What must be true for an aircraft to hover?

For an aircraft to achieve a hover, the key condition is that all forces acting on the aircraft must be in balance. This means that the upward thrust generated by the rotors (or wings, in the case of other aircraft types) must equal the downward force of gravity (the weight of the aircraft). When these forces are equal, the aircraft can maintain a stable position in the air without ascending or descending.

In a hover, the aircraft must counteract its weight effectively while also dealing with environmental factors such as wind, which can affect its stability. If the thrust did not equal the weight, the aircraft would either rise or fall rather than remain in a steady hovering position. Therefore, achieving an equilibrium of forces is crucial for successful hovering.