Crew rest compartment

A crew rest compartment (crew rest) is a section of an airliner dedicated for breaks and sleeping by crew members, usually located above or adjacent to the passenger compartment. Crew rest compartments are normally segregated, with separate compartments for the flight crew and the cabin crew.
On long flights, crew members may sleep in crew rest compartments during off-duty periods. Federal Aviation Regulations have provisions requiring crew rest areas be provided in order to operate a long flight by using multiple crew shifts.
Passengers are restricted from accessing crew rest compartments by regulations; their entrances may be secured by locks and may require ascending a ladder for access.
Crew rest compartments may not normally be used during taxi, takeoff, or landing maneuvers (TT&L). In flight crew rests that contain standard seats, an exception may be made to allow seated crew during TT&L.
In the United States, the Federal Aviation Administration (FAA) defines three classes of crew rest facilities, dependent on the number of crew and the duration of the flight. Crew rest periods may be provided in higher classed rest areas than required, for example some airplanes may not have a class 2 rest facility, providing breaks in a crew rest.
The FAA rest facility classifications from highest to lowest:
Crew rest design and safety considerations are similar between international regulators, for example the European Aviation Safety Agency (EASA) regulations for access control, communications, and signage are similar to those of the FAA's. By following such regulatory Bilateral Aviation Safety Agreements (which avoid contradictory minimum specifications), aircraft manufacturers can design crew rests to meet the requirements in many markets.