Spooky, first time i've almost lost it, what happened?

[CRCs Reality]

Wow.. So, took my .dat file and ran it through BudWalkers great DatCon tool, then used the instructions and profile from his website (created by @Luap ) for dashware and created this video of the flight:

I'm amazed at the number of YAW_ERROR_LARGE and COMPASS_ERROR_LARGE errors being thrown at a time Litchi gave no indication of any problems at all.. A bit unsettling at least as I've flown with Litchi almost exclusively, and never had any problems prior to this.

Again, appreciate all the help in this thread folks, I'm glad to have an understanding of what happened and why.

 

[BudWalker]

Wow.. So, took my .dat file and ran it through BudWalkers great DatCon tool, then used his instructions for dashware and created this video of the flight:

I'm amazed at the number of YAW_ERROR_LARGE and COMPASS_ERROR_LARGE errors being thrown at a time Litchi gave no indication of any problems at all.. A bit unsettling at least as I've flown with Litchi almost exclusively, and never had any problems prior to this.

Again, appreciate all the help in this thread folks, I'm glad to have an understanding of what happened and why.

I'd really like to have a copy of that .DAT please. It looks very much to me like you launched from a spot that was geomagnetically distorted. We can determine more with the .DAT.

The Dashware stuff is all due to @Luap. He did the instructions, videos, and the profile that you used.

 

[Multicoptertec]

That courthouse roof is probably chock full off comm antennas, emitting who knows what on a Pandora's box of frequencies.

 

[CRCs Reality]

I'd really like to have a copy of that .DAT please. It looks very much to me like you launched from a spot that was geomagnetically distorted. We can determine more with the .DAT.

The Dashware stuff is all due to @Luap. He did the instructions, videos, and the profile that you used.

Dropbox link to my .dat files

 

[CRCs Reality]

First time I've messed with Dashware, really slick for certain situations (like this one)..

Interesting how the MagMod tanks right at takeoff, wish I understood more of what that means.

 

[BudWalker]

First time I've messed with Dashware, really slick for certain situations (like this one)..

Interesting how the MagMod tanks right at takeoff, wish I understood more of what that means.

Nice video! You've really done a lot with Dashware in a very short time. It's always been a struggle for me.

magMod can be thought of as a composite view of the 3 magnetometers. Specifically, magMod=sqrt(magX^2+magY^2+magZ^2). magMod is the same value you see when you look at the DJI Go App Sensors page.

I'm looking at your incident. At first glance it appears to be like several other incidents described in post #11. This one is a little different. The change in magMod isn't as abrupt and there are additional COMPASS_ERROR_LARGE errors after the initial COMPASS_ERROR_LARGE error goes away. I'm still looking at this.

You had lots of COMPASS_ERROR_LARGE errors

The light blue background is COMPASS_ERROR_LARGE and the pink/beige is YAW_ERROR_LARGE

 

[Anthony Radford]

Lately, I've noticed my P3P frequently self-switches from GPS to ATTI mode and back. Even when flying in a field fairly close to where I'm standing- less than 500ft away and under 100ft AGL, and no (visible/known) metal interference around. Not even concrete... (Using an asphalt parking lot for ground operations)

I use the DJI GO app, as I can't bring myself to purchase Litchi, being it does basically what GO does. All devices and apps are at current update, AC is in perfect condition- no crash damage, etc.

Any ideas why a bird will repeatedly switch between modes? All antenna and satellite info looks strong as well.

 

[shockwave199]

First time I've messed with Dashware, really slick for certain situations (like this one)..

Interesting how the MagMod tanks right at takeoff, wish I understood more of what that means.

It's one thing to read that you took off from a parking garage but it's another thing to see it. You were very lucky, that's for sure. Don't ever do that again. Take off from an asphalt parking lot, no problem there. Just not ever from concrete sidewalks or the granddaddy of them all, a parking garage.

 

[CRCs Reality]

It's one thing to read that you took off from a parking garage but it's another thing to see it. You were very lucky, that's for sure. Don't ever do that again. Take off from an asphalt parking lot, no problem there. Just not ever from concrete sidewalks or the granddaddy of them all, a parking garage.

Yeah, in hindsight it was a bad plan.. I figured if I got up 5 feet or so with no compass errors (at least none Litchi showed me) that I was OK.. I was very wrong apparently.

I suspect this is how some flyaways may have started, I mean, I've flown RC planes and helicopters for years prior to getting this P3P so coming back in ATTI wasn't bad. And even with that, I almost panicked and just hit RTH, which likely would have sent it flying away from me.

