B-737 performance doubt

[lfrochao]

I have been looking information.with no results, about convine for take off, reduced thrust and improved climb on a very long runway,
Does any one can tell me if it is allowed for the 737-200 advanced?

[mutt]

Try doing your takeoff calculations based upon optimized V-speeds and you will get the result your desire.


Mutt.

[jpsingh]

The information is available in the B 737 Flight Ops Manual IIon performance or what is now known as the Flight Planning and Performance Manual. The Field Length limited Weight minus the Climb/ Obsacle limit weght is approximately 50% of the improved climb weight that can be added to the Climb limit weight subject to limitations. Please refer Boieng FLIGHT PLANNING AND PERFORMANCE MANUAL . The ADV version may have JT 8D- 9A or -15 OR -17/17A Engines so you will need to refer to the one applicable to you. For the JT8D-17A, the improved climb is covered in pages 1.2.4 to 1.2.10. Also the rEduced Take Off thrust is covered in the QRH Performance Inflight - General PI.20.9 . I hope that was useful ?:ok:

[CaptainSandL]

Steady on chaps, maybe what Ifrochao was asking is “Is assumed temp thrust reduction allowed with improved climb”.

My present company does not allow it but my previous one did. Personally I don’t see why you should not be allowed to do the two together. If you have excess runway and need to lift more weight then using improved climb will solve the problem. Fine, but why should you also have to do a full thrust take-off thereby increasing your chances of having an engine failure. If its stopping at V1 you are worried about then the numbers either say you can or can’t do it, there is no grey area. If you can’t then go full thrust, otherwise reduce your chances of having the V1 stop by using an assumed temp thrust reduction.

The two techniques are different and achieve different things, one gets you more take-off weight the other preserves engine life. If you can have both together then so much the better, it should be no problem on a very long runway but check your figures carefully.

This is the section on Assumed Temp from the FPPM (Page 1.1.4) for the 737-700. Note it does not prohibit use with improved climb. The section on Improved Climb was much longer so I didn’t paste it here, but it also makes no mention of not combining with an assumed temp:

Assumed Temperature Reduced Thrust
Regulations permit the use of up to 25% takeoff thrust reduction for operation with assumed temperature reduced thrust. Use of reduced thrust is not allowed on runways contaminated with standing water, ice, slush or snow. Guidance for setting reduced thrust is provided for the flight crew in the Performance Inflight Chapter of the QRH. Use of assumed temperature reduced thrust is not recommended if potential windshear conditions exist.

S & L

[LEM]

It's not forbidden to do the two together.

In certain companies, they routinely do this, as this will preserve engine life. Improved climb allows to assume even hotter temps.

And they also add derate on that!

Just make sure you have the correct tables. The mechanism in itself works pretty well.

On some runways, on the 300, using flaps one is even less restricting, so you'll end up eating a lot of runway... fells great to look like a 747!;)

(slightly less if you have to abort...) :O

LEM