If an engine fails on an aircraft carrier, V1 is defined as the speed at which the decision to continue the flight has been made. V1 is a quicker and more efficient method of informing the necessary people that the pilot has committed to continue flying.
V1 is also known as the speed that a pilot needs to decide whether they’re going to abort or not if they’re going to stop on a runway. This decision is made by looking at several factors, such as the length of the runway, temperature, if there are any obstacles in the plane’s way, the weight of the plane, and the runway slope.
Pilots will say ‘rotate’ to inform the necessary people that the airplane has reached its predetermined rotation speed. This is often abbreviated to VR, which is the speed at which the control can be inputted to lift the nose from the runway and into the air.
Before V1 has been reached, takeoff can be aborted if needed. The pilot stating ‘V1 Rotate’ therefore means that the aircraft has reached the predetermined speed at which takeoff cannot be aborted as well as the correct rotation speed. An aircraft can now take off into the air as all of the correct speeds have been reached.