AS9120B, ISO 9001:2015, AND FAA AC 0056B ACCREDITED

What Is an Aircraft Oxygen System

When one rides on an aircraft, they trust that everything is in place to ensure safety during the duration of the flight. One critical component of aircraft safety when transporting passengers and crew is the presence of an efficient and reliable oxygen system. The aircraft oxygen system plays a vital role in maintaining the health and well-being of individuals at high altitudes where oxygen levels are significantly reduced. In this blog, we will explore the key aspects of a general aircraft oxygen system, discussing their main types, functions, and importance.

Common Types of Aircraft Oxygen Systems

  • Air Crew Oxygen System: The air crew oxygen system is a type that is specifically designed for flight crew members, providing them with a constant supply of breathable oxygen in the case that pressurization fails. This system consists of oxygen masks, regulators, flow indicators, and pressure relief valves. The masks provided by such systems are equipped with microphones to ensure clear communication, allowing pilots and crew members to effectively perform their duties even in oxygen-deficient environments.
  • Passenger Oxygen System: The passenger oxygen system is primarily intended for the safety of passengers during emergencies. In the event of a loss of cabin pressure, oxygen masks are automatically deployed from overhead compartments. These masks are connected to chemical oxygen generators which produce breathable air when activated. Once deployed and masks are equipped, passengers can breathe comfortably until the aircraft reaches a safe altitude or the issue is resolved.
  • Portable Oxygen System: Apart from fixed oxygen systems that are built into the cabin or airframe, aircraft are also equipped with portable oxygen systems. These portable systems consist of lightweight cylinders filled with compressed oxygen, and they are primarily used by cabin crew members to assist passengers who may require additional oxygen during the flight. The cabin crew can easily carry these portable systems to passengers in need, ensuring their well-being until they can receive further medical attention. This also allows for solutions on an individual basis as the wider passenger oxygen system deploys cabin-wide during emergencies.

Functions of an Aircraft Oxygen System

  • Supplementing Oxygen Supply: At high altitudes, atmospheric air becomes thinner, resulting in reduced oxygen levels. The primary function of the aircraft oxygen system is to supplement the natural air supply with a controlled flow of oxygen. This ensures that both the air crew and passengers receive adequate oxygen to breathe, preventing hypoxia and related health complications.
  • Maintaining Cabin Pressure: The cabin pressure control system in an aircraft ensures that the pressure inside the cabin remains at a comfortable level, similar to that experienced at lower altitudes. The oxygen system works in conjunction with this system to maintain the required pressure differential between the cabin and the outside environment. This prevents the risk of decompression sickness and allows occupants to breathe comfortably through a flight operation.
  • Emergency Situations: In the event of an emergency, such as a loss of cabin pressure or smoke being present in the cabin, the oxygen system plays a crucial role in ensuring the safety and well-being of everyone on board. The deployment of oxygen masks allows occupants to breathe normally and remain conscious, enabling them to respond to the emergency or follow evacuation procedures efficiently.

Cylinder Pressure and Maintenance

The various oxygen equipment in aircraft relies on compressed oxygen stored in cylinders for supply. These cylinders are pressurized to ensure an adequate and continuous oxygen supply when necessary, and cylinder pressure is carefully monitored and maintained within specific limits to guarantee its effectiveness during critical situations. Regular inspections and maintenance procedures are also conducted to ensure the integrity of all oxygen system assemblies. These procedures involve inspecting masks, regulators, valves, and tubing for any signs of damage or wear. Any faulty or expired components are replaced promptly to maintain the system's reliability.

Importance of the Aircraft Oxygen System

The aircraft oxygen system is of utmost importance for the safety of all occupants, especially during flights at high altitudes. This is a result of the system promoting emergency preparedness and enhancing overall passenger comfort. Hypoxia, which is caused by oxygen deficiency, can impair cognitive function, reduce alertness, and lead to loss of consciousness. The oxygen system ensures a sufficient supply of oxygen to prevent the onset of hypoxia, allowing the flight crew and passengers to remain alert and responsive during emergencies so that effective responses can be carried out.

Outside of emergency situations, passenger comfort is essential during air travel. The presence of an efficient and well-maintained oxygen system provides reassurance to passengers, knowing that the airline prioritizes their safety and health. Additionally, portable oxygen systems offer peace of mind to individuals with specific medical needs, ensuring a more pleasant and worry-free journey.


Overall, the aircraft oxygen system is a critical component that guarantees the well-being of passengers and aircrew members during flights. With its various components and functions, this system plays a vital role in preventing hypoxia, maintaining cabin pressure, and ensuring preparedness during emergencies. By prioritizing the maintenance and proper functioning of the oxygen system, airlines demonstrate their commitment to passenger safety and comfort. If you are in search of top-quality aircraft oxygen system parts and components that trace back to leading global manufacturers, look no further than Alpha Aerospace Parts.

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