This weekend I was checking out a pecan orchard in the middle of nowhere.I pushed the M3P to 500m AGL and 2Km distance in sport mode. Took some shots, played around, and brought the drone back advancing and descending at the same time.


By the time the drone was around 300m away from me, the altitude on the RC was 80m, whereas in reality it was close to 20, by the time I landed, the altitude on the RC was 54m at the moment I caught it with my hand. Just after the motors shut down, the altitude went back to 0.


I found this extremely odd and somewhat disturbing, as you can't trust the telemetry being correct. Had I been looking above the horizon in my way back, my M3P would have bitten the dust literally and figuratively.



Have any of you experienced this before?


BTW: I attached my flight records if anyone wants to take a gander.


https://www.phantomhelp.com/logviewer/251X552V3OOZ4VNLPKBD/

I cant use those logs, you really need to upload your flightlog to this address and paste the link it gives you here, please follow the instructions, any issues come back here and ask... http://phantomhelp.com/LogViewer/\

PS, Drone police hat on here
500m is quite a bit over the legal height limit for Mexico which is @120m (400ft) just in case you are not aware. There is a 100ft separation layer between the drones max 400ft and the manned aircraft @500ft.

Bashy Posted at 8-29 19:01
I cant use those logs, you really need to upload your flightlog to this address and paste the link it gives you here, please follow the instructions, any issues come back here and ask... http://phantomhelp.com/LogViewer/\

PS, Drone police hat on here

I thought the AirData export would work. In any case I followed your instructions and uploaded the log to phantom help.

https://www.phantomhelp.com/logviewer/251X552V3OOZ4VNLPKBD/

Bashy Posted at 8-29 19:01
I cant use those logs, you really need to upload your flightlog to this address and paste the link it gives you here, please follow the instructions, any issues come back here and ask... http://phantomhelp.com/LogViewer/\

PS, Drone police hat on here

For what it's worth I was flying farther than 200km from the nearest airport, far from commercial flight paths and close to fairly tall hills / mounds.

royeiror Posted at 8-29 19:51
I thought the AirData export would work. In any case I followed your instructions and uploaded the log to phantom help.

https://www.phantomhelp.com/logviewer/251X552V3OOZ4VNLPKBD/

Thanks, yeah, i can see the height difference at the end but other than that, i cannot see any explanation as to why, Perhaps Labroides or JJB* may be able to shed more light on the issue.

In reply to your other reply, FYI; its not just about commercial or even airports, there are private aircraft, there are also emergency services flights that can happen at any time and from/to anywhere and can be at any height, for obvious reasons, this is the reason why we are given the blanket 400ft (120m) height law. If you was a very short distance from a decent hill/mountain then there is some leaway there but that depends on the country as to what the law allows.

Here in the UK for example, we have to imagine that there is a 400ft string hanging off the drone and it is not allowed to leave the ground.  If its a structure,say a tall building, i think we are allowed 50m above it at no more than 50m away from it, its something like that, but i think that that is only commercial only, i.e. have to be insured commercially, again, might be wrong there too, so much to remember.

Anyhoo, i just wanted to make you aware, that's all, i ain't gonna nag, its not my place to. Hope ya get to the bottom of the issue at hand, i will follow this

Bashy Posted at 8-29 22:36
Thanks, yeah, i can see the height difference at the end but other than that, i cannot see any explanation as to why, Perhaps Labroides or JJB* may be able to shed more light on the issue.

In reply to your other reply, FYI; its not just about commercial or even airports, there are private aircraft, there are also emergency services flights that can happen at any time and from/to anywhere and can be at any height, for obvious reasons, this is the reason why we are given the blanket 400ft (120m) height law. If you was a very short distance from a decent hill/mountain then there is some leaway there but that depends on the country as to what the law allows.

Thanks, I do hope more info is shed on the issue.

The rule here is that same as the in the US, 120m above and 120m around the peak. There really is no air traffic above or around this area. No commercial, civil or otherwise. It literally is in the middle of nowhere.

