Rayment moved the throttle forward slowly and released the brakes; the plane began to accelerate, and radio officer Bill Rodgers radioed the control tower with the message "Zulu Uniform rolling". The plane threw up slush as it gathered speed, and Thain called out the plane's velocity in 10-knot increments. At 85 knots, the port engine began to surge again, and he pulled back marginally on the port throttle before pushing it forward again. Once the plane reached , he announced "V1", at which it was no longer safe to abort take-off, and Rayment listened for the call of "V2" (), the minimum required to get off the ground. Thain expected the speed to rise, but it fluctuated around 117 knots before suddenly dropping to , and then . Rayment shouted "Christ, we won't make it!", as Thain looked up to see what lay ahead.