What's the maximum no fly time?

[RainPilot]

No violations of any sort. It was, and still is. set to guage mode. I was using it to monitor run times whilst doing decompression diving.

Aha. In gauge mode, it does not have tissue information so defaults to a 48 hour fly time.

 

[CWK]

I have used mine in flight, I got PPO2 of 0.16 and 0.17

0.10 is too low for consciousness, hypoxia would be the result. I had clear tissues on mine, it was very interesting to see how the tissue graph loaded like crazy at first and then off gassed through the flight. Im waiting for an opportunity to take one that has been dived hard that day up and see what happens.

You are correct. I must have recalled incorrectly. It must have been 0.16 not 0.10. But we can still use N2 half tumes od the leading compartment to calculate no fly obligations.

 

[rongoodman]

Assuming that the slowest compartment is the leading compartment and is fully supersaturated after the last dive, the N2 half time of the slowest compartment may be used to determine the no fly before flying to 0.5ATA.

The slowest Buhlmann compartment has a 635 minute half-life. It's hard to imagine it being fully loaded on anything other than a saturation dive.

 

[CWK]

The slowest Buhlmann compartment has a 635 minute half-life. It's hard to imagine it being fully loaded on anything other than a saturation dive.

Yes. If we can trust Buhlmann to bring us safely up from 5ATA to 1ATA, surely we can use it to bring us safety to the cabin pressure inducated by PPO2 of 1.6 for 21%. The math suggests quite short no fly times. Alternatively, if you dive something like xx/50, you would not exceed m-value in a pressurised cabin even if you fly immediately after diving. But there is no harm keeping a no fly of 24 hrs.

 

[drbill]

I always give myself a minimum of 24 hours which should be more than adequate in your case. However if I'm on an extended trip doing a week or more of intense diving, I usually give myself at least 2-3 days at the end of the trip before flying (so I can enjoy the local culture as well).

 

[Lorenzoid]

Aha. In gauge mode, it does not have tissue information so defaults to a 48 hour fly time.

How potentially confusing, especially given how few people actually read the manual and would know that. I suppose Suunto assumes that most people who use Gauge Mode are more savvy than the average recreational diver and are capable of deciding independently of what the display shows how long to wait before flying. Still, it's a potentially confusing display.

 

[CWK]

I always give myself a minimum of 24 hours which should be more than adequate in your case. However if I'm on an extended trip doing a week or more of intense diving, I usually give myself at least 2-3 days at the end of the trip before flying (so I can enjoy the local culture as well).

I fully get where you are coming from and am in agreement with you. There are divers who are getting bent despite staying within NLD. The theoretical framework is far from perfect. Having said this, it does provide a useful frame of reference. For example, we can work out what if scenarios, just as we can plan for lost gas. What if war, disease or natural disaster dictates immediate air evacuation? I dive 40/70 and the ATA that corresponds to a PPO2 of 0.16 for 21% is 0.76. This suggests that I could get on a plane immediately without exceeding m-value. I’m not suggesting that anyone does this, but the theoretical framework does let us have a view about no fly.

 

[atdotde]

Indeed, if you just used the Buhlmann model to extrapolate to cabin pressure then no flight time would be much shorter (you should be ok after about 60-90min, try getting on board a plane so shortly after surfacing from a dive!) and not much longer taking into account loss of cabin pressure. But typical recommendations are much longer (24h for example). My suspicion is that that this is due to the tendency to err on the side of safety. Another aspect is that DCS symptoms can show up several hours after a dive. So, there needs to be no causal relation between DCS and flying, but even if you discover your symptoms while in the air makes proper treatment much more difficult. So the effect of making sure you don't get any symptoms could probably justify waiting a day before entering a plane.

 

[Neilwood]

I think the reason for the recommendations is not due to normal cabin pressure but the issues that would present in the requirement of an incident that suddenly de-pressurises the plane. If you have any residual nitrogen in your system at that point, you would potentially instantly become supersaturated.

Better to allow the 24hr IMHO just in case.

 

[Chris12day]

The real maximum time limit is if you take a decompression hit. The time is 48 hours after your last ride in the chamber. So, if you are on holiday. Take a DCS hit, you must re-book your flights for 48 hours after your last chamber ride has been completed. I understand this as being the maximum.