CLB power greater than TO power

[Levelmind]

Hello,

My question is: On either a NADP 1 or 2 departure, would it be acceptable to use a CLB thrust greater than the TO thrust, even though it is stated "This procedure involves a power reduction at or above the prescribed minimum altitude and delaying flap/slat retraction until the prescribed maximum altitude is attained." which leads to me think that a power reduction is necessary?

Also, as far as I'm aware some airlines, such as SWA never derate their climb (?), which would mean that if they derate their TO thrust a bit, CLB power will inevitably be greater than TO thrust, so how is that allowable if my first statement is valid?

Thanks in advance!

[White Knight]

For info: Often when we reduce thrust on the 380 at thrust reduction altitude the power increases. This happens when we have used a high Flex Thrust setting on take off. For a full thrust take off (performance or contaminated runway) the thrust will be less at climb power.

To complicate the matter a little more there are four choices of Climb Thrust; Full, Derate 1, Derate 2 or Derate 3 depending on the take-off weight.

Hope this helps a little - at least as far as the 380 works:ok:

[Levelmind]

Ok thanks. :-)

So even if you're flying, let's say, the NADP 1, it's still ok to have a climb thrust greater than the TO thrust?

[DaveReidUK]

Or, to put it the other way, is noise abatement best served by having takeoff thrust less than climb thrust ?

[Intruder]

Is ANYTHING best served by having takeoff thrust less than climb thrust?!?

While I recognize the need to reduce thrust for engine life considerations, reducing it below the level that will be used for a prolonged climb seems a bit ludicrous. That is especially since most other safety factors (excess thrust, stop margin, screen height, climb rate...) will also be reduced. While peak noise may be reduced, it will last longer, and it will be produced at lower altitudes for a longer time.

IMO, takeoff thrust reductions should be limited to the planned climb thrust.

[donpizmeov]

Intruder, all performance factors are satisfied with the takeoff thrust flex obtained from the takeoff performance application . Noise is also reduced. At 1000feet AGL, when climb thrust is selected, improved climb also reduces noise. When an aircraft that can take off at 575t on some trips, but only need 420t on shorter trips, huge takeoff thrust reductions are available.
Obviously this won't work for those little regional jets like 777 etc.

[Denti]

On the 737, if one choses to use full climb thrust, which is advised for fuel saving whenever an unrestricted climb is expected, it will pretty much always be higher than reduced take off thrust.

Apparently Engine life is not reduced by using full climb thrust after a 40% reduced take off.

NADP is just a profile, it says thrust reduction, as that was the normal thing to do for a very long time. However with todays engine apparently it is not longer the case.

One can fly NADP with fully reduced thrust, which actually increases the noise footprint farther out as the climb out is slower compared to full thrust, while still meeting the minimum gradient. Absolutely legal, as is increasing thrust at thrust reduction altitude.

[DaveReidUK]

One can fly NADP with fully reduced thrust, which actually increases the noise footprint farther out as the climb out is slower compared to full thrust, while still meeting the minimum gradient.

In fact the NADP procedures don't specify any minimum climb gradient (though of course the SID may well do).