Originally Posted by
jbsay
...the perimeter restrictions make zero sense in a world in which long-haul narrow-bodies are no noisier when departing for a 2,500mi flight than when departing for a 600mi flight.
Actually not true. Transports use reduced T/O thrust when permitted since it both prolongs engine life (on the wing time) and reduces noise. A reduced thrust T/O make the plane's performance equal a maximum weight T/O for that runway on that day by doing exactly what it sounds like - reducing the thrust applied.
Jim