After oxygen is flowing, what should be done next?

• A. Assess cabin
• B. Power down systems
• C. Open air vents
• D. Return to cruising altitude

Answer: (A)

Assessing the cabin is the immediate priority once oxygen is flowing. When oxygen starts to circulate after a depressurization event, the crew needs a quick, accurate picture of what’s happening inside the cabin: how many passengers are using masks, who might need help (children, elderly, or anyone with mobility or medical needs), whether anyone is injured, and if there are hazards like smoke or loose debris. This quick assessment informs all subsequent actions—who to assist, how to communicate with passengers, and what steps to take next with the flight deck (such as coordinating a descent and securing the cabin).

Choosing to power down systems isn’t the next step because essential systems and crew actions must remain coordinated during an emergency. Opening air vents isn’t appropriate because altering the ventilation can affect pressure and airflow in ways that aren’t helpful during a decompression event. Returning to cruising altitude would be dangerous, as climbing back up would raise the cabin’s exposure to lower breathable air and delay the necessary descent to a safer altitude.