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:
- ULAC / A319 vicinity Southend UK, 2013 (On 18 July 2013, an Airbus A319 level at 2000 feet QNH in Class G airspace and being radar vectored towards an ILS approach at Southend in day VMC had a sudden but brief base leg encounter with a paramotor which was not visible on radar and was seen too late for avoiding action to be practicable, before passing within an estimated 50 metres of the A319. The paramotor pilot could not subsequently be traced. The Investigation made a safety recommendation to the UK CAA to "review the regulation and licensing of paramotor pilots".)
- B190, vicinity Bebi south eastern Nigeria, 2008 (On 15 March 2008, a Beech 1900D on a non-revenue positioning flight to a private airstrip in mountainous terrain flown by an inadequately-briefed crew without sufficient guidance or previous relevant experience impacted terrain under power whilst trying to locate the destination visually after failing to respond to a series of GPWS Alerts and a final PULL UP Warning. Whilst attributing the accident to the crew, the Investigation also found a range of contributory deficiencies in respect of the Operator, official charting and ATS provision and additional deficiencies in the conduct of the unsuccessful SAR activity after the aircraft became overdue.)
- B190, Blue River BC Canada, 2012 (On 17 March 2012, the Captain of a Beech 1900C operating a revenue passenger flight lost control of the aircraft during landing on the 18metre wide runway at destination after an unstabilised day visual approach and the aircraft veered off it into deep snow. The Investigation found that the Operator had not specified any stable approach criteria and was not required to do so. It was also noted that VFR minima had been violated and, noting a fatal accident at the same aerodrome five months previously, concluded that the Operators risk assessment and risk management processes were systemically deficient.)
- H25B, vicinity Owatonna MN USA, 2008 (On 31 July 2008, the crew of an HS125-800 attempted to reject a landing at Owatonna MN after a prior deployment of the lift dumping system but their aircraft overran the runway then briefly became airborne before crashing. The aircraft was destroyed and all 8 occupants were killed. The Investigation attributed the accident to poor crew judgement and general cockpit indiscipline in the presence of some fatigue and also considered that it was partly consequent upon the absence of any regulatory requirement for either pilot CRM training or operator SOP specification for the type of small aircraft operation being undertaken.)
- CRJ2, Barcelona Spain, 2011 (On 30 July 2011, an Air Nostrum CRJ200 continued a significantly unstable visual approach to Barcelona in the vicinity of a convective storm to a point where the aircraft commander considered that a go around would be less safe than continuing the approach. In an attempt to regain a viable vertical profile from above, sustained and very high rates of descent were flown triggering a continuous 16 seconds of EGPWS Mode 1 PULL UP Warnings which were completely ignored. The resultant very hard landing caused structural damage to the aircraft and the sole cabin crew sustained a minor injury.)
- 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.