Hot weather/crap performance
Two points - when BA substituted 747s for the Tristar that had a "heavy" landing, the first one provided was P & W engined - it only just got off from MPA, and at Ascension, because BA insisted on day time flights only, its take off from ASI was very marginal, in fact the Fire Crew commander had the fleet on the run at three quarters of the way down the runway.
V1 (decision speed) may well be a significant distance before the end of the runway since more distance is spent accelerating compared to the distance required to stop.
Also if a 4 engine suffers an engine failure in the event of a continued take off it's only lost 25% of the available thrust as opposed to a twin jet which has lost 50% - hence "pro rata" twins and tris have better performance on all engines compared to quads.
Also maybe the take off was made at reduced (aka assumed) thrust which might make the take off appear more "marginal".
PS Where is MPA?
