[NOTE: Q1 and Q2 must be read together as they are closely related.]
Reference: Regulation (EU) No 965/2012 on Air Operations; Regulation (EC) No 1107/2006 on the right of disabled persons and persons with reduced mobility when travelling by air
Article 10 of Regulation (EC) No 1107/2006 establishes the rights of disabled persons and persons with reduced mobility when travelling by air. The Regulation also stipulates that air operators should provide assistance, including transportation of medical equipment subject to dangerous goods legislation. Article 4(3) of this Regulation requires an air carrier or its agent to make publicly available the safety requirements and relevant information on restrictions. Annex II to the Regulation stipulates that the relevant legislation on dangerous goods can be invoked to limit the transport of mobility equipment. For more information on Regulation 1107/2006, please refer to the Commission's interpretative guidelines on this regulation from 11.06.2012, which has been published on the Commission's website and can be accessed here.
Regulation (EU) No 965/2012 of 5 October 2012 on Air Operations (Air OPS Regulation) refers to Annex 18 of the Chicago Convention and the Technical Instructions for the Safe Transport of Dangerous Goods by air when relating to their carriage on board. For safety reasons, oxygen/air cylinders or bottles are considered dangerous goods and fall under Annex 18 of the Chicago Convention; therefore, the provisions under Part 8 of the ICAO Technical Instructions must be applied to passengers who intend to carry these items with them on board. Oxygen/air cylinders for medical use of no more than 5 kg gross weight and never containing liquid oxygen are allowed in checked and carry-on baggage or on the person, with approval of the operator. In addition, the operator must provide the pilot-in-command with written information on their number and location on board. The valves and regulators of oxygen bottles must be protected from damage which could cause inadvertent release of the contents. Under the ICAO Technical Instructions, spare oxygen cylinders of a similar size are also allowed to ensure an adequate supply for the duration of the journey. The operator's Operations Manual, which has been approved by the National Authority, will contain procedures on the use of oxygen bottles.
Nevertheless, for safety reasons, national authorities may decide to prohibit all oxygen bottles, irrespective of their size, from being carried on board by passengers. Where the national authorities allow oxygen bottles of less than 5 kg to be taken on board, it is still left to the discretion of the operator to accept them, also due to safety reasons (oxygen is highly flammable and it cannot be guaranteed that the bottles/valves have been maintained properly).
If passengers have special needs, they should request more information from the airline at the time of booking.