Heavy Transport
Flight Crew Air Transport Pilot (ATP)
Situational Awareness; Communication Breakdown; Workload
Conflict Ground Conflict; Less Severe; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Rejected Takeoff
Airport; Human Factors; Procedure
Night time takeoff Runway 23. Captain with FO on first flying leg of IOE and two relief Pilots for the flight. We were cleared onto the Runway 23 after a landing 737. FO taxied onto the runway for takeoff. Once aligned for takeoff I took control of the throttles. At this point I thought we were cleared for takeoff but apparently wasn't and advanced the power to 70% and pressed TOGA. At about that same time a relief pilot alerted the flying Pilots that the other plane that had just landed was cleared to back track to E on Runway 23; as well as the Tower alerting us to hold position. I disconnected the autothrottles and immediately brought them to idle. We were approximately 30 knots and had used up approximately 200 to 400 feet of Runway. The back tracking 737 entered the Runway and exited at E. Because we had started the takeoff roll and used up some of the usable Runway it was decided to taxi down RWY 23 to E and come back around to line up on RWY 23 full length. Fuel was not an issue.Looking back; somehow the clearance to Takeoff or the non-clearance was lost in the translation. The controllers in FNLU most often use non-standard phraseology; with an accent not easily understood. Coupled with higher than normal workloads due to a new hire first leg. The flight was late and had been delayed from the previous day. Assumed situational awareness with the airport and runway environment. Generally in past practice; FNLU hold the landing traffic in the holding bay after landing and does not have 2 planes on the runway at the same time.What 'saved' the situation was good CRM and situational awareness of the relief pilots.
[Report narrative contained no additional information.]
Air carrier flight crew reported beginning their takeoff roll too early with an aircraft that was cleared to back taxi was occupying the runway.