Altitude Inaccurate - off by 200 to 500 feet

I was excited to receive my new Dekunu One a week ago. I had previously set up my cloud profile, to include the designation of my home drop zone. I followed the instructions and connected the unit to WiFi and activated it. Everything seemed to be working…until I made my first two jumps with it on Saturday. The L & B audible I use in my helmet curiously sounded its programmed 1,000 ft canopy alert while my Dekunu One read just a bit under 1,500 ft. My next programmed audible alert for 600 ft. sounded as the Dekunu read in the 900’s. And the 300 ft. programmed audible alert came when the Dekunu read 550 ft. Once I was on the ground, my audible correctly read 0 ft., while the Dekunu showed that I was still 207 ft. up in the air.

I tried to explore the functions of the Dekunu more deeply prior to the next jump. I could not find any functions that manually recalibrated altitude, so I used the altitude offset, and set the Dekunu to read that the landing area was 200 ft. Lower in altitude than the takeoff area. (the altitude for our entire DZ is the same, including the buildings, runway, and landing area.) I also ensured that I was using ‘Feet’ and not ‘Meters’ as the unit of altitude measurement.

The next jump, I experienced the same concerning inaccuracy. Even with the altitude offset on the Dekunu by -200 ft, when I was actually at roughly 500 ft, the Dekunu read over 900 ft.

I own three altimeters, including the Dekunu. All three are digital, and fully functioning, and have never had a similar issue, at my home drop zone, or anywhere else.

Am I missing something? Is this unit defective?
We have a member of our drop zone who is from Australia, who got one of these in New Zealand when they were relatively new. He told me he has never had this problem, but also didn’t have any idea how to remedy it. We have another member of our drop zone who also just received her Dekunu, and I’m told she had the same issue.

Nebraska, U.S.

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Joe, i had the same issue and Suuport took care of me - they are doing great on their promise.
I had exactly the same iussue, between 200-500 feet off to my N3 and audible.


Sorry for my bad English! In my opinion, this is a problem of taking into account the place of droping. The Dekunu takes altitude well into account and there is, in my opinion, no danger. However, the Dekunu cloud takes into account the exact altitude of the drop point above the sea. I intended to make a post on this subject because I noticed this problem for a long time. I think this is a point not considered by computer programmers. But as I said, there is no danger.

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I had the same issue a few months back. My Dekunu lagged when climbing to altitude and was then 400ft off that entire skydive. Did a restart once I landed and it seemed to fix the problem. Doesn’t keep me from double checking it with my fiance’s Dekunu on each ride though. Every now and then it’ll be 50ft off from his, way more tolerable than 400ft though. Scary to have read 0ft before I was even on final! Still love this Alti forever!

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I have the same problem… but in other side : Dekunu show “0”… more that 100 meter before real landing… in fact the Dekunu One start (during the fly) very late, with 100 meter less than my Ares (and other skydiver altimeter in the plane)… I restart the device before the next jump and it is ok… I think it’s a software bug because I never have this problem before…


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Just a quick word on this, @JoeMama’s issue is isolated, if anyone else thinks they have a problem please email so that we can investigate for you.
Also some info in this thread may enlighten some people :slight_smile: Device altitude accuracy at various points

I hadn’t really noticed until this last week on an eval jump for my coach rating both instructors said I was breaking and pulling too low, when I KNOW I was right on the dot, and confirmed with video. Turns out that my One was reading almost 1000’ off. So the next time I jumped (and after the unit had been powered off, and charged) I had my analog and as far as I can tell the two were in lock step all the way up, and all the way down. Is it possible the unit flakes out at times, or is it something with GPS, or that we can’t use high accuracy GPS in the states? I was concerned at first, but then when it was right on with my analog (and audible), I assume it was a one time deal or something…? Is the offset function to be used in this case? I was previously thinking that was more for a difference in altitude from where you take off and land. Last, is there a link handy to the user manual, heaven forbid I actually do that and get a better idea if it’s a setting or operating issue I am missing or doing wrong.

@jpeery Thanks for taking the time to post, this is odd, I would like to investigate, I’ll send you an email so we can collect some info and logs

I don’t think I ever received an email, but don’t bother, I picked up an Atlas and I’m not using the Dekunu any longer.

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@jpeery I did email you immediately after posting a response, I will forward the email again.