Chapter 1 introduced the remote pilot in command as the person who holds the certificate that makes a flight legal. § 107.19 goes further: it makes that person the single point of accountability for everything that happens in the air. A remote pilot in command must be designated before or during the flight, and once designated, that person is directly responsible for and is the final authority as to the operation of the small unmanned aircraft system — not a shared responsibility, not a committee decision, one name on the line. That authority comes with specific duties. The remote pilot in command must ensure the aircraft poses no undue hazard — meaning unreasonable or excessive risk — to people, other aircraft, or property if control is lost for any reason. It must also ensure the whole operation complies with Part 107 (the FAA regulation governing small unmanned aircraft system operations, introduced in Chapter 1) and — critically — retain the actual ability to direct the aircraft, so that compliance stays possible, not just theoretical. The regulation does not name the cause of a loss of control. This chapter offers two everyday illustrations of what such a loss could involve: a failed battery, or a lost control-link signal — the radio connection between the aircraft and the control station that lets the remote pilot direct the aircraft's flight path.

That last duty explains why a crew can have more than one set of hands on the controls without more than one person in charge. § 107.12 allows someone other than the remote pilot in command to manipulate the flight controls, but only under the direct supervision of a remote pilot in command who can immediately take direct control of the flight. A trainee, a camera operator, anyone without a certificate — all can fly the aircraft in that sense, but the certificated remote pilot in command must be positioned to seize the controls the instant something goes wrong. Acting as the remote pilot in command itself, by contrast, always requires the certificate; there is no supervised version of holding final authority.

Visual observers, covered in Chapter 1 as an aid to keeping the aircraft in sight, fit into this same chain rather than beside it. § 107.33 requires the remote pilot in command, anyone manipulating the controls, and the visual observer to maintain effective communication at all times, and it puts the burden on the remote pilot in command specifically to ensure the observer can actually see the aircraft. All three are also required to coordinate — scanning the airspace for collision hazards and tracking the aircraft's position together. A visual observer's eyes extend what the remote pilot in command can see, but they never shift where responsibility sits.