They were on fire just as they reached V1.
Plane was fully loaded with 38,000 LB of fuel for 12 hour flight to hawaii. Worst case scenario.
Pilots did the heroic thing - they tried to take off instead at 160 MPH to minimize collateral damage (highway and warehouses at the end of the runway) and crash and die somewhere else, instead of go beyond the runway at that speed. Accelerating a fully loaded jet plane at ground level beyond the runway has obvious consequences. They had one choice.
Instead, they clipped the UPS factory because they were so low, they tried to clear it but did not. Plane then hit the ground port wing down, shearing it off entirely, smearing a fireball of jet fuel across half a mile (not an exaggeration) before the plane flipped. Crew were likely dead by before this, footage shows the cockpit being slammed into the ground like a mousetrap by the flip once the port wing was gone and gravity took the starboard wing over.
Physics took over. Plane flipped and rolled upon loss of port wing, smearing a rolling fireball of the remaining fuel load from the starboard wing for another half a mile.
Louisville is now a firestorm as a result.
Respect to the flight crew; rest in peace, they made the best they could out of a really shitty scenario. They flew it all the way down.
Footage:
https://x.com/osinttechnical/status/1985845987684855969?s=46
https://x.com/faytuksnetwork/status/1985849267152699741?s=46
https://x.com/faytuksnetwork/status/1985848132500885995?s=46
https://x.com/faytuksnetwork/status/1985843126934614297?s=46
When the plane reaches V1, pilots take the hand off the throttle: they're committed to takeoff, even if an engine fails. It is better to take off and fix the problem or land again, than to smash into whatever is beyond the end of the runway.
Surely uncertainty about the situation contributes to defaulting to committing, but what if it's a passenger plane and at V1 pilots know they've lost power? Wouldn't veering into highway at 30 mph be weighted against certain, big loss of life?
Edit: I now see that this has been partially answered by uncle comment
The margin is for example that the plane must not just be able to fly, but also reach a minimum climb gradient to clear obstacles with a bit of safety margin. There is also an allowance for the time it takes from calling abort to actually hitting the brakes. And for example headwind is part of the calculation (it makes the takeoff distance shorter) but only 50% of the headwind is used in the calculations.
But all of those margins are not for the crew to use, the crew must just execute the procedure exactly as trained which means at V1 you're committed to continue the takeoff. And before V1 in case of an engine failure you have to hit the brakes to make sure you can stop before the end of the runway.