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Negative Altitude MA2

wallyballs

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I searched the forum, but didn't find anyone having the same issue Im having. If someone else can find it please point me the right direction..

The longer I fly the more negative my altitude reads, from the same point I took of from. I have see as much as -16'. RTH works fine. I have also noticed that when hovering it seems to not be very stable at times. ascending and descending slowly when about 5' from the ground. I have calibrated everything, IMU, sensors. I have made sure the firmware is up to date. I contacted DJI support via facebook and they should I should send it in for a repair. this drone is less than 3 weeks old with only 11 hours of flight time. i hate to think it needs to be repaired, seeing as it has never been crashed dropped and kept in a protected hard case. Is there anything else I should try before sending it off? Its really disappointing this is my 1st drone.. Thanks for any advise
 
The longer I fly the more negative my altitude reads, from the same point I took of from. I have see as much as -16'.. Is there anything else I should try before sending it off?
As the altitude readings come from a barometric sensor that measures air pressure, small differences are normal over the time of a flight.
Recalibrating the IMU might help reduce the amount of variation you are seeing.
 
As the altitude readings come from a barometric sensor that measures air pressure, small differences are normal over the time of a flight.
Recalibrating the IMU might help reduce the amount of variation you are seeing.
I wonder what changed for it to start doing this? I have calibrated the IMU..My biggest worry is that I cant trust my altitude reading.. Ive set RTH 20' higher..I just wonder how many others have this same problem...
 
I wonder what changed for it to start doing this? I have calibrated the IMU..My biggest worry is that I cant trust my altitude reading.. Ive set RTH 20' higher..I just wonder how many others have this same problem...
It's common and normal for the starting and finishing altitude to be a few feet out
 
It's common and normal for the starting and finishing altitude to be a few feet out
When I talked to DJI support via facebook they told me I should send it in for repair. That was actually the only advice they gave me.. I asked directly "is this common" the answer was "where are you located" ..I didnt file or request anything. Now I wonder if this is just a common issue and I dont send it in and it causes a problem will I get a reply that says "we asked you to send it in for repair"
 
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When I talked to DJI support via facebook they told me I should send it in for repair. That was actually the only advice they gave me.. I asked directly "is this common" the answer was "where are you located" ..I didnt file or request anything. Now I wonder if this is just a common issue and I dont send it in and it causes a problem will I get a reply that says "we asked you to send it in for repair"
Unfortunately DJI's help people are not a great source of helpful or accurate information.
Having a small difference in the height showing on your screen can't cause a problem.
It is common and I've given you advice to improve it.
 
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Unfortunately DJI's help people are not a great source of helpful or accurate information.
Having a small difference in the height showing on your screen can't cause a problem.
It is common and I've given you advice to improve it.
DJI help not being great is what I was implying. Im not sure 16 feet or just under 5 meters is a "small difference" . Unless the FAA considers 4% +/- acceptable at maximum height? If I'm right if I'm negative 16 feet on the ground, I'm positive 16 feet above maximum height. My experience in the past 5 years with both the FAA and NASA is that there are not tolerant with their restrictions.. I myself dont see it as a big deal, and if this is normal then Im good to go.. thanks for the help
I have calibrated everything, IMU, sensors.
 
Unless the FAA considers 4% +/- acceptable at maximum height?
And you only fly on a pancake flat prairie so that the height displayed on the app always shows the height your drone is above the ground?

I can't imagine the FAA ever caring if you were 400 ft +4%.
But I can't imagine a situation where they would be able to tell.
 
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DJI help not being great is what I was implying. Im not sure 16 feet or just under 5 meters is a "small difference" . Unless the FAA considers 4% +/- acceptable at maximum height? If I'm right if I'm negative 16 feet on the ground, I'm positive 16 feet above maximum height. My experience in the past 5 years with both the FAA and NASA is that there are not tolerant with their restrictions.. I myself dont see it as a big deal, and if this is normal then Im good to go.. thanks for the help

You are not imagining that the Mavic sensor suite is FAA-approved equipment, are you?
 
There is a common perception that there is more accuracy or precision available to the drone than there actually is. All measurement systems and their standards, have errors in them. The pilot in command’s responsibility is not to complain about them or blame DJI but to understand them and pilot accordingly.

GPS errors have the possibility of being as much as +- 16 feet from where you would expect. Altitude errors are to be expected due to the changes in atmospheric air pressure due to weather changes, air temperature, and the passage of time. Wind forecasts are not precise as they are theoretical, and not based on a specific time in a specific location. The 6 axis inertial guidance sensors have their own errors.
 
I searched the forum, but didn't find anyone having the same issue Im having. If someone else can find it please point me the right direction..

The longer I fly the more negative my altitude reads, from the same point I took of from. I have see as much as -16'. RTH works fine. I have also noticed that when hovering it seems to not be very stable at times. ascending and descending slowly when about 5' from the ground. I have calibrated everything, IMU, sensors. I have made sure the firmware is up to date. I contacted DJI support via facebook and they should I should send it in for a repair. this drone is less than 3 weeks old with only 11 hours of flight time. i hate to think it needs to be repaired, seeing as it has never been crashed dropped and kept in a protected hard case. Is there anything else I should try before sending it off? Its really disappointing this is my 1st drone.. Thanks for any advise
You are not imagining that the Mavic sensor suite is FAA-approved equipment, are you?

No I don't. I would assume the responsibility of the accuracy for any instrument or sensor falls on the pilot..
 
And you only fly on a pancake flat prairie so that the height displayed on the app always shows the height your drone is above the ground?

I can't imagine the FAA ever caring if you were 400 ft +4%.
But I can't imagine a situation where they would be able to tell.
On the gulf coast our height above sea level changes very little. Im 9 miles from the coast and only 30' above sea level. No mountains or even hills in my area. Being born and raised in the hills of Tennessee I sure do miss them.. I really don't see this as a problem either, but I really don't know.. It appears thats its not a big deal..
 
When I talked to DJI support via facebook they told me I should send it in for repair. That was actually the only advice they gave me.. I asked directly "is this common" the answer was "where are you located" ..I didnt file or request anything. Now I wonder if this is just a common issue and I dont send it in and it causes a problem will I get a reply that says "we asked you to send it in for repair"

If DJI is offering to repair your drone, I'd take them up on the offer. To me, it sounds like your barometer is defective, since your drone isn't even able to somewhat accurately display the AGL over a period of only a couple of minutes. Neither of my DJI drones have ever displayed data as inaccurately as what you are seeing.
 
You're going to have to decide on whats normal instead of relying on DJI support in this case. I agree with Meta 100%.
If the drone doesn't hold altitude in still air and climbs and descends more than a few inches something is wrong. Could be barometric change. I think a rapid change is around 18 ft in three hours. Don't hold me on that..I'm a dummy on weather.
I'm with Dawgpilot..you've been giving it a really good look and you're not comfortable with it...send it in while it only cost time.
 
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You're going to have to decide on whats normal instead of relying on DJI support in this case. I agree with Meta 100%.
If the drone doesn't hold altitude in still air and climbs and descends more than a few inches something is wrong. Could be barometric change. I think a rapid change is around 18 ft in three hours. Don't hold me on that..I'm a dummy on weather.
I'm with Dawgpilot..you've been giving it a really good look and you're not comfortable with it...send it in while it only cost time.
Thanks, after reading these replies and thinking about it. I'm going to send it back.
 
Thanks for all the great input. After reading these replies I've decided to send it back. Ill post an update once I get it back..

Is these any data I should collect before shipping it off?
 
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