Atmos 2 starts to log dive (on the surface)

[notchinese]

Anybody have experience with this:

I was flying back from LC back to Grand Cayman on a small prop plane. While waiting for my flight back to the states, my Aeris Atmos 2 starts beeping at me as I have reached the 3 hour limit for the dive I was apparently on. It was showing a current depth of 7 feet while I was in the airport. I had absolutely no idea how to get it to abort the dive or reset it without deleting my previous 15 dives. I had stretched the internal memory to the max (by changing the sampling rate) and I would be p-ssed if I was going to lose 3 hours of dive data. The only thing I could do was to pull the battery (first time I had tried to do this), but about the time I pulled the clear plastic cover off, I looked and the computer had switched off.

Fortunately, it maintained all my dive info for download, so that was ok. Any idea why this happened? Only thing I could think of was the pressure drop on descent? The computer was already "on" from the SI from the previous AM, but the contacts wouldn't be "wet". Clues? Is it broken?

I guess the important thing would be how to get it to stop if it does it again. The function of the metal reset pin on the second button doesn't appear to be documented anywhere, but pressing/holding it did nothing. I saw how to do a hard reset, but it appears it wipes out all your data.

Sorry this is so long, thanks in advance for any assistance.

 

[fdog]

Uh-oh.

Take a look through this thread.

Good luck. From what you've said, it may be terminal, and they don't make them any more.


All the best, James

 

[spectrum]

Just being "on" could be a lot of salty contamination creating an activation path. The 7 foot depth is more dire. How briney was the unit at the time?

The activation is triggered by (water) conduction from the pin you noticed in the right hand button and one of the com port pins.

Be sure that this gets escalated to the manufacturer level. With your low dive count I'll assume it's a fairly new unit. Even though the model has closed out it's unlikely that the factory will not orphan your unit. A replacement upgrade to a current comparable model for little or no $$ is commonplace.

Pete

 

[notchinese]

James:
Thanks for the response and link. When I turned it back on to do the PC download - everything seemed to be OK.

Pete:
Thanks for clarifying the non-reset on the second button for me. I rinsed it in fresh water after my last dive and it was sitting out in the ambient air the rest of the day, so I don't know about the salt issue. I was assuming the 7 ft depth was due to the change in elevation from the puddle jumper flight. Anyway, I'll do the rinse thing per James' link. FYI: I bought it 2 1/2 years ago (I only do 1-2 trips a year) so I am out of warranty.

I'll send the question to Aeris to see what they have to say about it - I'll post response if I get one.

Thanks guys

Chris

 

[notchinese]

I heard back from Aeris. Paraphrasing, they said:
1. you can't turn the computer off manually (gee thanks)
2. I can send it back to them to get it checked out for only $110! (It cost about $250 brand new).

4 months out of warranty, like 30 dives on it and it breaks (maybe). If anyone out there has a relationship with someone at Aeris that I can plead my case to, I would appreciate it if you could pass their contact info along.

So the question is - do I pay for the "full service and calibration" - which I am guessing doesn't cover the cost of repair if indeed something is broken - or do I just buy another computer at this point? Or do I just write this off as an anomaly and continue to use the computer as if nothing happened?

Any advice would be appreciated.

Chris

 

[bperrybap]

I'd say there is a good possibility that there is nothing wrong with the computer.

Consider some rough calculations which should be good enough.

Planes tend to have cabin pressures equivalent to about 7-8 thousand feet.
The pressure at that altitude is about 10.8 to 11.6 PSI.
That corresponds to somewhere between 3 and 3.9 PSI change
from the ground of 14.7 PSI.
i.e. the pressure on the ground will be between 3 and 4 PSI higher than
the cabin pressure at altitude.

7 feet of water would be 7/33 ATM or .212 ATM or equivalent to (.21 * 14.7) PSI or 3.11 PSI
which is amazingly close to the pressure difference between what a plane
cabin at altitude would be and the ground where you saw the 7 ft dive depth.
Note: it might also be 7/32 ATM or .219 ATM or 3.22 PSI
(depends on if they swap to fresh water based on altitude)

It could be that the time to fly timer was not zero when the flight
started and perhaps their altitude sampling/adjusting algorithm got confused by
the flight. It could have been slowly setting its internal barometric pressure
base (surface atmospheric pressure) for its calculations to cabin pressure.

This could also happen if the computer accidentally was turned on by water
activation from some trapped water or accidentally pushing a button.
Upon activation the computer will set its surface pressure to the current
ambient pressure, which on a plane would be 8000 ft instead of 0 ft.

Then when the computer saw a change in cabin pressure it started a dive
because it saw enough equivalent pressure change to trigger the 3-4 ft water depth
trigger to start a dive.

The depth you saw on the ground sure seems to match the
pressure difference that would be expected for an altitude activated computer.

I'd go dive the computer in a pool somewhere and see if it seems to work ok.
If so, I'd write it off and continue to use it.

BTW, I think that when you send a computer in to Aeris/Oceanic they really
don't return your own back to you. They return an "equivalent" model. I've read some cases
where folks have sent in their older models and gotten a newer model back in return.
If you do decide to send it in. I'd get that clarified first.


--- bill

 

[H2Andy]

take the battery off for a few minutes (to be sure)

dive the computer again and check to see if it performs ok for a few dives

if it all works out, write it off to the Dive Goblins

 

[notchinese]

Bill - thanks for all the supporting calculations. I was thinking the same thing, except I didn't have the fancy math to back up my theory. The computer was not in a case, but just stuffed in the top of my daypack, which was in the cargo area of the plane. Maybe something was squishing the bag, which was, in turn, holding down the activation button. The pressure change part makes total sense.

Note to self - put the computer in a hard case of some sort!

Thanks for your advice, Andy. I need to replace the battery anyway, so I'll do that and rinse/clean it and see what happens. Damn Goblins!

Cheers guys and happy diving!

Chris

 

[Ber Rabbit]

Did you rinse it or actually soak it after the dive? We have Orca Pilots that will occasionally do their own diving on the surface (including ascent rate violations ) The best we can figure is the salt is the source of the problem so we soak them in fresh water between dives to dissolve any salt residue. I have a drybox I fill with water and we keep them in that.
Ber :lilbunny:

 

[fdog]

My Atmos2 follows the altitude. When driving home from Monterey (via Donner Summit, 7000') you can watch the variance in desaturation time. And activation at altitude, in a correctly functioning unit, should not show up as a a couple of feet underwater at sea level. At least it doesn't with ours; if turned on a Lake Tahoe, then driven down to sea level, they just show a reduced desat time.

I'd still think that there is a possible error with the pressure transducer.

The only way to tell for sure is when you go diving again. If it "gets stuck underwater" (thinks it's a couple feet underwater during a surface interval), is reporting incorrect depths while shallow, or otherwise behaves erratically, take Aeris up on the $110 offer - I did, and it was a like-new refurbished unit that has been perfect.

Or or save the $ to put toward a new one.



All the best, James