Noise abatement and wear on the engine. I, too, thought that this perhaps was an extreme measure for such a slight gain... i mean, how long is a plane on full t

Noise abatement and wear on the engine. I, too, thought that this perhaps was an extreme measure for such a slight gain... i mean, how long is a plane on full thrust on take-off? 15 secs? 20? But then a jet mechanic showed me some graph comparing wear and engine de-rates (the technical term for this less-than-100%-takeoff) and it has a CONSIDERABLE effect on the lifetime of the engine, far more than I was thinking.