Widebody Transport
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Human Factors
Approaching number 1 for the runway; we had watched 4-5 departing and arriving aircraft. Spacing between arrivals and departure was large; maybe 2-3 miles. Number one and holding short of the runway; just as landing traffic passed by; I heard the controller say what sounded like 'can you accept immediate?' Clearing left (final) and confirming with Captain; I responded to the affirmative. There was no reply. I was watching the landing traffic roll out and clear when I heard the controller repeat the request; and I again responded affirmatively. At this point the Captain was saying I wasn't transmitting. I looked at my communication panel and realized we had begun moving into position as the Captain responded to Tower we were lining up to hold for immediate takeoff. I selected my mic button as the Tower ask if we were lining up on the runway. 'I responded affirmative' and Tower then cleared us for takeoff. On departure; we were asked to contact the Tower. I remained on departure frequency while the Captain talked to Tower. They said we had taxied into position without clearance and to be more careful. It all had happened quickly and with some language barrier combined with the communication mishap; the Captain's reply to Tower led me to believe he had heard a different clearance than me; but by then we had been cleared for Takeoff. I did not hear anything from the First Officer B or First Officer C during all this; but I may have missed something listening to the Captain speaking as well as the Tower transmissions. To the best of my knowledge; no other aircraft/traffic was affected.
First Officer reported taxiing into position on runway without clearance. The flight was subsequently cleared for takeoff.