Every Part 107 flight lives inside a box, and its ceiling is 400 feet above ground level (AGL) — the altitude measured from the surface directly below your drone, not from sea level or from wherever you're standing. Crewed aviation operates under its own separate altitude floor: § 91.119(c) requires aircraft over non-congested areas to stay at least 500 feet above the surface, though aircraft may descend below that over open water or sparsely populated areas provided they stay at least 500 feet from any person, vessel, vehicle, or structure. Over congested areas or open-air assemblies of people, § 91.119(b) requires crewed aircraft to stay at least 1,000 feet above the highest obstacle within a 2,000-foot horizontal radius. These are the altitudes where crewed aircraft actually operate, and the 400-foot drone ceiling exists to keep unmanned aircraft below that traffic, cutting down the chance the two ever occupy the same airspace. The 400-foot ceiling has one notable exception — within a 400-foot radius of a structure, you may fly up to 400 feet above the structure's immediate uppermost limit. This allowance is called the structure exception, and it is key to practical work like tower inspections. This exception travels with the structure, though: if you drift outside that 400-foot radius, the ordinary 400-foot ceiling applies again immediately.

Speed is capped at 87 knots — 100 miles per hour — of groundspeed. The word matters: groundspeed is measured over the ground (your speed relative to the ground, as opposed to airspeed, your speed through the air), so a strong tailwind adds to your groundspeed even when your airspeed reads lower. The cap bounds the energy your aircraft carries into anything it might hit and keeps closing speeds manageable if crewed traffic appears.

The weather minimums protect the see-and-avoid system everything else depends on. You need at least 3 statute miles of flight visibility as observed from your control station — the rule defines this as the average slant distance (the line-of-sight distance from you to the object — measured at an angle — rather than the horizontal distance measured along the ground) at which prominent unlighted objects can be seen and identified by day, and prominent lighted objects by night. The aircraft must also stay at least 500 feet below and 2,000 feet horizontally from any cloud. An aircraft breaking out of a cloud has had no chance to see your drone; the clearances buy both of you reaction time.