Originally Posted by
flybywire380
For the 737NG, it appears that using 10 minute take-off thrust time limit compared against extended second segment with 5 minutes thrust gives the same limiting performance weight. If this is the case, why would one pay for the 10 minute AFM entry, when you could use extended second segment instead?
Nothing stops you from taking extended 2nd segment with the 10 min T/O thrust as well, which would be the main benefit I imagine anyway.
At the beginning of the 4th segment, you have to be with flaps retracted and thrust at MCT, so thereafter any extension in the T/O thrust time has no effect. If you simplify a bit and consider that 1st and 3rd segment are equal in both cases, you see that the 10-min T/O thrust enables you much longer 2nd segment, which means you can clear higher obstacles.
If any of that makes sense, anyway...