Why does the emergency oxygen system activate during rapid decompression?

• A. To provide oxygen to passengers and crew
• B. To power the engines
• C. To purify cabin air
• D. To deploy life rafts

Answer: (A)

When rapid decompression occurs, the main danger is hypoxia from the sudden drop in breathable oxygen at altitude. The emergency oxygen system is designed to prevent that by delivering a concentrated oxygen supply to everyone on board. It activates automatically because cabin pressure/altitude sensors detect the rapid loss of pressure, triggering oxygen masks to deploy so passengers and crew can start breathing with sufficient oxygen right away. This keeps the body’s tissues, especially the brain, protected while the aircraft descends to a safer, lower altitude. It’s not about powering engines, purifying cabin air, or deploying liferafts—the system’s sole purpose is to provide immediate, reliable oxygen during the decompression.