Definition
A lighter-than-air aircraft that is not engine-driven and that sustains flight through the use of either gas buoyancy or an airborne heater, drifting with the wind rather than being steered along a chosen course.
Plain English
A balloon with no engine. It floats because the air or gas inside is lighter than the air around it, and it goes wherever the wind takes it.
Context Anchor
Seen in FAA certificate, medical, and operating rules when balloon flying is treated differently from airplane or helicopter flying.
Derivation
Called 'free' because the balloon is not tethered to the ground and is not powered — it moves freely with the air mass. This distinguishes it from a captive or tethered balloon, which is held in place by a line.
Why Pilots Care
Free balloon operations fall under their own set of FAA rules, including specific pilot certificate categories and medical requirements. A pilot operating only a free balloon may not need the same level of medical certification as one flying powered aircraft.
Intuition Check
Free does not mean no cost here. It means the balloon is not tethered; once launched, it moves with the wind rather than being held in place.
Example Sentence 1
Because he flew only a free balloon, he was able to operate under the medical requirements specific to that category.
Example Sentence 2
A free balloon pilot must control altitude by venting gas or releasing ballast to change altitude.