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Continuation Bias

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Plan Continuation Bias

Article Information
Category: Human Behaviour Human Behaviour
Content source: SKYbrary About SKYbrary
Content control: SKYbrary About SKYbrary

Definition

(Plan) Continuation Bias is the unconscious cognitive bias to continue with the original plan in spite of changing conditions.

Discussion

Unconscious bias in thinking leads to a pilot or controller following the originally-intended course of action. This bias appears to be stronger as the culmination of a task nears, for example during the flying of an approach to land or the maintenance of the planned separation between aircraft sequenced for approach to a particular runway.

Continuation Bias may have the effect of obscuring subtle cues which indicate that original conditions and assumptions have changed. It may also act in combination with other cognitive biases.

Accidents and Incidents

SKYbrary includes the following reports relating to events where continuation bias was considered to be a factor:

  • C550, vicinity Cagliari Sardinia Italy, 2004 (On 24 February 2004, a Cessna 550 inbound to Cagliari at night requested and was approved for a visual approach without crew awareness of the surrounding terrain. It was subsequently destroyed by terrain impact and a resultant fire during descent and all occupants were killed. The Investigation concluded that the accident was the consequence of the way the crew conducted the flight in the absence of adequate visual references and with the possibility of a ‘black hole’ effect. It was also noted that the aircraft was not fitted, nor required to be fitted, with TAWS.)
  • C310, Hawarden UK, 2013 (On 15 November 2013, a privately operated Cessna 310 about to land at Hawarden crashed after power was lost from one engine and the experienced pilot appeared to have attempted to initiate a go around rather than land on the grass next to the runway. The Investigation found that both main fuel tanks were effectively empty after normal fuel use during the flight and since unused fuel remained in the auxiliary tanks, it was concluded that fuel starvation attributable to en route fuel system mismanagement had occurred. The other engine had been at full power but with fuel starvation imminent.)
  • B737 / F100, vicinity Geneva Switzerland, 2006 (On 29 December 2006, Geneva ATC saw the potential for runway 23 conflict between a departing 737 and an inbound F100 and instructed them to respectively reject take off and go around respectively. Although still at a relatively slow speed, the 737 continued its take off and subsequently lost separation in night IMC against the F100. The Investigation noted that take off clearance for the 737 had been delayed by a slow post-landing runway clearance by a business jet and that the 737 had not begun take off after clearance to do so until instructed to do so immediately.)
  • B737, New York La Guardia USA, 2013 (On 22 July 2013 the Captain of a Boeing 737 failed to go around when the aircraft was not stabilised on final approach at La Guardia and then took control from the First Officer three seconds before touchdown and made a very hard nose first touchdown which substantially damaged the aircraft. The Investigation concluded that the accident had been a consequence of the continued approach and the attempt to recover with a very late transfer of control instead of a go around as prescribed by the Operator. The aircraft was "substantially damaged".)
  • B738, Perth Australia, 2008 (On 9 May 2008, a Boeing 737-800 made a low go around at Perth in good daylight visibility after not approaching with regard to the temporarily displaced runway threshold. A second approach was similarly flown and, having observed a likely landing on the closed runway section, ATC instructed a go around. However, instead, the aircraft flew level at a low height over the closed runway section before eventually touching down just beyond the displaced threshold. The Investigation found that runway closure markings required in Australia were contrary to ICAO Recommendations and not conducive to easy recognition when on final approach.)
  • more


Related Articles

Further Reading

  • The “Barn Door” Effect by C. West, Ph.D., NOAA - a paper about pilots’ propensity to continue approaches to land when closer to convective weather than they would wish to get while en route.