What tendency occurs as an aircraft's speed increases from static conditions related to engine thrust?

As an aircraft's speed increases from static conditions, engine thrust generally behaves in a specific way due to the interaction between thrust and aerodynamic drag. When an aircraft first begins to move from a static position, the engines are producing a certain amount of thrust. However, as speed increases, the aircraft encounters increasing aerodynamic drag—particularly from the airframe and any lift devices.

This drag creates a condition where the initial thrust may not necessarily be sufficient to overcome the increase in drag at low speeds, thus leading to a temporary drop in effective thrust. As the aircraft continues to accelerate and moves beyond that initial phase, the thrust then starts to increase again, as the engines begin operating more efficiently at higher speeds.

This phenomenon is typical of turbine engines in aircraft, where they may experience a lag in thrust response until they fully spool up to speed. Therefore, the correct choice identifies this initial drop in thrust followed by an increase as speed rises. Understanding this tendency is crucial for flight engineers as it impacts performance calculations during takeoff and climb phases of flight.