Checklist design and procedures featured on the agenda of this week’s high-level ICAO safety conference following the fatal loss of a Boeing MD-82 at Madrid, and the extraordinary escape of an MD-83 in a near-identical incident a year before.
Spanish delegates, on behalf of European air transport authorities, have urged the application of safety management principles to checklist design.
Spanair flight JK5022 crashed in August 2008 after its crew failed to extend the MD-82's flaps. Investigators found that the pilots twice missed a specific check on the flap deployment while taxiing out for a departure which had already previously been interrupted by a technical problem.
The presentation to ICAO in Montreal states that checklists "continue to be long and protracted" and adds that they do not necessarily prioritise the most important items.
"It is not unusual that the sequence of safety-critical items to be verified does not reflect the safety hierarchy or the importance of the verification to be performed," it says.
While the Spanair accident was well-documented, Spanish authorities recently released conclusions on a lesser-known event at Lanzarote on 5 June 2007, in which an MD-83 operated by Austrian charter carrier MAP rolled back and forth excessively – up to 60° right and left – as the jet stalled after becoming airborne.
Lax procedures meant the pilots failed to deploy the aircraft’s flaps and slats. Nor had they conducted a check on the configuration warning system despite a specific requirement on the checklist.
Boeing estimated the aircraft’s stall speed, out of ground effect, at 161kt. It had lifted off at 145kt, with the stick-shaker activating, and started rolling at 159kt. The crew regained control and returned to Lanzarote, landing safely.
Spanish investigators found that the configuration warning did not sound because a circuit-breaker had inadvertently been left open, effectively leaving some of the aircraft’s systems in ‘flight’ mode even though it was still on the ground.
But the failure to stick rigorously to checklist procedures – some items were not read, but simply checked from memory – meant several clues to the aircraft’s inadequate readiness for flight were missed.
The ICAO paper suggests that flight-crew training "may not address with sufficient emphasis" the essential role of checklists and the need for strict adherence.
Linear, uninterrupted checklists are inconsistent with concurrent and frequently-interrupted flight-deck activity, it adds, and while checklist availability is considered a safety barrier, specific standard procedures to support the checklist process are absent: "In particular, clear procedures on how to proceed when the execution of a checklist is interrupted, and how to ensure checklists are completed after an interruption, are not always available."