Use of oxygen
43.—(1)  The pilot-in-command for an aircraft mentioned in regulation 3(1)(a) or (b) that has a non‑pressurised cabin must ensure that —
(a)when the aircraft is flying above flight level 100 up to and including flight level 130, and the duration of the flight at those altitudes is more than 30 minutes, all the flight crew members use oxygen;
(b)before the aircraft reaches flight level 130, the method of use of the oxygen provided in the aircraft is demonstrated to all passengers; and
(c)when the aircraft is flying above flight level 130 —
(i)all passengers and crew members are instructed to use oxygen; and
(ii)all the flight crew members continuously use oxygen.
(2)  The pilot-in-command for an aircraft mentioned in regulation 3(1)(a) or (b) that has a non‑pressurised cabin must not operate the aircraft above flight level 250.