Page 387 - UK Air Operations Regulations (Consolidated) 201121

Part CAT - ANNEX IV - Commercial Air Transport Operations

QUICK DONNING MASKS
A quick donning mask is a type of mask that:
(a) can be placed on the face from its ready position, properly secured, sealed and supplying
oxygen upon demand, with one hand and within 5 seconds and will thereafter remain in
position, both hands being free;
(b) can be donned without disturbing eye glasses and without delaying the flight crew member
from proceeding with assigned emergency duties;
(c) once donned, does not prevent immediate communication between the flight crew
members and other crew members over the aircraft intercommunication system; and
(d) does not inhibit radio communications.
CAT.IDE.A.235(c) AMC1 Supplemental oxygen — pressurised aeroplanes
AEROPLANES WITHOUT AUTOMATIC DEPLOYABLE OXYGEN-DISPENSING UNITS
(a) For operations approved in accordance with Subpart L (SET-IMC) of Annex V (Part-SPA) to
Regulation (EU) No 965/2012 with aeroplanes first issued with an individual certificate of
airworthiness (CofA) after 8 November 1998, operated at pressure altitudes at or below 25
000 ft, and not fitted with automatic deployable oxygen-dispensing units, the flight crew
should manage the descent in case of a loss of power in order to ensure that the cabin
pressure altitude is not higher that 13 000 ft for more than 4 min.
(b) The operator should specify in the operations manual (OM) the aircraft capability in terms
of cabin pressure leak rate in case of engine power loss, as well as the relevant
procedures.
CAT.IDE.A.235(c) GM1 Supplemental oxygen — pressurised aeroplanes
AEROPLANES WITHOUT AUTOMATIC DEPLOYABLE OXYGEN-DISPENSING UNITS
For operations approved in accordance with Subpart L (SET-IMC) of Annex V (Part-SPA) to Regulation
(EU) No 965/2012, should a loss of engine power occur, it is required that sufficient supplemental
oxygen for all occupants is available to allow descent from the maximum certified cruising altitude,
performed at the best-range gliding speed and in the best gliding configuration, assuming the
maximum cabin pressure leak rate, during the entire flying time when the cabin pressure altitude
exceeds 13 000 ft.
In the case of pressurised aeroplanes first issued with an individual certificate of airworthiness (CofA)
after 8 November 1998, with a maximum certified cruising altitude above 25 000 ft, and not fitted with
automatically deployable oxygen-dispensing units, the amount of supplemental oxygen should be
based on a cruising altitude of 25 000 ft as CAT.IDE.A.235(c) limits the operations of such aeroplanes
to the aforementioned altitude.
For such single-engined turbine aeroplanes, with the energy source of the pressurisation system being
lost (this is at least the case of pressurisation systems relying on bleed air inflow), the cabin pressure
altitude increases at a rate dependent upon the pressurisation system design and the cabin pressure
leak rate.
Therefore, following an engine failure during such operations, the cabin pressure altitude will remain
below 13 000 ft for a certain duration, which should allow the flight crew to descend at the best gliding
speed during this period.
The intent of the CAT.IDE.A.235(c) requirement is to ensure that this does not result in any unsafe
conditions for the passengers, as the cabin pressure altitude might increase above 13 000 ft, as well
as not jeopardise the safety of operations approved in accordance with Subpart L (SET-IMC) of Annex
V (Part-SPA) to Regulation (EU) No 956/2012 by maximising the chances of reaching an appropriate
landing site.
CAT.IDE.A.235(e) AMC1 Supplemental oxygen — pressurised aeroplanes
AEROPLANES NOT CERTIFIED TO FLY ABOVE 25 000 ft
(a) With respect to CAT.IDE.A.235(e), the maximum altitude up to which an aeroplane can
operate without a passenger oxygen system being installed and capable of providing
oxygen to each cabin occupant, should be established using an emergency descent profile
that takes into account the following conditions:
(1) 17 seconds’ time delay for pilot’s recognition and reaction, including mask donning,
for trouble shooting and configuring the aeroplane for the emergency descent
(emergency descent data/charts established by the aeroplane manufacturer and
published in the aircraft flight manual (AFM), and/or the AFM should be used to
ensure uniform application of the option); and
(2) maximum operational speed (VMO) or the airspeed approved in the AFM for
emergency descent, (emergency descent data/charts established by the aeroplane
manufacturer and published in the AFM, and/or AFM should be used to ensure
uniform application of the option), whichever is the less;
(b) On routes where oxygen is necessary to be carried for 10 % of the passengers for the
flight time between 10 000 ft and 13 000 ft, the oxygen should be provided either by:
(1) a plug-in or drop-out oxygen system with sufficient outlets and dispensing units
uniformly distributed throughout the cabin so as to provide oxygen to each
passenger at his/her own discretion when seated on his/her assigned seat; or
(2) portable bottles, when a cabin crew member is required on board such flight.
CAT.IDE.A.240 Supplemental oxygen — non-pressurised aeroplanes
Non-pressurised aeroplanes operated at pressure altitudes above 10 000 ft shall be equipped with
supplemental oxygen equipment capable of storing and dispensing the oxygen supplies in accordance
with Table 1.

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