Which emergency may require use of the Manual Release Tool (MRT)?

• A. Oxygen masks fail to deploy during a decompression
• B. Fire in the galley
• C. Loss of cabin pressurization
• D. Passenger medical emergency

Answer: (A)

When cabin oxygen is required, the masks normally deploy automatically from the overhead panels, but faults can occur and the masks may not release on their own. The Manual Release Tool is kept as a backup device that crew can use to manually trigger the release of the oxygen system so passengers can breathe in a decompression or other loss-of-oxygen scenario.

So, the emergency that may require the MRT is when oxygen masks fail to deploy during a decompression. The other situations involve different responses (fire suppression, handling medical issues) and do not rely on manually releasing the oxygen masks.