Page 386 - UK Air Operations Regulations 201121

Part CAT - ANNEX IV - Commercial Air Transport Operations

(d) The total number of dispensing units and outlets referred to in (b)(3) and (c) shall exceed
the number of seats by at least 10 %. The extra units shall be evenly distributed throughout
the passenger compartment.
(e) Notwithstanding (a), the oxygen supply requirements for cabin crew member(s), additional
crew member(s) and passenger(s), in the case of aeroplanes not certified to fly at altitudes
above 25 000 ft, may be reduced to the entire flying time between 10 000 ft and 13 000 ft
cabin pressure altitudes for all required cabin crew members and for at least 10 % of the
passengers if, at all points along the route to be flown, the aeroplane is able to descend
safely within four minutes to a cabin pressure altitude of 13 000 ft.
(f) The required minimum supply in Table 1, row 1 item (b)(1) and row 2, shall cover the
quantity of oxygen necessary for a constant rate of descent from the aeroplane’s
maximum certified operating altitude to 10 000 ft in 10 minutes and followed by 20 minutes
at 10 000 ft.
(g) The required minimum supply in Table 1, row 1 item 1(b)(2), shall cover the quantity of
oxygen necessary for a constant rate of descent from the aeroplane’s maximum certified
operating altitude to 10 000 ft in 10 minutes followed by 110 minutes at 10 000 ft.
(h) The required minimum supply in Table 1, row 3, shall cover the quantity of oxygen
necessary for a constant rate of descent from the aeroplane’s maximum certified operating
altitude to 15 000 ft in 10 minutes.

CAT.IDE.A.235 AMC1 Supplemental oxygen — pressurised aeroplanes
DETERMINATION OF OXYGEN
(a) In the determination of the amount of supplemental oxygen required for the routes to be
flown, it is assumed that the aeroplane will descend in accordance with the emergency
procedures specified in the operations manual, without exceeding its operating limitations,
to a flight altitude that will allow the flight to be completed safely (i.e. flight altitudes ensuring
adequate terrain clearance, navigational accuracy, hazardous weather avoidance, etc.).
(b) The amount of supplemental oxygen should be determined on the basis of cabin pressure
altitude, flight duration and on the assumption that a cabin pressurisation failure will occur
at the pressure altitude or point of flight that is most critical from the standpoint of oxygen
need.
(c) Following a cabin pressurisation failure, the cabin pressure altitude should be considered
to be the same as the aeroplane pressure altitude unless it can be demonstrated to the
CAA that no probable failure of the cabin or pressurisation system will result in a cabin
pressure altitude equal to the aeroplane pressure altitude. Under these circumstances, the
demonstrated maximum cabin pressure altitude may be used as a basis for determination
of oxygen supply.
CAT.IDE.A.235 AMC2 Supplemental oxygen — pressurised aeroplanes
OXYGEN REQUIREMENTS FOR FLIGHT CREW COMPARTMENT SEAT OCCUPANTS AND CABIN
CREW IN ADDITION TO THE REQUIRED MINIMUM NUMBER OF CABIN CREW
(a) For the purpose of supplemental oxygen supply, flight crew compartment seat occupants
who are:
(1) supplied with oxygen from the flight crew source of oxygen should be considered as
flight crew members; and
(2) not supplied with oxygen by the flight crew source of oxygen should be considered
as passengers.
(b) Cabin crew members in addition to the minimum number of cabin crew and additional
crew members should be considered as passengers for the purpose of supplemental
oxygen supply.
CAT.IDE.A.235(b)(1) GM1 Supplemental oxygen — pressurised aeroplanes
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