Many moons ago, I was on a flight test on a 767-200/CF6-80C2B6. The aircraft was very light, only about 10 people on board, no interior, no water in the barrels, and B6 was the highest rating (~60k).
We were on condition at 35,000 ft./Mach 0.82 10 minutes after brake release!
Getting to the flight deck after takeoff was a bit like climbing a mountain.
