Perdix Starts Dive During Flight

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CrumhornDiver

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Location
Ft. Lauderdale
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I was using my surface interval on a 3 hour flight from Bangkok to Manila to log dives from my Shearwater. I used it for about an hour. After I finished, I was in the main menu and was going to change the time when it started logging a dive!

I figured this must have had to do with a change in cabin pressure and would stop either as we descended or when the plane depressurized upon arrival.

I presently stand at baggage claim and the Dive is still going. My surface interval before I turned it on was more than 4 days. I have an Oceanic Geo 2.0 as well and it did not log a dive.

Anyone know what’s going on?

Did I accidentally manually trigger a Dive somehow?

Do I need to worry about the sensor or should I just remove the battery to reset it?

I searched Scubaboard and Google but could not find anything specifically about this.

Any guidance is appreciated.

Update: I unscrewed the battery compartment s but and it reset. The dive is logged there and the barometric pressure seems correct. I’m still a bit hesitant to rely on it for a dive until someone provides a plausible explanation of what happened.
 
Last edited:
Isn't the dive initiated with a humidity sensor? So you both triggered it and the pressure... maybe sweat (much sweat!) hands? Or maybe condensation inside the cabin.
 
If it registers an increase in pressure over what it assumes is surface pressure, it will initiate a dive. ( @npole the Perdix does not have wet switches ). Once the "dive" started, the computer is waiting for the pressure to reduce to the "surface" pressure where it started so it will continue to "dive" until such time, or when you reset it.

This is a common thing with computers, friends of mine have had a Suunto alarming non-stop after a flight and had to drop it in the toilet to get it to shut up. At least the SW have a reset ability with a battery removal.

I would use it no problem after the reset.
 
Thanks, @RainPilot. I think that makes sense.

@npole, my hands were not sweaty or moist at the time. However, as @RainPilot pointed out, there apparently is no humidity sensor.
 
I turned mine on during a flight. It immediately sensed the change in cabin pressure and started acting strangely as if it was on a dive when we descended. It remained pressurized after the flight until I removed the battery. Since then, I have not turned it on.
 
So, how does one avoid any such activation with certainty, especially on the flight to the dive trip, especially with a Suunto (especially if there is no way to reset..?
 
Hi Crumhorndiver,

If the Perdix is operating in the on-state inside an airplane, then it is possible for a false dive to start as the cabin pressure increases during descent. As you discovered, removing the battery is one way of breaking out of such a false dive. Newer firmware versions also have a menu option (End Dive) that allows breaking out of a dive when the absolute pressure is low enough. It sounds like there is nothing wrong with your Perdix.

npole - a dive will only start if the Perdix is turned on during the flight. If the Perdix is off, then a dive will not start on an airplane. The automatic wake-up requires an absolute pressure higher than would be encountered on an airplane.

We do have models with wet contacts, but we only include wet contacts when we deem them a safety feature such as on rebreather controllers. For non-rebreather controllers, we find that wet contacts are more of a nuisance than benefit. The only major drawback of not having the wet contacts is such false dives on an airplane. And while these can be surprising or somewhat concerning, they are not an indication of a malfunction.

Best regards,
Tyler
Shearwater Research
 
So, how does one avoid any such activation with certainty, especially on the flight to the dive trip, especially with a Suunto (especially if there is no way to reset..?
If there is a way to turn the auto-on function off, that would be a good start.
 
https://www.shearwater.com/products/peregrine/

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