FAA Private Pilot Airplane (PAR)Aeromedical Factors and ADMMedium
A pilot plans to fly the day after scuba diving to a depth requiring a controlled ascent with a decompression stop. According to FAA guidance on flying after diving, how long should the pilot wait before flight to reduce the risk of decompression sickness?
- AAt least 4 hours
- BAt least 48 hours
- CAt least 12 hours
- DAt least 24 hours
Show answer & explanationAnswer & explanation
Correct answer: D. At least 24 hours
FAA guidance recommends waiting at least 24 hours after a dive requiring a decompression stop before flying, due to the higher risk of decompression sickness from residual nitrogen in the body at altitude.
Why the other options are wrong
- A. Four hours is far too short for any dive profile and would leave significant residual nitrogen.
- B. Forty-eight hours exceeds the FAA's stated recommendation, though longer is never unsafe.
- C. Twelve hours is the recommended wait for dives not requiring a decompression stop, not for dives that did require one.
Flying After Diving
Guidance to prevent decompression sickness from residual nitrogen expanding at altitude after scuba diving.
- No decompression stop required: wait at least 12 hours
- Decompression stop required: wait at least 24 hours
- Altitude reduces ambient pressure, allowing nitrogen bubbles to form
Memory trick: No stop, 12; Deco stop, 24 — wait it out before you fly