§ 91.15 Dropping objects.

Section 91.15 prohibits dropping any object from an aircraft in flight that creates a hazard to persons or property. It then carves out an exception: the PIC may drop an object if reasonable precautions are taken to avoid injury or damage to persons or property.

What "drop" covers: The reg covers any unattended release from the aircraft — fuel jettison, banner/sign release, water bucket drops on fires, candy at airshows, paratrooper drops, parachute jumps (governed separately by Part 105 but still bound by § 91.15 when the act creates hazard), agricultural application materials, sling-load releases.

The "reasonable precautions" standard: This is the operational core of the rule. Reasonable precautions vary by what is being dropped, the altitude, the location below, wind, and the proximity of people and property. The FAA has historically expected pilots to: (1) know what's below; (2) have a release point that accounts for drift and dispersion; (3) coordinate with ground personnel or LE if relevant; (4) operate at an altitude that gives the dropped item time to disperse or descend safely.

Fuel jettison and emergency releases: Fuel dump under emergency conditions is generally protected under § 91.3(b) (emergency authority) AND § 91.15 (reasonable precautions). The FAA has not pursued enforcement against fuel jettison made in the course of a legitimate emergency, but it has investigated fuel dumps at low altitudes over populated areas where alternative procedures were available — see the January 2020 Delta 89 incident over Los Angeles.

Reference: FAA Order 7110.65 (ATC) sections on fuel dump coordination; FAA Inspector Guidance on agricultural application dropping under Part 137.