How many oxygen masks will drop in each seat group (PSU)?

The correct answer is based on the design and functionality of the Passenger Service Unit (PSU) in commercial aircraft. Each PSU typically serves a specific grouping of seats. The standard configuration in many aircraft is that the PSU will provide one oxygen mask for each seat within that group. However, in the case of a passenger cabin, it's common for two masks to be made available for each pair of seats (for example, when there are two seats next to each other).

This means if the seating arrangement allows room for more than just two passengers, the PSU is designed to ensure that every passenger has immediate access to an oxygen mask in the event of an emergency. In a standard setup, this provision leads to a total of three masks being available, which may cover more than just the sum of individual seats due to safety protocols and accessibility to masks for those who may need assistance.

Hence, in a typical aircraft configuration, three masks will drop for every seat group, ensuring safety and compliance with aviation regulations regarding passenger safety during emergency situations.