Page 1 of 1

Missing "No Fly" information

Posted: Thursday 2. March 2023, 09:15
by kos
Good morning forum.

Been recently diving to the depths of 40-50m, accumulating upto 20 mins of deco time and noticed that my OSTC Plus was not showing "No Fly" time.

Here is an example, I have dived to max of 41,3m wwith and average depth of 22,3m and the duration of the dive was 38:30. The dive computer shows Desaturation time of 35hrs and 10mins, but the "No fly" information is absent. I remember seeing it after couple of dives underneath the Desat time, but surely it can not be the case that I am ready to fly after such a dive.

Is it expected behaviour or am i missing something?

OSTC showing desaturation

Dive profile

thanks for your help.

Re: Missing "No Fly" information

Posted: Thursday 2. March 2023, 11:22
by gr3yw0lf

did you take a look in the manual?

you can check your settings in "Deco-Setup"->"Waiting Time"

If the setting there is set to "Flying" the OSTC should calculate further to the cabin pressure of the plane (it calculates to 0,6 bar).
but if you got a low ambient pressure at the surface (e.g. 850-900 hPa) the "No Fly" warning could be very short (maybe only just a few minutes) and after that time the warning is not shown anymore.
that does not mean it is save to fly!! please wait at least 12h!!
it just means that the saturation of the tissues at 0.6bar is not "critical" or "supersaturated" - calculated at your personal GF settings. so the quest for the holy grale is your personal GF setting. If the GF high is set to a high value (e.g. 95 or 100) your shallower deco stops are shorter, 'cause these settings allow you to get out of the water with a saturation of 95% or 100% in your tissues and it would also effect the "No Fly" calculation....

Re: Missing "No Fly" information

Posted: Thursday 2. March 2023, 12:28
by kos
Thanks, of course I did look at the manual and even done some research online.
It seems that this issue had been raised several times already, but mainly in relation to the calculation of the No Fly or the 1-2-3000m value, but not its absence.
I think from a UI perspective it would make sense to indicate that the no fly time is gone and it is "safe" to fly. rather then the value disappears completely leaving no warning and the user clueless at its current state. For me, it would be more informative, if it would say "No Fly: 0 mins" or "No Fly(1-2-3000m): Safe"

regarding my GF values, I was initially diving on the default 30/85, but having witnessed the death of one of the liveaboard guests from DCS last week in Chuuk, most of the divers switched to the more conservative 30/70 and were making extra 5-10 mins safety stops in addition to accumulated deco time. So taking that into an account and the fact that I've switched to 73% deco gas, might have contributed to the extremely fast clearance of the "No fly time"

Re: Missing "No Fly" information

Posted: Thursday 2. March 2023, 12:44
by gr3yw0lf
ah - you mean a no fly not calculated by tissues but like the other divecomputers that use a simple countdown clock (nothing else is that in real when the dc shows "16h no fly") - nope that does the OSTC not - and I dont think it is necessary for a thinking, educated diver ;)

ok - don't get me wrong, 'cause it is your own thing - but at the GF I would take the GF low a little higher than 30 - maybe 40 or 45. so you ar not in the danger at deeper dives that your GF low lets you stop too early/too deep and instead you are desaturating (what you think you do) you are saturating again - even at your (deep)stop

maybe helpfull

Re: Missing "No Fly" information

Posted: Thursday 2. March 2023, 13:26
by Ralph
Hi, just some side note: the no-fly time is not calculated with the set GF (neither high nor low) but with 100% i.e. pure B├╝hlmann. Else depending on GF set, no fly may happen to never been reached...

Re: Missing "No Fly" information

Posted: Thursday 2. March 2023, 13:45
by gr3yw0lf
hi ralph
thanks for the sidenote - makes sense

Re: Missing "No Fly" information

Posted: Thursday 25. May 2023, 14:24
by Sputnik
That is my opinion still a bug. If you remove the battery and reinsert the battery and the computer reboot, the no fly time shows up magical. There should be already a thread with that problem.

Here my dive computers on my current dive trip. The first picture i reinserted the battery already, a few minutes later the same on the second computer. Here you can see the difference. I used both computers without any difference. The small time difference is due to the built-in quartz, and therefore there are slight deviations if you do not synchronize the time frequently.