Visual line of sight is where crew roles and the see-and-avoid rule meet. § 107.31 requires that, with vision unaided by anything but corrective lenses, the aircraft be seen throughout the entire flight — in order to know its location, determine its attitude, altitude, and direction of flight, observe the airspace for other traffic or hazards, and confirm it endangers no one’s life or property. Chapter 1 introduced this requirement; the crew angle lives in § 107.31(b), which says that ability must be exercised throughout the flight by either the remote pilot in command together with the person manipulating the controls, or by a visual observer. Line of sight, in other words, is a job — and it can be held by the flying pair or handed to a dedicated observer.

When a visual observer is used, § 107.33 attaches conditions that keep the crew working as one set of eyes rather than several. The remote pilot in command, the person manipulating the controls, and the visual observer must maintain effective communication with each other at all times. The remote pilot in command must ensure the visual observer is actually able to see the aircraft in the way § 107.31 requires. And all of them must coordinate to scan the airspace where the aircraft is operating for collision hazards, and to maintain awareness of the aircraft’s position through direct visual observation. A visual observer is not a passive bystander with a good view — they are a linked part of the crew’s shared picture of the flight.

What a visual observer does not do is lift the requirement — it relocates who satisfies it. Using an observer is what lets the person on the controls glance down at a screen while someone keeps eyes on the aircraft, but the flight is still bound by line of sight: § 107.31 is met by the observer instead of the pilot, not set aside. Actually flying beyond visual line of sight is a different thing entirely, requiring a waiver of § 107.31 — the subject of the next section and of Chapter 8. The observer extends the crew’s reach without loosening the rule an inch.