Which of the following is crucial for the safe operation of a drone?

Maintaining visual line of sight is essential for the safe operation of a drone because it allows the pilot to effectively monitor the drone's flight path, surroundings, and potential hazards. By keeping the drone within visual range, the operator can avoid obstacles, other aircraft, and ensure compliance with regulatory requirements. This practice enhances situational awareness, which is vital for making informed and timely decisions during flight.

In contrast, making sudden altitude changes can lead to loss of control, and flying at night without lights significantly increases the risk of collisions and inability to see the drone’s surroundings. Operating at maximum speed can also compromise safety by reducing the pilot’s ability to react to changing environments and obstacles. Thus, ensuring visual line of sight is a fundamental safety measure in drone operation.