During the departure phase, what happens at the altitude between 400 and 1000 feet?

During the departure phase of flight, particularly between the altitudes of 400 and 1000 feet, the aircraft is typically in a critical transition stage after takeoff. This is when the pilot usually initiates the process of accelerating to the desired climb speed while also retracting the flaps that were extended during takeoff.

Flaps are deployed to increase lift at lower speeds during takeoff, but once the aircraft has gained sufficient airspeed and altitude, it is safe and efficient to retract them. This helps reduce drag and allows the aircraft to climb more effectively. The steepness of the climb can also be adjusted for optimal performance, balancing speed and altitude gain.

Thus, the correct response highlights that both acceleration and flap retraction occur within this altitude range, which is essential for establishing a stable flight path as the aircraft transitions from takeoff to climb. This operation ensures the aircraft maintains optimal performance following departure.