FAA guidelines Airplanes with a maximum payload capacity of more than 7,500 pounds, and a seating capacity between nine and 51 passengers, require one flight attendant. Airplanes with a maximum payload capacity of 7,500 pounds or less, and a seating capacity between 19 and 51 passengers, require one flight attendant.

Under strict FAA and international aviation regulations in 2026, a commercial aircraft cannot legally fly with passengers without the required number of flight attendants. Per 14 CFR 91.533, the "magic number" is based on passenger capacity, not actual seat occupancy: one flight attendant is required for aircraft with 20 to 50 seats, two for 51 to 100 seats, and an additional attendant for every 50 seats thereafter. While a plane is mechanically capable of flight with only pilots, flight attendants are mandatory safety and security officers responsible for emergency evacuations, medical first aid, and flight deck protection. If an airline cannot staff the required number of crew members due to illness or strikes, the flight must be canceled or the passenger count significantly reduced to meet the legal ratio. For "empty" ferry flights where no passengers are onboard, the plane can technically fly with only the pilots, but any revenue-generating flight requires a full safety crew.