In the aircraft industry, several systems are designed to provide safety and comfort for crew and passengers while traveling. Oxygen gets rarified with altitude, so life support is a very important system
The cabin is pressurized in order to provide breathable air, but reaching a sea level pressure is not advisable since it would lead to a significant pressure differential between the aircraft exterior and the cabin interior. This difference could damage the aircraft structure.
Additionally, the cabin altitude is different from the flight altitude. In fact, the cabin altitude corresponds to the one reached according to the cabin pressure. Usually a commercial flight cruises at an altitude of 35,000 ft, but thanks to the pressurization system, the cabin altitude is around 6,000-8,000 ft. Indeed, the oxygen system provides breathable oxygen to the crew and passengers if any problem were to occur during the flight.
AIRCRAFT EMERGENCY OXYGEN SYSTEM:
In a normal situation, a bleed air system is used to provide fresh air throughout the flight duration. The air is hot and must be cooled and pressurized to make it breathable. In the event of an emergency, the plane is already equipped with oxygen systems which are linked to passengers and cabin crew through masks. In fact, there are two oxygen systems on board. One designed for the crew, and the second for the passengers.
If the cabin pressure drops making cabin altitude about 14,000 ft, the emergency system are be triggered. The emergency system provides oxygen to passengers for 15 to 20 minutes, and for the crew members for around 30 minutes. This is enough time for the aircraft to descend to a lower altitude and being the cabin altitude to a safe breathable level.
Here, the crew oxygen system schematic of the Boeing 737 class is shown in Figure 1.
The main challenges of oxygen equipment are:
- Fitting the dimensions of the plane
- Secure (no leakage for example)
- Responsive (to cabin pressure and cabin altitude)
- Easy for passengers to use the oxygen system through the deployed masks quickly, before the effects of altitude are felt:
- At 25,000 ft: a person has 3 minutes of consciousness
- At 41,000 ft: a person has 30 seconds of consciousness
FLIGHT CREW OXYGEN
The flight crew oxygen should be designed and made with a lot of care, because if any trouble occurs during the flight, the crew must be able to handle the situation and take the airplane and its passengers down safely. Read More