For surface interval greater than 7 minutes after omitted stop, if no chamber is available, what is the action?

• A. Return to depth of stop. Multiply stop times by 1.5
• B. Chamber available: Use surface decompression procedure
• C. Observe on surface for 2 hours
• D. Abort decompression and ascend

Answer: (A)

When a mandatory decompression stop is missed and you don’t have a chamber available, the safe approach is to treat the situation as a need to re-apportion decompression time. If the surface interval since that omitted stop is longer than a short threshold (in this context, more than 7 minutes), you re-enter the decompression plan by returning to the depth of the missed stop and applying a conservative correction: multiply the planned stop times by 1.5. This compensates for the extra inert gas loading that occurred during the surface interval and reduces the risk of decompression sickness.

Why this fits here: without a chamber, you can’t perform surface decompression procedures, so you rely on in-water corrections to the decompression schedule. Returning to the depth of the missed stop keeps you within a controlled environment for offgassing, and the 1.5x multiplier provides a conservative extension of the stop times to account for the missed stop.

Why the other options aren’t appropriate in this scenario: simply observing on the surface for an extended period doesn’t address the decompression obligation and residual inert gas; aborting decompression and ascending ignores the need to offgas safely and raises DCS risk; waiting at the surface for a fixed period (like two hours) isn’t a recognized corrective method when a missed stop has already occurred and you’re without a chamber.