Which aircraft uses a gaseous emergency oxygen system?

• A. 737-700
• B. 737-800
• C. B787
• D. A320

Answer: (C)

The key idea is how emergency oxygen is supplied when cabin pressure is lost. There are two main methods: chemical oxygen generators that produce oxygen on demand in each mask, and a gaseous oxygen system that stores and delivers oxygen as a gas to the cabin.

The Boeing 787 uses a gaseous emergency oxygen system, supplying breathable oxygen from high‑pressure bottles distributed to the cabin. This approach contrasts with older generations (and the other aircraft listed) that rely on chemical oxygen generators in the passenger masks. The 787’s design avoids relying on chemical canisters in every mask and uses stored gas to provide the oxygen supply.