Supplemental oxygen — pressurised flying machines
4.—(1) Pressurised flying machines operated at flight altitudes for which an oxygen supply is required in accordance with sub-paragraph (2) must be equipped with oxygen storage and dispensing apparatus capable of storing and dispensing the required oxygen supplies.
(2) Pressurised flying machines operated above flight altitudes at which the pressure altitude in the passenger compartments is above 10,000 feet must carry enough breathing oxygen to supply—
(a)all crew members and—
(i)100% of the passengers for any period when the cabin pressure altitude exceeds 15,000 feet, but in no case less than 10 minutes’ supply;
(ii)at least 30% of the passengers, for any period when, in the event of loss of pressurisation and taking into account the circumstances of the flight, the pressure altitude in the passenger compartment will be between 14,000 feet and 15,000 feet; and
(iii)at least 10% of the passengers for any period in excess of 30 minutes when the pressure altitude in the passenger compartment will be between 10,000 feet and 14,000 feet; and
(b)all the occupants of the passenger compartment for no less than 10 minutes, in the case of aeroplanes operated at pressure altitudes above 25,000 feet, or operated below that altitude but under conditions that will not allow them to descend safely to a pressure altitude of 13,000 feet within 4 minutes.
(3) Pressurised flying machines operated at flight altitudes above 25,000 feet must, in addition, be equipped with a device to provide a warning indication to the flight crew of any loss of pressurisation.