During takeoff, V1 must be:

In the context of aircraft takeoff procedures, V1 is a crucial speed that refers to the decision speed during takeoff. It represents the maximum speed at which a pilot can safely reject a takeoff. The understanding of V1 is tied closely to the concepts of VMCG (minimum control speed on the ground) and VR (rotation speed).

For a safe takeoff, V1 must be positioned such that it is not less than VMCG. This ensures that in the event of an engine failure before V1, there is sufficient controllability of the aircraft, allowing the pilot to maintain direction and control on the runway. If V1 were to be less than VMCG, the aircraft may become uncontrollable during a rejected takeoff, leading to a potentially dangerous situation.

At the same time, V1 must also be less than VR. This means that once the aircraft reaches VR, the pilot should initiate the rotation to lift off. If V1 were to exceed VR, it would mean that the aircraft would not have adequate speed to safely rotate and take off, which could compromise the safety of the flight.

Therefore, stating that V1 must be not less than VMCG or greater than VR encapsulates the essential safety parameters