Losing GPS a few minutes into flight - On multiple flights

[SackboyDad]

So I got my replacement Mavic after the first was replaced by DJI because of a defective gimbal.

I have flown it exactly 4 times since it arrived last Friday. Three out of the four times the aircraft has lost GPS and gone into ATTI mode about two minutes into flight. Each time the outage lasted a couple of minutes.

Twice it was in the suburbs of Columbus, GA and today it happened again smack in the middle of downtown Atlanta.

What is going on with these Mavics!?!?!?! The first one with the gimbal failure was annoying. This is totally unsafe! The first two GPS losses were in the country and totally and unobstructed skies. Absolutely no reason for GPS loss. I flew a third time (at dusk no less) with absolutely no issues for over 20 minutes. Never had a chance to fly again in Columbus because of rain.

Today in Atlanta I thought for sure I was going to crash - possible into a building. The aircraft started to drift and pitch while flying. Finally -- FINALLY you could see change to IN FLIGHT (No GPS) then go back to ATTI mode and do it again. Finally it went back to GPS and it stopped drifting and pitching.

Each time this has happened there have been full "bars" (for lack of a better term) on the display for GPS and have the "Ready to Fly (GPS)" green display. Stayed that way for a while until the loss of GPS....

I guess I need to send it back AGAIN as defective?!?!? Why is it doing this?


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[f3honda4me]

I would contact DJI. From what I have seen of others that had something similar, it was hardware related and had to be sent for repair.

 

[SackboyDad]

Can't DJI make a drone what actually works? First a defective gimbal now this? I'd really like to be able to actually use my $1299 drone and not have DJI just keep my money while it keeps going back to the repair shop over and over


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[CactusJackSlade]

Can't DJI make a drone what actually works? First a defective gimbal now this? I'd really like to be able to actually use my $1299 drone and not have DJI just keep my money while it keeps going back to the repair shop over and over


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They are capable of making good ones yes... but unfortunately seems like you got a "Friday afternoon" production one... it just happens sometimes. I got lucky, mine has had zero issues thus far, however my brother who received his the same day as I did (but from a different vendor) has the blurry right side issue... luck of the draw I guess.

Not making excuses for DJI (they have pissed me off in the past before as well) just sometime siht happens. - sorry for your frustration we've all felt it at one time or another if you'd been with DJI for any length of time!

 

[niclariv]

I'm sure you already thought of this, but just in case - you've updated the firmware right? Many people were experiencing an issue like that on earlier firmware (in November or so)


iPhone 6S

 

[Tok Pilot]

I am having the same problem, I take off with 17 satellites and within minutes it's drifting and says "ATTI MODE" no GPS, fly with caution. It doesn't last very long but still can't trust this thing. I played it back in the flight record function of the DJI GO 4 app and it show exactly when and where. Hopefully I can send these to DJI so they can see for themselves. Can I download these from the SD card? I have several Garmin hiking GPS's and all of them will get enough satellites while sitting on my couch through my big picture windows to navigate ,but not the MP. Either the GPS isn't near as good or there's a problem with the GPS in my MP. There's no reason for it to lose satellites flying above the trees. This never happens with my Garmins. I recently updated the firmware a few days ago and recalibrated the IMU, so that's not the issue. It was doing it before and after the update.

 

[Mako79]

If the MAVIC is stating GPS numbers but it decides switch to ATTI then you are experiencing compass issues. The compass is going skitz and the MAVIC is trying to fly away. The redundancy system is kicking in and switching to ATTI to prevent the flyaway. This is happening because many still believe in calibrating compass at EVERY flight location. This can cause flyaways as the compass snapshot can be wrong (magnet influences in large structures etc).

The fix is simple. Calibrate the compass in an open grassy field and do this ONLY ONCE!!!. This should get a clean-primed compass snapshot. Then travel back to your flight location and take off from a patch of grass or cardboard box (some roads/walkways may have rebar in the concrete).

 

[Tok Pilot]

Will it give a "weak GPS Signal" if you are experiencing a compass problem?


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[Tok Pilot]

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[Anthony]

How on earth can you have a weak gps signal when the drone is seeing 20 plus drones ?? I would be returning this to dji as that cant be normal.

 

[Antman305]

That's not normal.

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[erkme73]

Guys, this is a well documented issue. Are you on the most recent firmware? You're likely getting strong interference to your rear compass under full forward right stick. I'll post a link when I get to my pc. The latest firmware has the flight controller shifting from the noisy rear compass to the front so the compass data and GPS data dont deviate.

Mine was one of the first documented cases. I will be getting it back on Wed.

 

[erkme73]

Read this http://mavicpilots.com/threads/sudden-gps-loss-wide-drift-on-rth.1759

That first one is a teaser. Here's the real meat of the problem: Spooky Action at a Distance

It's along read, but thanks to @BudWalker's analytical skills, the problem is with the rear compass shielding, and not the GPS.

Once the compass gets overwhelmed by the magnetic interference of the high motor loads, the GPS and compass no longer agree. The flight controller would dismiss the GPS data and switch to ATTI mode.

See if you find any correlation between the GPS dropout and aggressive full stick forward flying. Above all, make sure you're on the most current firmware, as that will prevent the switching from GPS to ATTI.

 

[Anthony]

So is this something dji are looking to replace ??

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[erkme73]

I don't know what their long-term goal is. But if you have the symptoms I described (and those outlined in the links I provided above), I would strongly suggest you contact DJI support and let them know. If you are on the latest firmware, you would be seeing a bunch of warnings that read "Strong magnetic interference! Fly carefully" or something to that effect. The fix in the latest firmware not only switches the flight controller to the front compass, but it also produces that warning for the operator.

 

[Tok Pilot]

This is a screenshot of the firmware I was on at the time

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[erkme73]

Interesting. There may be more to this story than what I suspect. @BudWalker may be interested in getting a copy of your DAT file (located on the MP). This post will ping him.

 

[Tok Pilot]

I did report this to DJI support a few days ago but haven't received a reply. I am going to experiment some more and calibrate the compass in a large clearing without metal or electrical interference, also will try going full right stick and see if it does it again once it warms up outside (-15F today). I've always been able to take manual control in sport mode, which I assume is what's supposed to happen since it isn't relying on GPS except to hover, and fly it wherever I want.

What's the procedure for getting the DAT file for emailing it? I haven't connected my MP to a desktop computer yet, I'm assuming it's in a folder on the micro SD?


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[Tok Pilot]

Here are 2 others messages that popped up on the first and 2nd flights shown above, it also gave me a high wind warning on one of the flights where it didn't lose GPS, and it wasn't even breezy.

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[Tok Pilot]

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