Regulation Text
(a) No person may operate an aircraft so close to another aircraft as to create a collision hazard.
(b) No person may operate an aircraft in formation flight except by arrangement with the pilot in command of each aircraft in the formation.
(c) No person may operate an aircraft, carrying passengers for hire, in formation flight.
Research Notes
Section 91.111 prohibits operating an aircraft so close to another aircraft as to create a collision hazard. It also prohibits formation flight without prior arrangement among the participating pilots in command, and absolutely prohibits formation flight with passengers for compensation or hire.
Paragraph (a) — collision-hazard proximity: The reg captures the broad swath of close-proximity operations — passing too close to another aircraft on a parallel runway, low passes that overflight crowd or ground operations, slow approaches behind heavier traffic without adequate spacing. The standard is objective: 'so close as to create a collision hazard.'
Paragraph (b) — formation flight requires PRIOR arrangement: Formation flight is permitted only when each PIC has agreed in advance. The FAA's interpretation is that 'prior arrangement' means a briefed plan, not a spontaneous join-up. Formation arrivals at fly-ins typically require pre-published procedures and formation-qualified pilots. The Pilot's Formation Committee (PFAST) of the FAST organization sets the recognized formation training standards used at most airshows and warbird events.
Paragraph (c) — no formation with passengers for compensation: A pilot operating for compensation or hire may not carry passengers in formation flight. This applies to charter, sightseeing, and demonstration ops. It does NOT apply to Part 91 personal flights even if you're flying formation with friends; the prohibition is specifically tied to compensation.
Practical applications: Most general aviation pilots will encounter § 91.111 in three contexts: (1) traffic pattern spacing at busy fields; (2) air-to-air photography flights; (3) overflight of other aircraft on approach. The reg also undergirds the operational expectation behind ATC's 'maintain visual separation' clearances — the PIC remains responsible for not creating a collision hazard.
Reference: AIM 4-4 on ATC clearances and visual separation. FAA-H-8083-25 (PHAK) Chapter 5 on collision avoidance.
Amendment History
Amendment History Coming Soon
Every time this regulation changes, we'll record it here — the date, what was amended, and a plain-English summary of what shifted.