What a weird issue…
I seldom use sport (use the drone more for footage) but when I do, I will remember to be careful.

But you apparently didn’t go just by the numbers, that’s good I guess.

Hannibal_ Posted at 8-30 00:11
What a weird issue…
I seldom use sport (use the drone more for footage) but when I do, I will remember to be careful.

The ground looked oddly close and moving too fast for flying at 80m, so I kind of had to grapple with the dissonance and accept the numbers were way off, then stop and take a good look around, get my bearings and come back home safely.

Hi,

It is 'normal' to see at the end of the flight a baro height indication wich is few meter off, or in the plus or in the minus.

In your flight offset = +53 meters!

Mayby because the baro sensor was 'badly' influenced by temperature due to the reached height of nearly 500 (1st climb) or 400 (2st climb) meters and after that a fairly fast descent. Don`t know the temperature at level ground and at 500 meters, but from cold to less cold has some effect on the sensor.

See my chart of your data, see that the baro height line is not a fluent line, not keeping height indication kind of linear with the steady down speed.Result of this = +53 meter.
Sport mode only relevant here bc rate of decsent is higher than in normal mode.
Check in another flight, not to 500 meters, how the baro height indication is functioning.

cheers
JJB

Recalibrate the IMU to see if that brings the height difference between launch and landing to a more acceptable level.

JJB* Posted at 8-30 03:24
Hi,

It is 'normal' to see at the end of the flight a baro height indication wich is few meter off, or in the plus or in the minus.
[Image]

Your assessment makes sense, differing climatic conditions and a quick descent. Could be the culprit.

Although this phenomenon is new to me specifically with the M3P, as I've been a Mavic Pro owner for the last 5 years and even with a modified descent speed (10m/s) I had never encountered such a massive altitude mismatch.

I feel like it's something I'll have to learn to live with, a quirk of the model. Something I'll have to learn to keep in the back of my mind whenever I fly up to such altitudes.

I'll comb through my past flight logs and corroborate if this is unique to the M3P.

EDIT: Found another instance with severe mismatch, this case it was close to 40m.

https://www.phantomhelp.com/logviewer/6LHEKLJ3J447JB3U40SL/

EDIT2: found a case where the mismatch is barely noticeable.
https://www.phantomhelp.com/logviewer/6LPYLU4MJCPQJJOD59C5/

EDIT 3: another 35m mismatch.
https://www.phantomhelp.com/logviewer/0ZBTZFY3XXK7X5JTJU7L/

Combing through my logs, I've found a Mini 2 flight with only less than 2m mismatch.

https://www.phantomhelp.com/logviewer/3AOTATYS8BKW9IIIU87A/

EDIT: another mini 2 log with barely 2m mismatch.
https://www.phantomhelp.com/logviewer/14E73IDY20Y228XPNXMH/

EDIT 2: I won't spam you with all my other flight logs, but I've found that my Mavic Pro never had a mismatch higher than 2m.
The Mini 2 neither, so mi guess is it's inherent to the M3P, hopefully not a hardware design issue, just something that could be fixed through a firmware update.

royeiror Posted at 8-30 07:26
Your assessment makes sense, differing climatic conditions and a quick descent. Could be the culprit.

Although this phenomenon is new to me specifically with the M3P, as I've been a Mavic Pro owner for the last 5 years and even with a modified descent speed (10m/s) I had never encountered such a massive altitude mismatch.

have not check the other logs, but mayby logs with less alt mismatch flown in other conditions.
Not all flights with the same temperatur differences and same air humidity.

I have not yet a mini3 pro so cannot test if this model shows more height variation start/landing.

cheers
JJB

JJB* Posted at 8-30 10:49
have not check the other logs, but mayby logs with less alt mismatch flown in other conditions.
Not all flights with the same temperatur differences and same air humidity.

Definitely impossible to have the same conditions, and I do believe it has something to do with that. What's interesting to me is that in my specific case because of lack of a bigger pool of test subjects that the Mini 3 Pro is the one that is  an outlier in my unscientific 3 subject test.