There is one notable exception to the “always fasten your seat belt while seated” rule. When refueling with passengers on board takes place the “fasten seat belts” signs must be off and the flight crew must brief the passengers to unfasten the seat belts.

While the "official" point where you can unfasten your seatbelt is when the pilot turns off the "Fasten Seatbelt" sign—typically after the aircraft reaches its initial cruising altitude and the air is stable—safety experts and airlines in 2026 strongly advise keeping it fastened whenever you are seated. The primary reason for this is Clear Air Turbulence (CAT), which cannot be detected by radar and can occur without warning, causing the plane to drop hundreds of feet in seconds. If you are unbuckled during such an event, you could be thrown against the cabin ceiling, leading to serious injury. Legally, you are only required to have it fastened during taxi, takeoff, landing, and when the sign is illuminated. However, "not necessarily needing it" is a state of convenience for using the lavatory or stretching your legs; for the duration of the flight, the buckled seatbelt remains your primary defense against the unpredictable nature of high-altitude weather.