Accidents

Qantas Boeing 737 Take-Off

Two independent and inadvertent data entry errors meant weight used when calculating take-off performance was 10 tonnes less than actual weight. Tail strike.

On 1 August 2014, a Qantas Boeing 737-838 aircraft commenced take-off from Sydney Airport, New South  Wales. The flight was a scheduled passenger service from Sydney to Darwin, Northern Territory.

While the aircraft was climbing to cruise level, a cabin crew member reported hearing a “squeak” during  rotation. Suspecting a tail strike, the flight crew conducted the tail strike checklist and contacted the  operator’s maintenance support. With no indication of a tails trike, they continued to Darwin and landed  normally. After landing, the captain noticed some paint was scraped off the protective tailskid. This  indicated the aircraft’s tail only just contacted the ground during take-off.

The Australian Transport Safety Bureau (ATSB) found the tail strike was the result of two independent  and inadvertent data entry errors in calculating the take-off performance data. As a result, the take-off  weight used was 10 tonnes lower than the actual weight. This resulted in the take-off speeds and engine  thrust setting calculated and used for the take-off being too low. Hence, when the aircraft was rotated, it  overpitched and contacted the runway.

The ATSB also identified that the Qantas procedure for conducting a check of the Vref40 speed could be  misinterpreted. This negated the effectiveness of that check as a defence for identifying data entry errors.  In this case, uncorrected errors affected the integrity of the data used to calculate take-off parameters.

This incident highlights the importance of the integrity and verifiability Data Properties, with respect to the  data used to calculate take-off performance data.

Links 

http://www.atsb.gov.au/publications/investigation_reports/2014/aair/ao-2014-162.aspx
(accessed 29  November 2017).