Hey guys, sad to report that my maybe three month old mavic air decided to go off on it's own today just after take off (1ft off ground) and wouldnt respond to inputs. I was flying it by my house and it just shot up to the right, tried to save it and give it full stick down but it just kept going up and towards the house. It smacked the side of the house and fell to its doom onto pavement

Ugh.

Not sure what happened,  but I looked at the screen and noticed it said compass calibration error, but it had solid GPS connection. Sucks. I could've swore compass was fine while lifting off.

It was in the air for maybe 9 seconds. Scuffed up pretty bad.

So just before this happened I was having lots of glitches in the DJI Go app and it was disconnecting and freezing while in flight just a few minutes earlier. I actually brought the mavic down for a battery change, uninstalled and reinstalled the app, rebooted my tablet and popped in a new battery to fly again, next lift off was when the crash happened. I've never had an issue with the DJI Go app, and it's a dedicated tablet for my controller, so it was odd. Has anyone had any issues on DJI Go since the last update?


I thought if it has a good GPS connection the drone won't fly away on you. But not if the compass has a calibration error. Anyone have any input?

Help if you could upload your last flight log to here http://www.phantomhelp.com/LogViewer/Upload/ then post link PhatomHelp returns.

I was flying it by my house and it just shot up to the right, tried to save it and give it full stick down but it just kept going up and towards the house.


Have you flown from that exact spot before?

Drone even with compass problem should respond to full stick down (aka land), and not continue going up.

HedgeTrimmer Posted at 2018-7-1 21:37
I was flying it by my house and it just shot up to the right, tried to save it and give it full stick down but it just kept going up and towards the house.

Yes fly this exact spot many times, this is my first flyaway but it wasn't in atti mode, I'll upload my logs as I just finished transferring them.

before this happened I was having lots of glitches in the DJI Go app and it was disconnecting and freezing while in flight just a few minutes earlier.
Has anyone had any issues on DJI Go since the last update?

There has been lag issues reported with DJI Go-4 app.  Looks like DJI has found a problem:
we couldn't repeat the issue of the transmission delay at our side, we had also provided some suggestions to the OP for troubleshooting, but the issue persists. Later, the engineers found out that it was about the DJI GO 4 app.  

http://www.phantomhelp.com/LogViewer/UYTZQR1LP9NPPHMCA6A3/

I feel so bad, it was very painful to watch and listen to. Such an expensive thing to crash.

Nick1 Posted at 2018-7-1 21:43
Yes fly this exact spot many times, this is my first flyaway but it wasn't in atti mode, I'll upload my logs as I just finished transferring them.

Being you did see "compass calibration error" after crash, and it sounds like not before - It is possible compass error is result of crash.  Flight logs will provide info as to when "compass calibration error" first occurred.

Reason I asked about exact spot, is there has been issues caused by sources of magnetic field interference when takeoff spot were things like concrete sidewalks, driveways, picnic tables, and boat piers - due to steel rebar or heavy gauge steel mesh panels embedded in concrete.  

Knowing exact spot, you can go back and check spot for magnetic field interference, using either Android or iOS device running one of several free to dirt cheap Apps that show magnetic fields using built-in XYZ axis sensors that are used by device for Compass.

HedgeTrimmer Posted at 2018-7-1 21:54
Being you did see "compass calibration error" after crash, and it sounds like not before - It is possible compass error is result of crash.  Flight logs will provide info as to when "compass calibration error" first occurred.

Reason I asked about exact spot, is there has been issues caused by sources of magnetic field interference when takeoff spot were things like concrete sidewalks, driveways, picnic tables, and boat piers - due to steel rebar or heavy gauge steel mesh panels embedded in concrete.  

Is there any way to read these logs other than the one you showed me? I'm curious too. It was concrete and it usually never has a compass issue there, but it does happen and I bet it's got rebar in it. I do fly from this spot very often but not *exactly* the same spot. Previous flight before I had to calibrate compass, and that worked fine. This time, I'm almost positive it did not have a compass issue at takeoff, but there's still that possibility. It happened so quick, caught me off guard as I just took off and went to hover a ft off the ground and it just went it's own way. What would be the best way to approach DJI with this? Through the DJI care or support?

This is spot on from that other thread, I was getting glitching just like this, app freezes and it crashed on me 2x.

Nick1 Posted at 2018-7-1 21:48
http://www.phantomhelp.com/LogViewer/UYTZQR1LP9NPPHMCA6A3/

FlightLog you uploaded does not show any "compass calibration error" or any compass warnings.

