Prohibition on Interference with Crewmembers

Section 91.11 prohibits any person from assaulting, threatening, intimidating, or interfering with a crewmember in the performance of the crewmember's duties on the aircraft. It is the primary federal regulatory hook used against unruly passengers, and it carries significant teeth when combined with 49 USC § 46504 (the criminal statute for interference with flight crew).

Who is a "crewmember": The FARs define crewmember as a person assigned to perform duty in an aircraft during flight time. This includes the flight crew (pilots), the cabin crew (flight attendants on Part 121/135), and any flight engineer or other assigned personnel. A jumpseating pilot not on duty is not a crewmember for § 91.11 purposes.

Enforcement reality: § 91.11 is regulatory — a violation supports an FAA civil penalty (currently up to $37,000 per incident per the FAA's Aviation Safety and Capacity Expansion Act updates). The criminal counterpart, 49 USC § 46504, makes interference with flight crew a felony punishable by up to 20 years in federal prison. The FAA's 2021 "Zero Tolerance" policy elevated enforcement during the pandemic-era spike in unruly passenger incidents, with civil penalties routinely reaching tens of thousands of dollars per violation.

The threshold is low: "Interfere" doesn't require physical contact — verbal threats, refusing to comply with lawful crew instructions, blocking the aisle during taxi, or repeatedly disregarding the seatbelt sign can each satisfy the standard. The FAA has issued penalty notices for actions ranging from refusing to extinguish a cigarette to physically assaulting a flight attendant.

Reference: FAA Special Emphasis Enforcement Program (Unruly Passenger Initiative); FAA Order 2150.3C for sanction guidance. FAA Unruly Passenger Data and Enforcement.