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Friday, December 16, 2011

Misdirected data check led to Jetstar A321 take-off incident

Australian carrier Jetstar has banned the practice of "bookmarking" pages in aircraft performance manuals, to stress the importance of pilots independently checking take-off data.

The decision came days after the crew of a Jetstar Airbus A321 performed an intersection take-off from Darwin using performance data for a full-length runway departure. While Runway 11 is 3,354m (11,000ft) long, the intersection take-off cut the available distance by more than 30%.

Australian Transport Safety Bureau (ATSB) investigators determined that, while the captain performed an external inspection, the co-pilot had consulted performance charts, to revise critical speeds, after detecting an error in take-off weight calculations.


jetstar a321, airteamimages.com
 © AirTeamImages.com

But the co-pilot inadvertently referenced the performance chart for the full-length runway, and then bookmarked the chart to assist the captain with cross-checking the revised data. "Such bookmarking was not precluded by the operator and some pilots used the practice to save time," said the ATSB.

When the captain checked the data, he automatically turned to the bookmarked page. With the error undetected, the aircraft took off from the taxiway B intersection and became airborne with 450m of runway remaining. It would have been unable to stop if the crew had rejected take-off at the nominated 160kt (296km/h) V1 decision speed.

Jetstar issued an internal notice five days after the 12 June incident, stating: "Bookmarking the page by the [non-flying pilot] is not acceptable. This practice must cease immediately."

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