Drone started to takeoff at 6.8 seconds after power-up.  With 11 satellites.
At 7.0 seconds after power-up Home Point GPS coordinantes were recorded.

18.5 seconds after power-up, the FlightLog shows a motor obstructed error.  

21.0 seconds after power-up, it looks like drone was down.

HedgeTrimmer Posted at 2018-7-1 22:03
FlightLog you uploaded does not show any "compass calibration error" or any compass warnings.

Is that good news? I actually can't remember when I looked at the screen because it happened so fast I couldn't take my eyes off the drone. It may have been after it was down that I looked and saw that. Hmm.

Nick1 Posted at 2018-7-1 22:07
Is that good news? I actually can't remember when I looked at the screen because it happened so fast I couldn't take my eyes off the drone. It may have been after it was down that I looked and saw that. Hmm.

To me it would be good news.   One less possible Pilot Error.

DJI will want to see full FlightLog and BlackBox data from drone as part of any warranty coverage.

Nick1 Posted at 2018-7-1 22:09
[view_image]

Not pretty sight.  Sorry.  

HedgeTrimmer Posted at 2018-7-1 22:15
To me it would be good news.   One less possible Pilot Error.

DJI will want to see full FlightLog and BlackBox data from drone as part of any warranty coverage.

Yeah, that's what I'm hoping for. I have it all ready to send so lets see what happens.

Nick1 Posted at 2018-7-1 22:00
Is there any way to read these logs other than the one you showed me? I'm curious too. It was concrete and it usually never has a compass issue there, but it does happen and I bet it's got rebar in it. I do fly from this spot very often but not *exactly* the same spot. Previous flight before I had to calibrate compass, and that worked fine. This time, I'm almost positive it did not have a compass issue at takeoff, but there's still that possibility. It happened so quick, caught me off guard as I just took off and went to hover a ft off the ground and it just went it's own way. What would be the best way to approach DJI with this? Through the DJI care or support?

Based on Compass (magnetic field sensors XYZ axis) and sources of magnetic field interference I have done with Mavic Pro P; it can come down to a matter of inches as to whether or not steel rebar embedded in concrete causes little interference, lots of interference, or sufficent interference to cause compass calibration error messages.
Even rotating Mavic Pro P, over exact same spot would change amount of interference from Green (good to go) on main menu of GO-4 app; to Red (compass error).

Nick1 Posted at 2018-7-1 22:16
Yeah, that's what I'm hoping for. I have it all ready to send so lets see what happens.

Hopefully, there isn't anything that shows up in BlackBox data or drone's FlightLog file.  Issue being, more details in BlackBox data and finer granularity to FlightLog file.

Nick1 Posted at 2018-7-1 22:00
Is there any way to read these logs other than the one you showed me? I'm curious too. It was concrete and it usually never has a compass issue there, but it does happen and I bet it's got rebar in it. I do fly from this spot very often but not *exactly* the same spot. Previous flight before I had to calibrate compass, and that worked fine. This time, I'm almost positive it did not have a compass issue at takeoff, but there's still that possibility. It happened so quick, caught me off guard as I just took off and went to hover a ft off the ground and it just went it's own way. What would be the best way to approach DJI with this? Through the DJI care or support?

Is there any way to read these logs other than the one you showed me?

Yes if you have a Windows platform.  Forum member here (JJBspark) has very good program for looking at FlightLog data.  

I have not used program (I have Macs running OS-X); but others here have.   Update 2 Analysis program

Hi Nick,

Had a look at your flightlog to see what happendm mayby my charts will help you.
IMO the motor obstruction made your drone not steerable, see the pitch and roll angles.
DJI logic to write all data at the right sequence line is true but within some delay sometimes.

cheers
JJB

JJBspark Posted at 2018-7-1 22:40
Hi,

Had a look at your flightlog to see what happendm mayby my charts will help you.

Thanks JJBspark!  
I suggested your FRAP-2 program knowing it is very informative.  Phantom Helps flightlog viewer has a few minor glitches or missing pieces.

HedgeTrimmer Posted at 2018-7-1 22:44
Thanks JJBspark!  
I suggested your FRAP-2 program knowing it is very informative.  Phantom Helps flightlog viewer has a few minor glitches or missing pieces.

