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From SKYbrary Wiki
Plan Continuation Bias
(Plan) Continuation Bias is the unconscious cognitive bias to continue with the original plan in spite of changing conditions.
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:
- BN2A, vicinity Bonaire Netherlands Antilles, 2009 (On 22 October 2009, a BN2 Islander suspected to have been overloaded experienced an engine failure shortly after departure from Curaçao. Rather than return, the Pilot chose to continue the flight to the intended destination but had to carry out a ditching when it proved impossible to maintain height. All passengers survived but the Pilot died. The cause of the engine failure could not be established but the Investigation found a context for the accident which had constituted systemic failure by the Operator to deliver operational safety which had been ignored by an inadequate regulatory oversight regime.)
- E145, Ljubljana Slovenia, 2010 (On 24 May 2010 the crew of a Regional Embraer 145 operating for Air France continued an unstable visual approach at Ljubljana despite breaching mandatory go-around SOPs and ignoring a continuous EGPWS ‘PULL UP’ Warning. The subsequent touchdown was bounced and involved ground contact estimated to have been at 1300fpm with a resultant vertical acceleration of 4g. Substantial damage was caused to the landing gear and adjacent fuselage. It was concluded that the type-experienced crew had mis-judged a visual approach and then continued an unstabilised approach to a touchdown with the aircraft not properly under control.)
- F100 / EC45, vicinity Bern Switzerland, 2012 (On 24 May 2012, a Fokker 100 descending visual downwind to land at Berne and an EC145 helicopter transiting the Bern CTR (Class 'D' airspace) VFR came within 0.7 nm horizontally and 75 ft vertically despite early traffic advice having been given to both aircraft. The Investigation attributed the conflict to the failure of the F100 crew to follow either their initial TCAS RA or a subsequent revised one and noted that although STCA was installed at Berne it had been disabled "many years before".)
- HUNT, manoeuvring, vicinity Shoreham UK, 2015 (On 22 August 2015 the pilot of a civil-operated Hawker Hunter carrying out a flying display sequence at Shoreham failed to complete a loop and partial roll manoeuvre and the aircraft crashed into road traffic unrelated to the airshow and exploded causing multiple third party fatalities and injuries. The Investigation found that the pilot had failed to enter the manoeuvre correctly and then failed to abandon it when it should have been evident that it could not be completed. It was concluded that the wider context for the accident was inadequate regulatory oversight of UK civil air display flying risk management.)
- A320, Harstad/Narvik Norway 2004 (On 25 November 2004, a MyTravel Airways Airbus A320 departed the side of the runway at Harstad, Norway at a low speed after loss of directional control when thrust was applied for a night take off on a runway with below normal surface friction characteristics. It was found that the crew had failed to follow an SOP designed to ensure that any accumulated fan ice was shed prior to take off and also failed to apply take off thrust as prescribed, thus delaying their appreciation of the uneven thrust produced.)
- 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.