Reduced T/o Thrust

[bflyer]

Hi gentelmen

i would appreciate your thoughts on the following

suppose conditions are suitable to perform a reduced thrust takeoff
suppose conditions are suitable to perform a flaps 5 takeoff for increased climb performance( normal T/O flaps is 15 deg)

would it make sense to perform a flaps 5 and reduced thrust takeoff simultaneously
note: no runway analysis charts provided to cover this scenario

[J.O.]

I am assuming that you're operating a large transport jet (a Boeing perhaps?). If you don't have runway analysis to cover a Flap 5 takeoff with reduced thrust, you have to ask yourself "what if I have a bad day and lose an engine at a critical moment?" Can you be sure the aircraft will perform properly in that case? Yes you may have full thrust available from the engine(s), but the takeoff with reduced thrust changes the departure path and may in fact result in a liftoff point which is too far down the runway to permit a safe climbout. Then you have to consider the regulatory implications. Depending on where your operation is registered, attempting that takeoff without valid performance figures for those conditions may in fact be a violation of the regulations.

So, unless you're a factory test pilot (and paid accordingly), I'd stick to performing takeoffs with valid data.

JMHO

[Old Smokey]

note: no runway analysis charts provided to cover this scenario

You're walking into a mine-field in No Man's Land, DON'T THINK ABOUT IT.

The required data could undoubtedly be obtained from Boeing, for a price, but would your operations justify the price? The only scenario which might make such a proposition worth-while would be if The Flaps 5 RTOW exceeded the Flaps 15 RTOW (which undoubtedly it would in many circumstances), and thus a lesser thrust might be required at a weight between the 2 limits with Flaps 5.

The GENERAL Boeing philosophy (and probably at Airbus also) is to provide reduced thrust data for the "NORMAL" day to day flap setting (in your case Flaps 15), but if increased weight is required by resorting to "unusual" configurations, e.g. Flaps 5, Packs OFF, Increased V2 speed schedule (Improved Climb), then the default is to go all the way to Full Takeoff Thrust (there are exceptions).

Regards,

Old Smokey

[411A]

In all jet transports that I've flown, the requirements for improved climb/overspeed takeoffs have been with full power selected.
No runway analysis charts available?
Forget the idea.
Work within the parameters that your operation demands, not outside.

[bflyer]

HI GUYS

I want to thank all of you..JO..OLD SMOKEY and 411A for your inputs on this matter
i fly a B727-200 and this input from you guys will be instrumental in settling the brainstorms and the what-if scenarios some of my crew members and me are having
again many thanks

[Amateur Turbines]

Hello all, I agree that you should not go down the path that has not been traveled.

I do have a question that falls under this topic though. How often are people doing reduced thrust take offs(De-rated) in order to increase MTOW due to Vmca/cg? Just wondering if this is very common place.

Thanks

[mutt]

I do have a question that falls under this topic though. How often are people doing reduced thrust take offs(De-rated) in order to increase MTOW due to Vmca/cg?

We do it everytime the runway is contaminated.

bflyer, when asking a question, its always better to state the aircraft type. On the B727, use of reduced thrust isnt permitted with improved climb.

Now if you were talking about the B777, there is nothing wrong with producing a "optimum" takeoff data chart which would include improved climb and then applying reduced thrust.

Mutt.