Hi,  I have been flying my MA for a couple of months now with few issues.  when the new software 0.400 cameout about 2 months ago i blindly updated to it.  On my first flight inoticed some drifting but nothing that was not controlable and i have flown it many times since then.

this past Sunday I flew and was headed from my house to the Atlantic Ocean, about 1 mile.  Everything was good until about 3600 feet away when it switched into ATTI mode even though the flight log says there were 15 satellityed.  The gimbal started gyrating up and down and it took me a few seconds to get control of it and finally bring it home.

is there somewhere that I can upload the flight log for someone to evaluate?  

Yes, you can upload the flight data here: http://www.phantomhelp.com/LogViewer/Upload/

Upload your flight log to link as per Ken Storm post number 2. Then copy the URL for the results page to this thread and somebody may be able to give you an idea (or not) of what happened during that flight.

Thanks Ken and Aardvark, I will do that.

http://www.phantomhelp.com/LogViewer/KRF2GLNOF38SFA7F00W7/

I noticed there is limited data shown in this analysis.  I copied the CSV file to Excel and noticed that during this time of IMU errors the gimbal was going thru many gyrations.

Dalford Posted at 2018-8-2 07:40
I noticed there is limited data shown in this analysis.  I copied the CSV file to Excel and noticed that during this time of IMU errors the gimbal was going thru many gyrations.

IMU encounters exceptional heading, this warning is usually as a result of magnetic interference, usually picked up from the ground you launched from.
Did you take off from concrete which could have contained rebar, close to steel structures ie electronic doors etc.
I will explain below what happens in these situations.

The best way I can explain this is. If you put your Aircraft on the ground in normal circumstances, start it up, then lift it up and turn it 90 degrees to the right both your compass heading and IMU will both move together 90 degrees and no problems.
If you put your Aircraft on the ground and there is magnetic interference only the heading of your compass will change, your aircraft will still take off. But when it clears magnetic interference compass will then move to correct heading which you would think was great. But No, what happens is IMU is then conflicted and confused because of this sudden movement by compass, so you receive IMU exceptional heading warning, your aircraft cannot deal with data conflict so decides to switch to Atti mode dropping gps in favour of compass simply because aircraft can fly without gps but not compass.

While I can’t be certain you picked up interference from the ground or surrounding area it is the most common cause.
I have seen many cases where people start their aircraft in or on their car in their house and then bring it outside so damage is already done and we will see exact same warnings and and reaction from aircraft.

We all should check our compass when we start our aircraft and maybe more of this could be avoided, you can do this by checking the compass values in your app also check small red triangle in the lower left corner of your telemetry, it should be on the same heading as your aircraft.

One last thing I will say is we must always try to land aircraft immediately when this occurs. If it is safe to do so.

Dalford Posted at 2018-8-2 07:40
I noticed there is limited data shown in this analysis.  I copied the CSV file to Excel and noticed that during this time of IMU errors the gimbal was going thru many gyrations.

Compass distances.

Natural and Artificial Magnetic Anomalies Warning
Note
The following information has not been objectively tested to determine it’s impact on a Drones compass accuracy in flight.
        1        Many things can distort the earth’s magnetic field in the area you are flying:
        •        Steel framed or reinforced concrete buildings, bridges and roadways, iron pipes and culverts, high power electric lines, heavy equipment, trucks and automobiles, steel tanks, electric motors and even computers.
        •        Flying between steel framed or reinforced high rise buildings will distort the magnetic field in addition to causing GPS multi-pathing.
        2        Safe distances for compass calibration
        •        6” (15 cm) minimum: Metal rim glasses, pen/pencil, metal watch band, pocket knife, metal zipper/buttons, belt buckle, batteries, binoculars, cell phone, keys, camera, camcorder, survey nails, metal tape measure.
        •        18” (50 cm) minimum: Clipboard, data collector, computer, GPS antenna, 2-way radio, hand gun, hatchet, cell phone case with magnetic closure.
        •        6 ft (2 m) minimum: Bicycle, fire hydrant, road signs, sewer cap or drain, steel pole, ATV, guy wire, magnets, chain-link fence, bar-wire fence, data collectors
that use a magnet to hold the stylus.
        •        15 ft (5 m) minimum: Electrical box, small car/truck, powerline, building with concrete & steel.
        •        30 ft (10 m) minimum: Large truck, metal building, heavy machinery.

