Which of the following can cause gradual decompression?

• A. Sudden loss of oxygen masks
• B. Cracked window; door leak; faulty seal around door/window; malfunction of aircraft pressurization system
• C. Engine failure
• D. Weather changes

Answer: (B)

Gradual decompression happens when the cabin slowly loses pressurization due to a small breach or a fault in the pressurization system, so the air escapes or isn’t replenished over time rather than in a single explosive event. A cracked window, a door leak, or a faulty seal around a door or window creates a slow, continuous path for air to escape, while a malfunction of the pressurization system means the system isn’t maintaining the intended cabin pressure, both leading to a gradual drop.

In contrast, a sudden loss of oxygen masks is a response to rapid (explosive) decompression, not a cause of gradual decompression. Engine failure by itself doesn’t necessarily cause a persistent cabin pressure loss, and weather changes don’t inherently create a gradual loss of cabin pressure either.