Supplemental Oxygen Requirements (Provision of oxygen)

USA : 12,500 feet
Australia : 10 000 feet
HK: flight level （FL) 100

USA

https://www.flyingmag.com/private-pilot-supplemental-oxygen-requirements/

91.211 Supplemental oxygen.

(a) General. No person may operate a civil aircraft of U.S. registry—

(1) At cabin pressure altitudes above 12,500 feet (MSL) up to and including 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen for that part of the flight at those altitudes that is of more than 30 minutes duration;

(2) At cabin pressure altitudes above 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen during the entire flight time at those altitudes; and

(3) At cabin pressure altitudes above 15,000 feet (MSL) unless each occupant of the aircraft is provided with supplemental oxygen.

https://www.faa.gov/pilots/safety/pilotsafetybrochures/media/oxygen_equipment.pdf

Australia

Civil Aviation Amendment Order (No. R3) 2004 – Civil Aviation Order 20.4 – Provision & use of oxygen & protective breathing equipment (02/12/2004)

i.e CAO 20.4

6 SUPPLEMENTAL OXYGEN REQUIREMENTS FOR UNPRESSURISED AIRCRAFT
Supplemental oxygen for flight crew members
6.1 A flight crew member who is on flight deck duty in an unpressurised aircraft must be provided with, and continuously use, supplemental oxygen at all times during which the aircraft flies above 10 000 feet altitude.
6.2 A flight crew member must, in respect of any period during which the member is not on flight deck duty, be provided with the amount of supplemental oxygen that is provided to a crew member in accordance with paragraph 6.3.
Supplemental oxygen for other crew members
6.3 A crew member (not being a flight crew member on flight deck duty) in an unpressurised aircraft must be provided with supplemental oxygen:
(a) in respect of any period exceeding 30 minutes during which the aircraft flies between 10 000 feet altitude and Flight Level 120 (both inclusive); and
(b) at all times during which the aircraft flies above Flight Level 120; and must use supplemental oxygen at all times during which the aircraft flies above Flight Level 140.
Supplemental oxygen for passengers
6.4 Where an unpressurised aircraft carrying passengers flies for more than 30 minutes above 10 000 feet altitude and up to and including Flight Level 140, the aircraft must carry sufficient supplemental oxygen to supply:
(a) 10% of the passengers with oxygen for 30 minutes; or (b) 20% of the passengers with oxygen for 15 minutes.
6.5 Where an unpressurised aircraft carrying passengers flies above Flight Level 140, the aircraft must carry sufficient supplemental oxygen to supply each passenger with oxygen during all periods that the aircraft flies above Flight Level 140.

Hong Kong (HK)

Cap448C Section 34

Public transport of passengers—duties of pilot in command

(g)

in the case of aircraft in respect of which a certificate of airworthiness was first issued (whether in Hong Kong or elsewhere) on or after 1st January 1989 except in a case where a pressure greater than 700 hectopascals is maintained in all passenger and crew compartments throughout the flight, take all reasonable steps to ensure that—

(i)

before the aircraft reaches flight level 100 the method of use of the oxygen provided in the aircraft in compliance with the requirements of Article 13 of this Order is demonstrated to all passengers;

(ii)

when flying above flight level 120 all passengers and members of the cabin crew are recommended to use oxygen; and

(iii)

during any period when the aircraft is flying above flight level 100 oxygen is used by all the flight crew of the aircraft;

(h)

in the case of aircraft in respect of which a certificate of airworthiness was first issued (whether in Hong Kong or elsewhere) prior to 1st January 1991, except in the case where a pressure greater than 700 hectopascals is maintained in all passenger and crew compartments throughout the flight, take all reasonable steps to ensure that—

(i)

before the aircraft reaches flight level 130 the method of use of the oxygen provided in the aircraft in compliance with the requirements of Article 13 of this Order is demonstrated to all passengers;

(ii)

when flying above flight level 130 all passengers and members of the cabin crew are recommended to use oxygen; and

(iii)

during any period when the aircraft is flying above level 100 oxygen is used by all the flight crew of the aircraft;

Provided that he need not comply with the provisions of this subparagraph (h) if he complies instead with the provisions of subparagraph (g) of this Article.