Is this where you took off from, on grass between concrete walk area and reclining beach chair?



Have you taken off from that exact spot before without problems?

Home point recorded GPS coordiantes show concrete walk area to left as take off point.

Launch point according to lat long on csv log.

hallmark007 Posted at 2018-8-2 07:55
IMU encounters exceptional heading, this warning is usually as a result of magnetic interference, usually picked up from the ground you launched from.
Did you take off from concrete which could have contained rebar, close to steel structures ie electronic doors etc.
I will explain below what happens in these situations.

Thanks hallmark, I will check the compass next time.  I have taken off from this same spot on many, many flights without this issue.  I am placing my MA on the cover of my spa.  I don’t think there is any metal in there.

What is different is I had my MA carry case close (~3’).  Don’t know if that matters.  Thx for the reply

HedgeTrimmer Posted at 2018-8-2 08:28
Is this where you took off from, on grass between concrete walk area and reclining beach chair?

[view_image]

Yes, many times.  I actually take off from the cover of a spa/hot tub.

hallmark007 Posted at 2018-8-2 07:57
Compass distances.

Natural and Artificial Magnetic Anomalies Warning

Thanks again hallmark.  I’ve come up with a solution to compass calibration.  I’m going to strip down naked and take my kayak (plastic type material) out to the middle of the lake in my backyard and then do the calibration, lol.   

Just joking, thx for the input, very interesting

hallmark007 Posted at 2018-8-2 08:41
Launch point according to lat long on csv log.
[view_image]

Yes, but google pic is out of date.  There is a hot tub located there now...

Dalford Posted at 2018-8-2 08:43
Thanks hallmark, I will check the compass next time.  I have taken off from this same spot on many, many flights without this issue.  I am placing my MA on the cover of my spa.  I don’t think there is any metal in there.

What is different is I had my MA carry case close (~3’).  Don’t know if that matters.  Thx for the reply

It’s easy check the heading with triangle bottom left hand corner, but no harm double checking app , you should see compass values in green smaller green is better.

Dalford Posted at 2018-8-2 08:51
Yes, but google pic is out of date.  There is a hot tub located there now...

I like the idea of a hot tub. Incidentally gimbal moving while aircraft in Atti mode, would be similar to gimbal movement in sport mode so if moving forward it will drop down and right or left will also cause sudden movements in gimbal, it’s just the way gimbal is configured in Mavic Air. One thing I can tell you, as someone who owns and flies a Mavic Air, IMU exceptional or compass problems have absolutely nothing to do with .400 FW, and I don’t think you will see any others reporting as FW problems. Compass problems and the need to check are common in every dji drone from Spark to Matrice, so it’s important to always make sure you compass is in good shape.

You will understand it a bit more from this video.

Dalford Posted at 2018-8-2 08:45
Yes, many times.  I actually take off from the cover of a spa/hot tub.

Unless there is some hidden steel in cover, and you have been lucky enough before to miss steel with MA, not very likely there was compass interference.   Could be your MA's compass is off some what, and need calibrating.  

If none of calibrations help, then you may be another victim of Mavic Air's .0400 firmware update.
This is part that bothers me, ''gimbal started gyrating up and down'', I would have expected side to side, based on reports of YAWing.

Dalford Posted at 2018-8-2 08:51
Yes, but google pic is out of date.  There is a hot tub located there now...

You might want to warn Google not to update their Sat. maps while you are out nude kayaking to calibrate your MA's compass...

In your FlightLog file there is this entry (#2003 time 201.2 seconds):
''Satellite Positioning Off. Fly with caution; Other (8)''
That is with 13 Satellites and height of 187.7 feet.  
On same entry drone switches to ATTI mode.

Looks like your drone was near Shark Center and Civil Air Patrol buildings.  Nothing in area that looks like it would cause trouble.
Brief drop in battery voltage shortly after, which appears to be with increase in speed, and 180 to return home.

Here is a link to my Airdata flight record.  Much more data.   https://app.airdata.com/share/aTrKEF

GPS signal strength dropped from 5 to 0 for 13 seconds.  Even though GPS Count never goes below 12 Sats.
Might be worth driving over to area where problem occurred and seeing if there is any interference to Drone's GPS.