What is required for a body to be in a state of equilibrium while flying?

A body is in a state of equilibrium while flying when the forces acting on it are balanced, resulting in no unaccounted acceleration. For an aircraft, this typically means that the lift generated must equal the weight, and the thrust must equal the drag.

When an aircraft is not turning, it maintains a steady flight path, and the forces acting upon it can be more easily quantified and balanced. This absence of a turning motion ensures that all the forces—lift, weight, thrust, and drag—are acting in a state that promotes equilibrium.

In contrast, if the aircraft is turning (as in a banked turn), the equilibrium is disrupted because a component of lift is redirected to provide the necessary centripetal force to maintain the turn. This scenario complicates the balance of forces and often leads to an imbalance that can result in an increase in load factor or variations in speed and altitude unless managed properly.

In summary, a body must not be turning to maintain a clear state of equilibrium, ensuring balanced forces and stable flight performance.