During which phase of flight is aerodynamic drag at its highest?

During the takeoff phase of flight, aerodynamic drag is at its highest primarily due to the aircraft being in a low-speed environment while generating maximum lift to become airborne. During takeoff, the aircraft is typically at a high angle of attack to generate the necessary lift, which increases induced drag. Additionally, the configuration of the aircraft—such as the flaps being deployed to enhance lift at lower speeds—contributes to higher overall drag.

In contrast, during cruising flight, the aircraft has reached a stable speed where drag is minimized for efficient flight. In climb, while the aircraft is also producing lift, it may not experience as high drag as during takeoff because it tends to have a higher speed compared to when it first leaves the ground. In descent, the aircraft often operates at lower angles of attack and may utilize drag devices differently, also contributing to lower overall drag compared to takeoff. Thus, takeoff is characterized by a unique combination of performance factors that leads to peak aerodynamic drag.