My guess
Thanks for helping me put this into perspective HD.
Chatting to my colleagues who legged it out of their offices to see the spectacle (they honsetly heard it coming !!) The aircraft was approx 1/3 of the height that it normally clears the plant at.
I polled others - equally as inexperienced at spotting as I am - using the 150ft tower as a guide the overwhealming opinion was that it was no more than 300ft up as it came over the plant.
I have tried to take the steam out of peoples thoughts but when one senior manager on the north side of the plant thought it was coming in through his office window ("I thought my number was up you could see into the cockpit") something really did happen in this case.
IF it was lower than the "rules" would it have been reported as a matter of course ?
CVTD