The actions of Singapore Airlines pilots in continuing to fly to Singapore in a Boeing 777 after a confirmed tail strike on takeoff from Melbourne Airport last October have been exonerated and praised by an ATSB inquiry.
The ATSB found that the pilots had correctly determined that the aircraft’s pressurisation system had not been affected, and that they had continued the flight safely and in accordance with Boeing’s recommended action for dealing with such incidents.
The report is an interesting sequel to various tabloid media reports at the time insinuating that the pilot actions were unsafe or risky, and that they should have turned back immediately once Melbourne Airport confirmed that a tail strike protection device had left evidence of it being scraped along part of the runway.
The incident, on October 9 last year, occurred during wild weather with high gusty winds at Melbourne Airport. During the pre-flight external inspection of the 777-300 one of the pilots noted that “it was difficult to walk straight due to the wind.”
While taxying to their holding point for takeoff from runway 34 they saw two aircraft go around after abandoning approaches to the same runway.
The ATSB found that winds had been gusting to a maximum of 45 kt, and turbulence had been reported in the control zone.
During the take-off run, as rotation was initiated, the headwind component decreased resulting in the aircraft’s airspeed reducing below rotation speed. This airspeed reduction prolonged the time to lift-off, allowing the pitch attitude to exceed the tail skid contact attitude.
After take-off, air traffic control contacted the flight crew alerting them of a ‘possible tail strike’. With no TAIL STRIKE caution message displayed on the engine indication and crew alerting system the flight crew carried out the unannunciated tail strike non-normal checklist and determined the aircraft structural integrity was intact.
An inspection of the runway identified contact marks, consistent with a tail skid contact. Air traffic control advised the flight crew that ‘only superficial concrete debris were found’ during the runway inspection.
The flight crew discussed all the available information and considered their options. With the aircraft pressurisation system indicating no abnormalities the captain made the decision to continue to the destination. The remainder of the flight was uneventful. On arrival in Singapore engineers conducted a post-incident inspection of the aircraft. Damage was evident to the tail skid system indicating that a moderate energy skid contact had occurred during take-off.
The pilots used a reduced thrust engine setting for takeoff, as most jet airliners do when using suitably long runways. This saves fuel and engine wear.
The ATSB notes that had the pilots on this occasion used a higher thrust setting it would most likely have minimised the exposure of the 777 to the gusty wind conditions during rotation and liftoff.
The tail skid protection system contact with the runway was caused by airspeed stagnation at the critical moment. The pitch attitude of the 777 when it lifted off was 10.7 degrees nose up, exceeding the 8.9 degrees where a 777-300 will have a tail strike.
The report says that Singapore Airlines has since drawn pilot attention to Boeing’s recommendation to use a higher thrust and rotation speed during gusty and strong crosswind conditions.
However it concludes by saying that the Singaporean crew provided an excellent example of how to manage a non-normal situation and through good communication and decision making processes, were able to complete the flight without compromising safety.