Description

On 5 February 2012, an Airbus A340-300 (4R-ADG) being operated by SriLankan Airlines on a scheduled passenger flight from London Heathrow to Colombo, Sri Lanka and operated with an augmented flight crew was observed to become airborne much later than usual after accepting take off clearance from an intermediate point on the departure runway. The takeoff, carried out in daylight and with normal ground visibility, and the subsequent climb out were completed without actual incident but there was sufficient concern about operational safety to prompt an Investigation of the circumstances.

Investigation

A Field Investigation was carried out by the UK AAIB. There was a delay in the reporting of the event and, as a result of this, Flight Data Recorder (FDR) data had been overwritten and when the relevant OQAR disk obtained from the Operator was examined, it was found to be faulty and contained no data. However, ground radar recordings showed that the aircraft had become airborne 2650 metres +/- 50 metres from the start of the take off roll compared to a Takeoff Run Available (TORA) from that position of 2854 metres. The Investigation also calculated that, based upon the conditions at the time, the required take off run for a reduced thrust take off was 2268 metres using the maximum assumed temperature available of 38º C.