Hi everyone, On the MD-11, I can climb using gradient of say 3.3% instead of V/S while using a SID departure matching the real World procedures (usually out of Kingsford Smith - YSSY) . How do I do this on the 737? They depart over my work all day and are always using a gradual climb while over Sydney to reduce noise. Thanks Brett Williamson

Yeah the MD-11 had the flight path angle (FPA) option, You can always switch on flight path vector and adjust pitch accordingly. You could also use cutback which is there to reduce noise and it also needs a shallower gradient because the N1 limit is reduced.

SIDs specify a minimum climb gradient, normally for obstacle clearance (e.g. 34R departures out of Sydney require a steeper gradient because the domestic terminal and CBD are significant obstacles). Normally in the 737, you will be rocketing away on the initial climb out, so climb gradient isn't a significant factor. Normally the required climb gradient is factored in when doing Takeoff performance calculations (and if you use TOPCAT, it does in fact take into account obstacles). Cheers DZ

Thanks David, The 737's certainly aren't rocketing out over Homebush of a day. I was under the impression that to keep noise to a minimum across the suburbs of Sydney, an airliner would climb out at a say 3.3% gradient until it was no longer over residential areas. Then they would let loose. BW

Its not so much based on climb grade, rather engine thrust level. Airlines will use a derated takeoff and/or climb to reduce noise, and let the airplane ascend as much as it can.