Singapore legislation
Regulation 57
of Air Navigation (121 — Commercial Air Transport by Large Aeroplanes) Regulations 2018
Regulation 57
Locking of flight deck door
Subregulation 1
An AOC holder must ensure that, for a flight of any large aeroplane that is equipped with a flight deck door, that door is closed and locked from the moment all external doors are closed following embarkation until the moment any external door is opened for disembarkation, except when the opening of the flight deck door is necessary to permit access to and egress by an authorised person.
Subregulation 2
An AOC holder must establish procedures for a cabin crew member of a large aeroplane described in paragraph (1) to discreetly inform the flight crew of any security situation which may arise in the aircraft cabin.