Question.....if balanced field for the day is 5000ft on a ten thousand ft runway...could you calculate max V1 to just make the stopway on a rejected take off on that runway?
Did anyone say you can't? As long as the V1 is below Vmbe and V1stop and Vr.
But then if you want to abort after Vr... that's a different story... I'd do it if I can't even reach V2 and decelerating if I still got the fence in front of me. If the fence is behind... well, pray...
Multiple engine failure etc? Well, if you are sure you cannot attain safe flight (for a safe return), just stop and pray you won't hit the petrol station on the other side of the fence (even if there is an extra 5000ft clearway after the 5000ft runway remaining).
The later shows that the pilot has more discretion because he has more time, more options...To purposely take away those options by choosing a shorter runway, using Flex, adding weight...adds risk...I didn't say dangerous, I said risk...
Flex is dangerous? *bangs head on table*
Let's put it this way, estimated value of risk from FLX / estimated value of savings from FLX. As long as your take off performance is legal, and your climb numbers are OK, if that equation yields an answer of <1, then FLEX is the way. If >1, well, the insurers will surely have a word with management.
It won't add another line the checklist...
PK-KAR