When your computer gets stored in cargo bay at 30,000'

[Flutter]

My husband & I always pack our regs/computers with our carry-on to go inside the plane in the overhead bin. On our last trip to Cozumel, the last leg of our arrival flight was in a CRJ (Canada regional jet) & all passengers' luggage was stored in the cargo hold in the belly of the plane. This has happened before. This trip, however, we believe the jet's exterior low atmospheric pressure combined with the cold temps caused 1 of our computers to change its caliberation slightly from normal. While in Cozumel diving, the pressure gauges were both fine. The nitrogen/oxygen "loading" graphs also tracked on both computers, as did the NDT. So it wasn't until we compared computers at depth, side by side, that it became evident that one of our computers was Fluctuating from the other. . After monitoring the 2 side by side, we then checked with another diver to determine which computer's depth gauge was off.
We've had to check our computers/carry-on luggage in the cargo hold on several other trips, flying our last leg into Cozumel - no problem. And we've not heard of this happening, to other divers.
** But we wanted to give a HEADS UP to those of you who frequently fly in smaller planes, or dive alone, & might not occasionally or ever compare your computer to another diver's computer at various depth & catch such a sudden "apparently" unwarranted slight (but possibly significant) computer malfunction. We could have easily missed this fluctuating error & 1 of us unknowingly taken on more nitrogen/oxygen loading than we planned.
** We are in the process of purchasing 2 new computers (we like them to be the same, for comparison) and will cetainly be sure to grab our new computers out of our luggage before they whisk away our bags into the cargo hold in the future. Even if we have to stuff them into my "handbag".
** We serviced our gear & "pool dive" checked it a month before out trip, & everything was "go to go" then. (We compared depths at that time). Guess the lesson here is "trust your instruments" - but double-check them, to make sure they are actually functioning normally. (As far as I know, our lds can't check our computers' depth gauges at various depths to check them & then re-calibrate, if necesary, during maintenance). . .

 

[iamrushman]

thanks for the info and heads up....just by chance are your computers in a console or wrist mounted?

 

[gopbroek]

On all modern jet aircraft that I am aware of (Bombardier, Embraer, Boeing or Airbus) the cargo hold is within the same pressurized tube as the passenger area and is pressurized to the same level. The only difference is in the amount of conditioned air directed to those areas (temperature, not pressure level), I have seen the luggage compartment get cold at altitude but never have I seen it freezing. I have heard of, but never witnessed, issues of turning a computer on prior to or in flight and it sensing the lower ambient pressure of a cabin altitude in flight (typically around 8K’) and causing it subsequently think your are high altitude diving.

FYI, I am an aircraft mechanic

 

[dlofting]

I always dive with 2 computers, more for a backup if one fails completely.....but it also provides a way to see in any significant discrepancies exist. I`ve also fixed a number of home computer hardware or software problems over the years where I never knew the cause, so would be reluctant to ever rely on one computer, with no backup.

 

[TMHeimer]

Was the battery in the computer (and if it wasn't, would that make a difference?)?. Maybe the safest thing to do (if it's not a console) is to take it on the plane--they certainly allow a small personal bag (laptop bag, purse) on the plane with no extra cost...well, maybe...

 

[Flutter]

Thanks for the input. We have console units, but are looking at wrist units this time around. Our consoles were Suunto Gekkos (which always worked well for us). This time we are looking at Zoops (because we are familiar with the "set up") or something else reliable with Nitrox settings. Does anyone have other wrist computer brand suggestions? We dive Nitrox. Our batteries were in our computers and new. Good for the season.
Gopbroek, you may be right about the pressure in the cargo hold being at whatever the plane interior was at. After some thought, my husband agreed. If the computer somehow got bumped while in the cargo area (although it was totally surrounded by my clothing/soft items in my luggage), can anything be down to reset it?
Thanks.

 

[oldschoolto]

The aircrafts pressure hull is from about 3' from the nose to the rear bulkhead right before the tail tapper... As said before, its may not be "hot" but live animals are shipped in the cargo hold... I don't know what went wrong with your computer but its time in the cargo hold had nothing to do with it.....

Jim....

Pilot and one time aircraft owner and Mechanic...

 

[Flutter]

Oldschoolto, thanks for that. Now we can stop the "would have, should have, could haves" thoughts. It was maybe just time for replacement. We will mention it to our lds & if they don't have any repair ideas, just go forward. I was feeling pretty badly about not grabbing the computers out of our bags before they took them off.
I think we will still compare our computers' depth gauges on occasion, going forward, while diving, knowing now that such a computer issue can arise. I honestly hadn't heard of it happening to anyone before. Thanks for all your insight. Appreciate it.

 

[The Chairman]

How far off? Are we talking a foot or two or ten?

 

[ajtoady]

I am curious as to how much the variation was. I dive two identical computers and at about 100' they may vary as much as 2-3%. I very rarely push the limits and feel that that is an acceptable amount.