Thanks, now busy to implement KML data into FRAP-3  

And the last chart to show GPS signals and more...Compass error IMO due to crash angles and movement etc.

cheers
JJB

JJBspark Posted at 2018-7-1 22:49
Thanks, now busy to implement KML data into FRAP-3  

And the last chart to show GPS signals and more...Compass error IMO due to crash angles and movement etc.

Thank you so much for the analysis! Really appreciate it.
HedgeTrimmer thanks for your help as well. I've submitted and reported the log to DJI and I'll report back when I hear from them.

Nick1 Posted at 2018-7-1 23:17
Thank you so much for the analysis! Really appreciate it.
HedgeTrimmer thanks for your help as well. I've submitted and reported the log to DJI and I'll report back when I hear from them.

Hi Nick,

Its my pleasure to help other drone-flyers if i can.

I see that you are a novice flyer, mayby this checklist does help too.
(ofcourse there are many checklists, i do not pretend that this one is the best one)

cheers
JJB

Yes I am, I've only flown about 44 times and total 8 hours flight time. It's great fun, up until this point lol. I tried to use DJI Assistants log viewer, which is referenced by dji in many places but my latest version of assistant for PC does not have that option at all, glad to have been shown your program.

JJBspark Posted at 2018-7-1 22:40
Hi Nick,

Had a look at your flightlog to see what happendm mayby my charts will help you.

Looking at the flight log and location, controller taking drone up , everything looks ok, then controller starts to lower aircraft and we see motor error, he was flying very close to trees . IMO on the way down he clipped a tree, causing aircraft to fall, you can clearly see VPs altitude go quickly to minus figure.

hallmark007 Posted at 2018-7-2 01:57
Looking at the flight log and location, controller taking drone up , everything looks ok, then controller starts to lower aircraft and we see motor error, he was flying very close to trees . IMO on the way down he clipped a tree, causing aircraft to fall, you can clearly see VPs altitude go quickly to minus figure.

Hi hallmark,

Barometric height into minus values, VPS altitude from 3.9 to 0.1 at the end.

If the OP had hit a tree at short distance from where he stood, guess he would have said that.

After take off the OP pushed down, baro height into negative, takepoint highter than the surrounding area?


cheers
JJB

JJBspark Posted at 2018-7-2 02:11
Hi hallmark,

Barometric height into minus values, VPS altitude from 3.9 to 0.1 at the end.

there were no more stick movements after motor obstruction, and aircraft fell to the ground, I just wonder how you figure it was not steerable , if no stick movements were made ?
It looks from picture aircraft landed upside down.

hallmark007 Posted at 2018-7-2 03:36
there were no more stick movements after motor obstruction, and aircraft fell to the ground, I just wonder how you figure it was not steerable , if no stick movements were made ?
It looks from picture aircraft landed upside down.

If flying in GPS mode one or more engine are blocked (not by hitting something) and the pitch and roll angles goes from normal values to 50 - 80 degree values within 0.1 seconds ; IMO the AC becomes unsteerable, well for me for sure.

JJBspark Posted at 2018-7-2 03:47
If flying in GPS mode one or more engine are blocked (not by hitting something) and the pitch and roll angles goes from normal values to 50 - 80 degree values within 0.1 seconds ; IMO the AC becomes unsteerable, well for me for sure.

Yes it wouldn’t be steerable correctly but moving sticks on controller would show change in aircraft movement., But in many cases like this when Aircraft has motor obstruct it is because of hitting something and then falling, you will also see pitch and roll values change, the aircraft fell from 9. Ft to 0 with nothing recorded in between, if you check where aircraft was it was very close between trees and house and Pilot was trying to lower aircraft and it seemed to be reacting to all stick movements.

hallmark007 Posted at 2018-7-2 04:03
Yes it wouldn’t be steerable correctly but moving sticks on controller would show change in aircraft movement., But in many cases like this when Aircraft has motor obstruct it is because of hitting something and then falling, you will also see pitch and roll values change, the aircraft fell from 9. Ft to 0 with nothing recorded in between, if you check where aircraft was it was very close between trees and house and Pilot was trying to lower aircraft and it seemed to be reacting to all stick movements.

Agree, but as the OP did not say anything about hitting something...
If this drone flew into anything ; well no need to ask for what happend to this drone!If you look at his drone picture, no sign of 'green' on his blades.

Falling from 9 feet to 0 feet on VPS height in 0.1 sec , think VPS height gives wrong info, see pitch and roll angles ; not like a falling drone.
problem started earlier, see this data for extreme angles.

cheers
JJB

JJBspark Posted at 2018-7-2 04:56
Agree, but as the OP did not say anything about hitting something...
If this drone flew into anything ; well no need to ask for what happend to this drone!If you look at his drone picture, no sign of 'green' on his blades.

