Flying at Low Altitude After Diving

[Leroy Mercer]

I plan to be on the island of St. Maarten (SXM) in the coming days, and planning on doing some diving on the island. My wife has had St. Eustatius (EUX) on her bucket list for years now and wanted to go dive the wrecks on the island. The problem is getting back and forth between the two island. The main mode of transportation is by low altitude (below 3000 feet), non pressurized flights. A local dive shop says that we will be safe and will just need to mention to the pilot that we had been diving that day. I just want to be safe and stay as far way from DCS as possible. What should we do.

 

[Altamira]

This question has been asked numerous time on this board, and you will get a variety of answers depending on the responders' risk tolerance and, in many cases, lack of understanding as to the multitude of aircraft emergencies and problems that can induce the pilot to climb well above the "scheduled" aircraft altitude. Everything in aviation does not go as planned. Just remember, you are a passenger, and the pilot is responsible for the safe operation of the aircraft. Sometimes your needs are going to be secondary to the pilot's decisions and need to get the airplane safely on the ground. If it comes to a choice between doing everything possible to save the airplane and the passengers lives, or keeping you from getting bent, I can tell you with certainty what the pilot is going to choose.

 

[flyboy08]

How long is the flight? Flying at 3K shouldn't pose any issues unless you hit your NDL while diving...dive shallower and I dont see any issues. This plane is most likely not a pressurized aircraft either.

 

[JohnnyC]

I’d do it, aware of the fact that I might possibly be screwed if we had to climb to altitude.

That being said, a non-pressurized aircraft has altitude limitations, and if I were doing recreational dives I would be comfortable with the risk.

I would not be comfortable taking a regular commercial flight anywhere. Rapid decompression at 36,000 feet is bad enough without turning into an over cooked pretzel.

Now understand that there are a myriad of factors at play in every facet of this, and it’s easy to understand the recommendation to simply not fly after diving. And as such, despite saying I would be comfortable doing what you describe, I still wouldn’t do it, because I cannot guarantee there isn’t some variable I’ve completely missed.

 

[Thomas Ciampi]

I remember reading an article out of the DAN magazine that asked the same question. DAN said that there isn't enough data to provide a solid safe answer. They say to be conservative and not fly.


A link to the full article and magazine is here (page 60 on the PDF and 58 on the magazine)
https://d35gjurzz1vdcl.cloudfront.n...sets/common/downloads/AlertDiver_Fall2013.pdf

 

[luscioman]

Looks like there is a ferry

https://www.greatbayferry.com/day-trip

 

[broncobowsher]

My drive home after diving in the ocean involves driving over a mountain pass over 4,000'
Honestly not worried about it. It's not like you are getting out of the water on the edge of decompression limits and stepping into a waiting aircraft, unless that is your plan then you are doomed.
I've pulled up the tissue loading graph on the computer and watched it. By the time I am out of the water and made it back to shore, there is already a fairly good surface interval. Offgassing all that time. I add a cushion by spending a little extra time picking up a meal for the road, make it someplace sit down to take a little longer. I am plenty comfortable with my safety cushion. I do have it a little better, the drive over the mountain pass takes time as well, and it is a gradual ascent.

As for an aircraft at 3000', in general each 1000' of elevation is about ½PSI of ambient pressure, about the same as 1' of water (It's non-linear at higher elevations but for sub 10,000' elevation close enough). Your time on the surface is a giant safety stop before the last 3' ascent. Think that at 3000' you are at 90% of the air pressure you have at sea level.

For pressurized aircraft flying at 30,000 feet, the outside air pressure is closer to 300mBar. About 30% of sea level. That is a drastic pressure drop and something to worry about.

By some one rule fits all situations reasoning, it is wrong to fly. But if you look at what is involved you can make intelligent decisions.