Flight History
On 2 June 2007, a Boeing 747-300 aircraft, registration HZ-AIT, operated a scheduled passenger flight from Singapore to Riyadh. The aircraft departed from Runway 20C at Singapore Changi Airport at approximately 2012 hours local time. The Take-Off Run Available (TORA) for Runway 20C had been reduced to 2,500 m due to runway resurfacing work. The flight crew, consisting of a Pilot-in-Command, First Officer, and Flight Engineer, had been briefed by the flight despatcher about the shortened runway. The crew also received information via the ATIS broadcast confirming the reduced TORA.
The crew used Module Table Take-Off and Landing (MTTL) charts to determine take-off performance. The charts provided data for various runways and lengths, but the format was unfamiliar to the crew. The First Officer consulted the Pilot-in-Command to identify the correct column for the reduced runway length (20CT). However, the First Officer inadvertently read data from the column for the full runway length (20C).
Damage and Events
After the aircraft took off, the runway controller observed that the runway end marker board lights had extinguished. Inspection revealed that the first row of 13 marker boards, located 260 m from the temporary runway end lights, was badly damaged. The second row of five marker boards remained intact, but red cones on either side were displaced. Workers at the runway resurfacing site reported that the aircraft flew low overhead, causing them to squat. The crew was unaware of the incident until a Kuala Lumpur air traffic controller queried them about the take-off. The aircraft later landed in Riyadh, and an inspection did not reveal any damage. No passengers or crew were injured.
Analysis and Probable Cause
The Air Accident Investigation Bureau of Singapore classified this occurrence as a serious incident. The investigation identified the following significant factors:
- The crew used a take-off weight limit intended for a full-length runway instead of the reduced runway length.
- The crew did not cross-check the take-off performance data against the actual reduced runway length.
- The MTTL chart format was unfamiliar to the crew, and they had not been briefed on the format change.
The incident highlights the importance of correct data interpretation during take-off performance calculations.