How many oxygen masks are in each PSU in the main cabin?

• A. Two
• B. Six
• C. Eight
• D. Four

Answer: (D)

The main idea here is how oxygen is distributed in the cabin and what one PSU is designed to serve. In the main cabin, each Passenger Service Unit holds four oxygen masks. This setup matches the typical seating around that unit—two seats on one side of the aisle and two on the other—so the four masks provide immediate access for the four passengers closest to that PSU. If there were fewer than four masks, some passengers near the unit wouldn’t have quick access; if there were more, it wouldn’t align with the actual seating area that the unit is intended to serve and would complicate packaging and deployment. Keep in mind there are multiple PSUs along the cabin, each supplying masks for the adjacent seats, so everyone has access as the oxygen system deploys.