Your V1 is essentially out the door.
Given the additional length you could still safely reject above the calculated V1, you just don’t know by how much.
So right after your calculated V1 you have a catastrophic failure for which you could have rejected had you requested new performance calculation.
Now you’re forced to take a sick puppy airborne.
Which is well and good in the sim but in the real world with a low overcast and a crosswind and 100 people screaming in the back it’s different.
Bit academic as there will literally only be a few seconds between the “old” V1 and the “new” V1 so realistically that window is really short but yes if it’s a substantial back taxi I would recalculate.
With a V1 of 160kts you’re moving at 253 feet second so somewhat arbitrarily if the backtrack and 180 turn and line up give me a gain of 1000’ I would recalculate.
So let’s say a total of 1500’ or more from the intersection I originally planned to use.
So here’s your solution:
When ATC assigns a runway and an intersection ask for both when you send for your performance on the ACARS.
Lets say airport is using 7L (10,000’) and 7R (8000’) for departure and I have not been assigned a runway I’d ask for both and once I’ve been assigned a runway I’ll cross out and circle or fold over.
Still leave the numbers legible in case they change their minds.
Which ATC never does
