If there is any conflicting information, your FCOM shall be the overriding reference.

Please read the footnote at the end of this page.

Q1. How many types of oxygen systems are there on A320 a/c?

A1.  The oxygen system consists of:

‐ A cockpit-fixed oxygen system, which supplies adequate breathing oxygen to the cockpit occupants in case of depressurization, or emission of smoke and noxious gases.

‐ A cabin-fixed oxygen system, which supplies oxygen for cabin occupants (passengers and cabin crew) in case of depressurization.

‐ A portable oxygen system, which is provided in both the cockpit and cabin and is to be used:

• As PROTECTION for the crew during on board emergencies.

• For FIRST AID purposes.

Q2. What is the main difference between the crew and the passenger oxygen system?

A2.  Crew is supplied from an oxygen cylinder, whereas the passengers are supplied by chemical oxygen generators.

Q3. What are the components of the crew oxygen system?

A3.  The cockpit’s fixed oxygen system consists of:

‐ A high-pressure cylinder, in the left-hand lower fuselage.

‐ A pressure regulator, connected directly to the cylinder that delivers oxygen, at a pressure suitable for users.

‐ Two overpressure safety systems to vent oxygen overboard, through a safety port, if the pressure gets too high.

‐ A supply solenoid valve that allows the crew to shut off the distribution system.

‐ Four full-face quick-donning masks, stowed in readily-accessible boxes adjacent to the crewmember’s seats (one at each seat).

– A flight crew smoke hood located on the right back side of the cockpit.

Stowage box for cockpit-crew O2 System:

Q4. What does yellow blinker indicate?

A4.  The yellow blinker indicates flow of Oxygen.

Q5. Yellow Blinker Flow meter is seen during cockpit preparation on the crew oxygen stowage box. What is its meaning?

A5.  This indicator flashes when oxygen is flowing.

Q6. What is tested, when you press RESET / TEST control slide to TEST position?

A6.  The crewmember presses the slide, and pushes it in the direction of the arrow to test:

–The operation of the blinker;

–The regulator supply;

–System sealing downstream of the valve; and

–The regulator sealing and system operation.

Q7. What is reset, when you press RESET / TEST control slide to RESET position?

A7.  Pressing the RESET control slide, after the oxygen mask has been used, cuts off the oxygen, and the mask microphone.

Q8. What does “OXY ON” Flag indicate?

A8.  As soon as the left flap door opens, the mask is supplied with oxygen and, once it closes (mask still supplied with oxygen), the “OXY ON” flag appears.

Q9. What is the meaning of N if N/100% selector is at “N” position?

A9.  With the selector at the ‘N’ position, the mask delivers a mixture of air and oxygen, the content of which varies with cabin altitude. When cabin altitude goes above 35 000 feet, the air inlet closes and the wearer breathes 100 % oxygen.

Q10. What happens when the mask is used with the N/100% selection at 100% position?

A10.  The mask delivers 100 % oxygen.

Q11. What is the meaning of 100% if N/100% selector is at “100%” position?

A11.  100% means that the wearer breathes 100% oxygen.

Q12. What is the function of EMERGENCY pressure selector?

A12.  Use of this selector creates on overpressure which eliminates condensation or fogging of the mask, and prevents smoke, smell or ashes from entering the mask.

Q13. What will happen when Emergency pressure selector is rotated in the direction of arrow?

A13.  Turning the knob, in the direction of the arrow, generates a permanent overpressure.

Q14. What is the purpose of the CREW SUPPLY push button?

A14.  This pushbutton controls the solenoid valve which when open, supplies low pressure oxygen to the masks.

Q15. If “CREW SUPPLY” p/b is OFF, what will be indicated on ECAM?

A15.  The CKPT OXY indication on DOOR/OXY page will turn Amber.

Q16. Is it true that by switching off Crew Supply, the oxy pressure is still available on DOOR/OXY Page?

A16.  Yes.

Q17. Where will you check the crew oxygen cylinder pressure?

A17.  On the ECAM DOOR page.

Q18. On which ECAM page could the flight crew check the exact pressure of the oxygen cylinder?

A18.  DOOR page.

Q19. When will OXY high pressure indication pulse in green? When will it turn Amber?

A19.  It pulses in green, when the pressure is < 800 PSI

Q20. In one of the preflight, you see OXY high pressure indication reading 900 psi and is covered by amber half frame. Is it ok? If on this flight you have three crew members on board, what extra check is required?

{If crew oxy pressure drops below 800 psi, what happens?}

{If crew oxy pressure drops below 400 psi, how is it indicated?}

A20.  When OXY high pressure is < 1500 psi, an amber half frame appears. To continue the flight, one would have to refer to ‘LIM-35 Cockpit Fixed Oxygen System’.

The OXY high pressure indication pulses in green, when the pressure is < 800 PSI.

The OXY high pressure indication turns Amber, when the pressure is < 400 PSI and CKPT OXY indication turns Amber.

Q21. When will REGUL LO PR indication appear on ECAM DOOR / OXY Page, in amber color?

A21.  It is in amber, if oxygen pressure on the low-pressure circuit is low (50 PSI).

Q22. In one of the flight, CKPT OXY indication on the ECAM Door/Oxy page has turned amber. What can be the reason?

A22.  It becomes amber, when:

‐ Pressure goes below 400 PSI

‐ Low oxygen pressure is detected

‐ The overhead panel’s OXYGEN CREW SUPPLY p/b is OFF.

Q23. What is indicated by a missing green thermal plug during an exterior preflight?

A23.  It indicates an oxygen system overpressure or thermal discharge.

Q24. What has happened if SYS ON light on OXY panel is illuminated?

A24.  This light comes on in white, when the control for the oxygen mask doors is activated.

Q25. What will happen if the guarded MASK MAN ON p/b is depressed?

A25.  The mask doors open.

Q26. At approximately what cabin altitude should the passenger oxygen masks drop?

A26.  The masks drop automatically when cabin pressure altitude exceeds 14 000 ft (+ 250, – 750 ft).

Q27. When does passenger oxygen flow start?

A27.  The generation of oxygen begins when the passenger pulls the mask towards the passenger seat.

Q28. How long the passenger oxygen will flow?

A28.  The mask receives pure oxygen under positive pressure for about 15 min, until the generator is exhausted.

Q29. What is the meaning of PBE? What is the duration of oxygen flow in PBE?

A29.  PBE stands for Protective Breathing Equipment. The duration of oxygen flow in PBE is 15 minutes.

Q30. What are the indications that the PBE oxygen supply has depleted

A30.  The hood collapses to the point that it touches your face or by a flashing red light in addition to the flashing green light.

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4 thoughts on “OXYGEN”

  1. A28) 13 min and 22 min options are also available.

  2. Syed Naqvi said:

    Good efforts for 320 team. Much appreciated. May I know any regulation exist regarding oxygen mask should be connected with portable bottle or not connected and secured sealed alongside bottle, in aircraft cabin during flight.

  3. Nice and clear. Thank you for the efforts.

  4. Abuali Aldubail said:

    nice , clear and very useful

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