500 above - that Gulfstream reluctance to depart from Northolt reminds me of an exciting takeoff in a 172 near Baltimore, Maryland. ( Cessnas have toe brakes. My usual chariot has heel brakes.)
I was going to rent a Beechcraft Sundowner, but when the seat was brought forward enough for my short little arms to reach the controls, the seatbelt no longer applied. We had a short trip across the bay with me in the righthand seat, just for the experience, and the instructor tried to frighten me with an engine failure scenario (not a problem if you usually don't have any engine to worry about). But on our return I said I guess I better rent your 172 instead, lets have a quick circuit just to make sure, so we strapped in after a hasty DI, and made for the runway. Instructor was in a hurry because his next lesson was due. I'm sure you can figure out what was set up to happen next.
Anyhow, rolled onto the runway, no traffic at all. Full power. Began to roll. Not a lot. In fact the brakes were grabbing at the wheels. Halfway down the runway we had only accelerated to 45 mph, the poor bird really wanted to fly, so I hoiked it off, and we roared over the treetops, collecting some sample leaves and scaring the squirrels. The instructor just sat there numb. I said, the brakes were grabbing, do you think the handbrake may still be set? He thought that might be the case. I said better land on the grass, just in case they are still set.....so I did, and asked him to do the next takeoff, which was without any problem. Halfway down the downwind leg, I realised what I had done wrong....and had been blaming it on the airplane.
They still rented it to me.