OP said he hit the side of the house, and VPs should be the correct height when aircraft is in VPs range, the sudden drop was caused by crash into house and crash looks like it caused motor obstruction. Aircraft was pushed first upwards and to the right by controller on throttle and rudder, these movements are correct as per log, then throttle100% down this is when it hit side of the house, motor obstruction and fell to the ground. IMO

I was thinking that the question was what happend, and more specific what happend before i hit the side of the house.....

About VPS height from 9.9 feet to 0.0 feet in (01:35:01.299 to 01:35:01.401) 0.102 second. that is 99 ft/sec = 67 mph.
A MA drone fly against a house, and increases its speed to 67 mph in 0.1 second from a Z-axis speed 1.5 ft/s and X-axis 0.9 ft/s speed with only minor damage?
Nah, VPS height values are not correct.



cheers
JJB

I think the values listed are inaccurate.

hallmark007 Posted at 2018-7-2 01:57
Looking at the flight log and location, controller taking drone up , everything looks ok, then controller starts to lower aircraft and we see motor error, he was flying very close to trees . IMO on the way down he clipped a tree, causing aircraft to fall, you can clearly see VPs altitude go quickly to minus figure.

I didn't hit a tree. When it first took off and I went to go hover, it started to go left and upward towards a tree which I then tried to get it back towards me to land, then it started going out of control that way, almost hit a parked car, I had to let it go upward a bit to miss that, then it started to fly right towards the house and up into the air, hit the side of the house and then fell to the ground. That's what happened. No trees were clipped.

In hindsight I wish it did clip the tree, it would've fell maybe 5ft into grass at that point and hit a much softer surface

The map trajectory is also wrong. It took off from the concrete seen in the picture to the left. I'll go take a pic so you can see what happened. They have also heavily been trimmed since that satellite imagery was taken. Crudely marked in blue is where I took off, it started going up and left towards tree, then right towards car and finally upwards and right into house. It would have had to gone much higher to initially clip that tree than it shows in the data. There's no other obstruction other than the house it could've clipped in the other direction.

Nick1 Posted at 2018-7-2 09:02
I didn't hit a tree. When it first took off and I went to go hover, it started to go left and upward towards a tree which I then tried to get it back towards me to land, then it started going out of control that way, almost hit a parked car, I had to let it go upward a bit to miss that, then it started to fly right towards the house and up into the air, hit the side of the house and then fell to the ground. That's what happened. No trees were clipped.

In hindsight I wish it did clip the tree, it would've fell maybe 5ft into grass at that point and hit a much softer surface

I understand that, but if you look in your log it shows you pushing on throttle and rudder so action of aircraft from this movement is up and to the right, very shortly it shows you pulling down on throttle 100% and it was during this movement aircraft hit the side of your house as you said, causing motor obstruction and falling to the ground.

This is how your log reads, whether there was drifting is difficult to tell in these logs, but all upward and downward movements are recorded in your log.

I realize this happens very quickly and panic can set in , looking at google maps it looks like you were in quite a tight space,
But your .dat file will show any strange movements outside of what we can see in phantom Help log, so you might have to wait for result from this file.

Being drone went out of control as OP said, what Flipping difference does it make if drone hit ten trees before hitting house and finally killing its Rogue fligjht?!?!
What matters is WHY drone went Rogue from start.

hallmark007 Posted at 2018-7-2 09:29
I understand that, but if you look in your log it shows you pushing on throttle and rudder so action of aircraft from this movement is up and to the right, very shortly it shows you pulling down on throttle 100% and it was during this movement aircraft hit the side of your house as you said, causing motor obstruction and falling to the ground.

This is how your log reads, whether there was drifting is difficult to tell in these logs, but all upward and downward movements are recorded in your log.

Yeah it started to drift as soon as it took off when I wanted a hover, so I tried to correct it slightly, but it kept drifting. At first it was a slow drift. There was no wind either, it was dead still outside. It did happen very quickly, I had some lawn chairs and obstacles so I couldn't just put it directly down. So I was trying to get it somewhere to put down safely as it was only semi listening to my inputs. Once it started to pick up speed and drift in the other direction to the left I realized it was really out of control.

It did happen very quickly. Here's a video which shows my usual flight path and the area, this was my second day with the drone still figuring things out

I've since gotten a little better. This was from a month ago