A pilot must coordinate thrust and what else to maintain level flight across a range of speeds?

To maintain level flight across a range of speeds, a pilot must coordinate thrust and the angle of attack. The angle of attack is the angle between the chord line of the wing and the relative wind. This angle is critical because it directly affects the lift generated by the wings.

As the speed of the aircraft changes, the required angle of attack to maintain level flight also changes. At higher speeds, less angle of attack is typically needed to produce sufficient lift because the faster airflow over the wings results in greater lift. Conversely, at slower speeds, the angle of attack needs to be increased to maintain sufficient lift.

By managing the angle of attack along with thrust, the pilot ensures that the aircraft remains in equilibrium, neither climbing nor descending, which is crucial for sustaining level flight.