Registration is the first thing the law asks of a drone, and under § 48.15 the rule is blunt: no person may operate a small unmanned aircraft that is eligible for registration unless the owner has registered and marked it under Part 48. Chapter 1 noted this in passing; the detail that matters here is the one exception and who it leaves out. Section 48.15 does excuse an aircraft from registration — but only when it is operated exclusively under the recreational statute, 49 U.S.C. 44809, and weighs 0.55 pounds or less. Both halves must be true. The widely repeated idea that a drone under 250 grams “doesn’t need to be registered” is a recreational rule, and it evaporates the moment the flight is commercial.

That is the trap worth naming plainly: under Part 107, weight buys you nothing. A sub-half-pound drone flown for hire is not operating exclusively under 44809, so the recreational exemption never reaches it, and it must be registered exactly like a heavier aircraft. If you are flying under this book’s rules, assume every aircraft you fly needs a registration on file before it leaves the ground. Registration is also not open to everyone: § 48.20 limits it to aircraft that are not registered under a foreign country’s laws and are owned by a U.S. citizen, a lawful permanent resident, or a U.S.-organized entity, among the categories the section lists.

There are two kinds of registration, and Part 107 operators use the one that works aircraft by aircraft. Under § 48.100, a Certificate of Aircraft Registration is issued for the specific aircraft named on the application — each drone in a commercial fleet is registered individually and carries its own number. The recreational path, § 48.105, works the opposite way: a single registration covers all of the aircraft an individual owns and flies recreationally, under one number. So a hobbyist registers once as a person; a Part 107 operator registers each aircraft, and adding a drone to the fleet means adding a registration.