Which acronym is used to refer to the visual line of sight necessary for flying an unmanned aircraft?

The correct acronym for referring to the visual line of sight necessary for flying an unmanned aircraft is VLOS, which stands for Visual Line of Sight. This term is critical in unmanned aircraft operations as it indicates that the operator must maintain direct visual contact with the drone without the use of any visual aids, apart from corrective lenses if needed.

This requirement ensures that the operator can effectively monitor the aircraft's position and the surrounding airspace to ensure safety and compliance with regulations. It enhances situational awareness and helps in avoiding obstacles, other aircraft, and ensuring a safe flight experience.

The other acronyms listed do not pertain to the concept of maintaining visual line of sight during drone operations. VOR (VHF Omnidirectional Range) is used in aviation for navigation purposes, while VR (Virtual Reality) references technology used in immersive environments, and VO (Visual Observer) refers to a person who assists the drone operator by maintaining VLOS, but does not itself describe the visual line of sight concept.