Singapore legislation
Regulation 44
of Air Navigation (125 — Complex General Aviation) Regulations 2018
Regulation 44
Flight crew communication
A CGAC holder must ensure that every person assigned duty as a flight crew member of an aeroplane to be operated for a complex general aviation operation, and who is required to be on flight deck duty on the aeroplane, communicates through boom or throat microphones when the aeroplane is flying at an altitude that is below the higher of —
(a)
15,000 ft; or
(b)
the transition level or altitude.