Are passengers allowed to lie across vacant seats during take-off and landing?

Passengers are not allowed to lie across vacant seats during take-off and landing due to safety regulations established by the Federal Aviation Administration (FAA). During these critical phases of flight, all passengers must be seated with their seatbelts fastened and in an upright position. This requirement is in place to ensure that passengers are securely positioned to protect them in case of turbulence or an emergency situation. The need for safety equipment, like seatbelts, is heightened during take-off and landing, so it is imperative for everyone on board to adhere to these guidelines to minimize the risk of injury.

In this context, the other options suggest alternative scenarios under which passengers might be allowed to lie across seats, such as having permission or if they are children, but none of these situations align with FAA regulations that prioritize safety in the aircraft cabin. Therefore, the definitive answer is that passengers may not lie across vacant seats during take-off and landing.