The main cause of the Spanair Boeing MD-82 fatal accident at Madrid last year - failure to select flaps to the take-off setting - has occurred frequently, but because in many cases the aircraft was not lost the subject has not been prominent, says a new report by NASA Ames.
An examination of the US confidential aviation safety reporting system (ASRS) shows that, since 2000, 55 take-offs have been carried out unintentionally in the USA without take-off configuration having been set, but the crew got away with the error, NASA's Loukia Loukopoulos told the Flight Safety Foundation European Aviation Safety Seminar at Nicosia on 18 March.
Loukopoulos, with NASA colleagues Immanuel Barshi and Key Dismukes, found that continual distractions during the process of preparing for flight, from the crew's arrival at the aircraft to beginning the take-off roll, appear to be the common contributory factor in these events. The study's theme was "the hidden complexity of cockpit operations".
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From the ASRS database, and as a result of flying normal trips in the cockpit jump seat where they made notes, her team examined hundreds of cases in which crews forgot to carry out - or to complete - checks and procedures. This occurred because of normal - but often random - events that caused distractions for the crew.
Loukopoulos found that there is a far larger difference than is generally acknowledged between the "linear" set of procedures a crew is supposed to follow according to the flight manual at any given phase of flight, and what happens in the real world, with weather anomalies, radio telephony exchanges, changes to routeings or clearances, pressure to meet slot times, cabin crew co-ordination requirements and many other factors.
The study's recommendations boil down to a need for crews and airlines to realise that multi-tasking, while it may be inevitable, is a hazard in its own right and should be recognised as such. Procedures and checks should be simplified where possible, and crews should be trained to recognise when workload is reaching a distracting level and to compensate for it, by slowing down if necessary.
How distractions could lead to disaster
On the issue of failing to configure the aircraft for take-off, one of the aviation safety reporting system (ASRS) reports details a Boeing 737-800 taxi-out at a major US airport, in the course of which there were several breaks in the pre-take-off checklist because of distractions, starting with confusion about the cleared route to the runway holding point.
Just as the crew were going into the pre-take-off checklist, it became apparent that the cabin crew warning chime had failed. The ASRS report says: "We were cleared for take-off from Runway 01, but the flight attendant call chime wasn't working. I had called for the before take-off checklist, but this was interrupted by the communications glitch. On take-off, rotation and lift-off were sluggish. At 100-150ft [30-45m], as I continued to rotate, we got the stick shaker. The first officer noticed the no flap condition and placed the flaps to 5."
As in the Spanair case, the take-off configuration warning horn had failed to operate, and when the crew reached their destination they found the relevant circuit breaker had "popped". In the Spanair MD-82 case a circuit breaker had been intentionally tripped by the maintenance crew to isolate a faulty component, but the take-off configuration warning had been unknowingly disabled by the same action.
- Learmount: Fatal distractions
Dangerous cockpit distractions and how to deal with them is one of the subjects that will be addressed at the Flight International Crew Management Conference 2009, in London 30 November-1 December.
Source: Flight International
