Aircraft Flight Operation Regulations Article 123

Aircraft intended to be operated at a cabin pressure altitude higher than 10,000ft shall be equipped with oxygen storage and dispensing apparatus capable of storing and dispensing the oxygen supplies. Aircraft intended to be operated at flight altitudes higher than 10,000ft shall be provided with means of maintaining a cabin pressure altitude lower than 10,000ft or shall be provided with oxygen supplies in compliance with Article 77. Pressurized aircraft operated above 25,000ft shall be equipped with a device to provide positive warning to the pilot of any dangerous loss of pressurization.Aircraft for which the certificate of airworthiness was first issued on or after 9 Nov 1998, and which are intended to be operated at flight altitudes higher than 25,000ft, or which, if operated at flight altitudes of 25,000ft or lower, cannot descend safely within four minutes to a flight altitude of 13,000ft, shall be provided with automatically deployable oxygen equipment and oxygen supplies in compliance with Article 77. The total number of oxygen dispensing units shall exceed the number of passenger and cabin crew seats by at least 10 per cent.All flight crew members of pressurized airplanes operating above an altitude higher than 25,000ft shall have available at the flight duty station a quick-donning type of oxygen mask which will readily supply.