The person who needs a Remote Pilot Certificate is the person who will act as remote pilot in command of a civil small unmanned aircraft operation under Part 107. Section 107.12(b) requires that certificate, with a small UAS rating, and §107.65 recency. Section 107.1 is what puts the flight in Part 107 in the first place. A recreational flight that truly meets 49 USC 44809 is outside this part, which is the comparison on the Part 107 versus TRUST page.
The role, not the job title
The certificate follows the remote-pilot role. A visual observer does not need it. An owner who never acts as remote pilot and never manipulates the controls does not need it merely by owning the aircraft. The person manipulating the controls needs either the certificate and recency, or direct supervision by a remote pilot in command who can immediately take direct control. Hiring a pilot, or calling someone "lead," does not create the certificate. Eligibility to receive one is a separate list in §107.61: age 16, English, and a physical and mental condition that does not interfere with safe operation, plus the knowledge test or the Part 61 training path. Those eligibility items are on the age and medical page.
The certificate also does not list the aircraft. A construction firm that buys a 4.5-pound drone to document site progress for clients, under Part 107, must have the aircraft registered before the first flight, with its unique registration number displayed legibly on an external surface. Listing the drone on the remote pilot's certificate is not a registration method. Insurance does not replace registration for a business-owned aircraft. The firm still needs a person who holds the certificate to act as remote pilot in command. The pilot still needs the aircraft to be registered. Those are parallel requirements, and a new airframe needs both before it works a paid site.
Operating limits bind both people
When a remote pilot supervises a colleague who has no certificate and who is manipulating the controls, §107.51 still applies to both of them. The opening sentence of that section names the remote pilot in command and the person manipulating the flight controls. Both must comply with the operating limitations: groundspeed not more than 87 knots (100 miles per hour), the altitude rule, 3 statute miles flight visibility from the control station, and the cloud distances of 500 feet below and 2,000 feet horizontal. A visual observer watching the aircraft does not take that duty off either person. The uncertificated colleague does not get a private set of limits because someone else holds the certificate.
Use a bridge inspection as the example. The certificated remote pilot stands with the colleague and can take the controller immediately, so the colleague may manipulate the controls. The aircraft is at 90 knots groundspeed because the colleague is trying to beat a wind gust. The remote pilot cannot say the speed limit is the colleague's problem alone. Section 107.51 binds both. The remote pilot stops the acceleration or takes control. "Only the person on the sticks" is the wrong reading, and "neither, if a visual observer is present" is the other wrong reading.
The client does not become the remote pilot
Section 107.19(b) makes the remote pilot in command directly responsible for, and the final authority as to, the operation. A real-estate client who says "I'm paying for this shoot, so I make the call, launch now before the storm" does not hold that authority. The remote pilot may decline or stop the flight if it cannot be conducted safely. Final authority does not move to the aircraft owner because the owner bought the drone. It does not move to the client because the flight serves the client's business. The rule does not require the flight to start.
That is the practical answer to "who needs the certificate" on a job site. The person who can say no is the remote pilot in command, and that person is the one who must hold it. The client needs a pilot. The client does not need, and does not hold, the remote pilot's authority by paying the invoice. How designation and the rest of §107.19 work is on the remote pilot in command page.
The traps are to certificate every bystander, to skip the certificate because the aircraft is registered or insured, and to let the payer call the launch. Certificate the remote pilot. Register the aircraft on its own external mark. Apply §107.51 to both the remote pilot and the person on the controls. Leave the go or no-go with the remote pilot.
Sample those items on the free practice test. The lessons are at pricing.