Surprising ATC didn't initiate the crash alarm, but I don't know exactly what their rules are.
I am reminded of an incident over 40 years ago. I was a captain on 105 Squadron RAF flying Argosies. There was some military goings-on in southern Africa and we were authorised to operate from Matsapa, Swaziland using "tactical performance". Mataspa's runway was short in those days. Rotate speed could be lower than normal, none of that pansy 35 feet screen height and as for V1.....
One day, we were particularly heavy and the loading officer also shared doubts about the weight calculations. I briefed my crew that I would not necessarily rotate at Vtactical but would do so somewhere between Vtac and the normal VR - or at the end of the runway if that was reached first. Matsapa is on the top of a hill, so the plan after rotate, was get speed as quickly as possible. For those who are not pilots, an engine failure in the air below a certain speed spells trouble (The Argosy was not over-endowed with power despite its 4 RR Dart engines). So I would let the beast flop off the end of the runway and gain speed in the valley. My crew seemed very happy with the logic.
So off we went without problem disappeared from sight from the airfield. I must confess that I slightly (?) overdid the need for speed (well - I did take the opportunity for a bit of low-level sightseeing!) and re-appeared some two or three miles further on at not far short of Vne. Apparently the loading officer - still unsure about his calculations - was on tiptoe and nearly collapsed with relief when we finally re-appeared.
Jack Harrison