What does the term “visual line of sight” (VLOS) mean?

The term "visual line of sight" (VLOS) is defined in aviation regulations to ensure that the remote pilot can maintain a direct and unobstructed view of the UAS during its operation. This means that the pilot must visually observe the aircraft without the assistance of any visual aids, such as binoculars or telescopes, which allows the remote pilot to effectively monitor the flight, assess the airspace around the UAS, and maintain situational awareness. This is crucial for avoiding obstacles and other aircraft, ensuring the safety of the UAS operations, and adhering to regulations that promote safe drone flying practices.

The other options do not align with the specific requirements of VLOS. For instance, using binoculars to monitor the UAS does not meet the definition of VLOS since it involves aided vision. Similarly, the concept of a designated visual zone implies a confined area rather than the direct visual ability to see the UAS, and communication with ground observers does not pertain directly to the pilot's visual monitoring of the aircraft itself.