What is a slow decompression?

• A. Sudden loss of cabin pressure
• B. Gradual loss of cabin pressure taking more than 10 seconds to equalize
• C. Equivalent to rapid but slower
• D. No change in cabin pressure

Answer: (B)

Slow decompression is a gradual loss of cabin pressure, where the pressure inside the aircraft falls slowly and takes more than about 10 seconds to equalize with the outside air. This slower rate means the cabin altitude rises gradually rather than instantly, so the change is less abrupt and there isn’t the quick, explosive feel of a rapid decompression. The time-to-equalize criterion (more than 10 seconds) is what distinguishes slow decompression from rapid decompression. The other options describe either a sudden loss, no change, or an undefined comparison, which don’t match this gradual, longer-than-10-seconds behavior.