Contribution of Unstabilised Approaches to Aircraft Accidents and Incidents

Contribution of Unstabilised Approaches to Aircraft Accidents and Incidents

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

On 28 April 2018, a Dassault Falcon F900B came into close proximity with a Beech B36T Bonanza at the uncontrolled VFR-only aerodrome at Bremgarten during its tailwind approach to runway 23 made without contacting the designated Flight Information frequency as the other aircraft was on approach to runway-in-use 05 and in contact with Flight Information. The Beech pilot took avoiding action by turning north and climbing in order to avoid a collision. The Falcon 900 crew had not prepared for the approach which was then unstabilised with late gear extension and multiple EGPWS ‘SINK RATE’ warnings annunciated.

On 15 January 2023, an ATR 72-500 positioning visually for an approach to Pokhara was observed to suddenly depart normal flight and impact terrain a few seconds later. All 71 occupants were killed and the aircraft destroyed by impact. A Preliminary Report published by the Accident Investigation Commission has indicated that a stall warning and subsequent loss of control was preceded by an apparently unintentional and subsequently undetected selection of both propellers to feather in response to a call for Flaps 30. The Training Captain in command was supervising the Captain flying during familiarisation training for the new Pokhara airport.

On 29 November 2017, a Boeing 737-900 on an ILS approach at Atlanta became unstable after the autothrottle and autopilot were both disconnected and was erroneously aligned with an occupied taxiway parallel to the intended landing runway. A go-around was not commenced until the aircraft was 50 feet above the ground after which it passed low over another aircraft on the taxiway. The Investigation found that the Captain had not called for a go around until well below the Decision Altitude and had then failed to promptly take control when the First Officer was slow to begin climbing the aircraft.

On 1 January 2020, an Airbus A350-900 made an unstabilised night ILS approach to Frankfurt in good visual conditions, descending prematurely and coming within 668 feet of terrain when 6nm from the intended landing runway before climbing to position for another approach. A loss of situational awareness was attributed to a combination of waypoint input errors, inappropriate autoflight management and communication and cooperation deficiencies amongst the operating and augmenting flight crew on the flight deck.

On 13 November 2020, a Boeing 727-100 configured for cargo operations veered partially off the landing runway at Kigali after a late touchdown on a wet runway before regaining it approximately 1,000 metres later. The Investigation concluded that viscous hydroplaning after touchdown which occurred a significant distance left of the runway centreline had been contributory but absence of a prior go-around was causal. It was also found that the flight crew licences were invalid and that there were significant discrepancies in respect of the aircraft registration, the status of the operator and the validity of the Air Operator Certificate. 

On 12 September 2020, during a largely autopilot-controlled ILS glideslope capture from above and despite being unstabilised after the crew had intentionally ignored required approach management procedures, a flight was continued without hesitation to a landing. The Investigation found that the operator’s oversight of operating standards relating to unstabilised approaches was systemically flawed and also insufficiently supportive of their ‘Evidence Based Training’ method used for pilot training. It was also noted that the Captain involved had stated to the Investigation that “he considered this flight as a non event”.

On 16 May 2013, a DHC6-300 on a domestic passenger flight made a tailwind touchdown at excessive speed in the opposite direction of the of 740 metre-long runway to the notified direction in use and, after departing the runway to one side during deceleration, re-entered the runway and attempted to take off. This failed and the aircraft breached the perimeter fence and fell into a river. The Investigation identified inappropriate actions of the aircraft commander in respect of both the initial landing and his response to the subsequent runway excursion and also cited the absence of effective CRM.

On 8 February 2019, a Piper PA46-350P overran the landing runway at Courchevel and collided with a mound of snow which caused significant damage to the aircraft but only one minor injury to a passenger. The Investigation noted the Captain's low level of experience but the investigation effort was primarily focused on the risk which had resulted from a commercial air transport flight being conducted without complying with the appropriate regulatory requirements for such flights and without either the passengers involved or the State Safety Regulator being aware of this.

On 2 May 2016, a Boeing 737-800 veered off the 2,500 metre-long landing runway near its end at speed following a night non-precision approach flown by the Captain. It then stopped on grass having sustained damage to both the left engine and landing gear. The Investigation noted that a significant but allowable tailwind component had been present at touchdown and found that the approach had been unstable, the approach and touchdown speeds excessive and that touchdown had occurred beyond the touchdown zone after applicable operating procedures had been comprehensively ignored in the presence of a steep authority and experience gradient.

On 7 August 2020, a Boeing 737-800 making its second attempt to land at Calicut off a night ILS approach with a significant tailwind component became unstabilised and touched down approximately half way down the 2,700 metre-long wet table top runway and departed the end of it at 85 knots before continuing through the RESA and a fence and then dropping sharply onto a road. This caused the fuselage to separate into three pieces with 97 of the 190 occupants including both pilots being fatally or seriously injured and 34 others sustaining minor injuries. Significant fuel spillage occurred but there was no fire.

 

Stabilised Approach Awareness Toolkit for ATC

Further Reading

CANSO

Part of the Stabilised Approach Awareness Toolkit for ATC

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