Approach Awareness Toolkit for ATC