Funny, watching the video it was a very short flight, it felt like 20 minutes or more when I was trying to bring it back once I realized I had a problem

 

[flyNfrank]

Lately, I've noticed my P3P frequently self-switches from GPS to ATTI mode and back. Even when flying in a field fairly close to where I'm standing- less than 500ft away and under 100ft AGL, and no (visible/known) metal interference around. Not even concrete... (Using an asphalt parking lot for ground operations)

I use the DJI GO app, as I can't bring myself to purchase Litchi, being it does basically what GO does. All devices and apps are at current update, AC is in perfect condition- no crash damage, etc.

Any ideas why a bird will repeatedly switch between modes? All antenna and satellite info looks strong as well.

Need to at least see your txt flight log file. But a common reason is due to the lack of satellite signals being received. When you see this error take place, you might try to climb up to a higher altitude, hover, and make say 3-4 360 degree rotations. and take note if there is any improvement. If there is Not, then be prepared to manually switch the A-mode on the R/C and fly back to your home point. If you are struggling because of strong wind and do not feel good about the attempt to get back, then Land the Aircraft and go retrieve it! Keep in mind when you receive a Compass Error the longer you stay in P-mode in that situation, the better chance the crash may fly off or crash on it's own.

Any time a Compass Error happens, DO NOT select RTH.

 

[Flintstone]

So, after almost 80 flights with zero issues at all I had a scary one today.

Got to the courthouse early, and figured I'd launch from the roof of the parking garage (yeah, I know) and get a nice shot of town above the courthouse.
I was very careful to check for any compass errors (again, parking garage), but all looked good so I went up to just below 400' and started to move into position for a panorama shot.

At that point, the status went from "P-GPS" to "ATTI" and yellow, and the P3 started drifting with the slight breeze. I lost most control, but not quite all.
Thankfully, I had seen many posts where people panicked and hit RTH in this situation, causing a flyaway (can't RTH with no GPS, right?) so I switched to ATTI mode and was able to slowly bring it back over me and down for a landing.

Here's the problem(s):
1 - when coming back in ATTI mode, the controls were VERY sluggish, I had to peg the controls to get much movement at all, and wind wasn't a factor. It was really weird, I've flown in ATTI before to get used to it, and something was definitely wrong.

2 - Looking at the HealthyDrones logs, I expected to see GPS problems, but there were only a few (10-15 instead of 15+) and only close to where I landed.. Through most of the loop where I was forced into ATTI and had very little control, I had solid GPS and Compass readings. ( Healthy Drones Logs of the flight)

It's shaken my confidence a little, I do have the .dat file from the drone, but really don't know what to do with it to try and unravel this mystery..

Any input from those with more flight time than me as to WTF happened?

First you have guts flying from the parking garage of the courthouse! Thanks for not falling out of the sky and hitting someone, drone pilots have enough idiots making them look bad. I will say possibly the courthouse had some communication antennas on it most I have seen do. Could be RF interference. If your parking garage has concrete with rebar in it that is a bad place to set compass and home point. I don't like to stir the pot but flying in the city is asking for trouble that ripples through the entire drone community. Fly safe not stupid please.

 

[CRCs Reality]

I don't like to stir the pot but flying in the city is asking for trouble that ripples through the entire drone community. Fly safe not stupid please.

WOW..

Just to be clear, I parked one block away, with the intent of flying one block over (where the P3P was only above buildings, I picked the launch spot specifically because it didn't involve passing over anything busier than an alley) and shooting a panorama from above a building.
And with that, after launch I hovered for a moment and watched for any errors that would have indicated any issues. Once the P3P got to altitude, it became apparent that there was a problem, so I put it in ATTI and brought it quickly back down. Aside from some clenched cheeks, there were no issues, and even if it HAD dropped from the sky at ANY point of the flight, the drone would have been the only casualty.

Oh, and then I came here to ask for input (which I got, thank you) on what caused the issue so I could avoid it in the future.

You know, I'm quite careful when I fly, and take steps to NOT be "That guy".. We were at an event tonight that would have made an awesome drone video, and I left it in the car because there were crowds.. Be careful who and how you judge..

 

[Vertigo]

WOW..
even if it HAD dropped from the sky at ANY point of the flight, the drone would have been the only casualty.

Ive definitely seen worse, Im not going to scold you, but what do you think could happen if the drone fell on the windshield of a driving car? On a the head of a small child? What if a police, press, or hospital helicopter came speeding from a downwind direction that you didnt hear coming? I know, it sounds like a one in a million chance, and it probably is. The problem is that are millions of these toys flying these days, so I much prefer to see them flying in unpopulated area's.

BTW, and just FYI there could also be legal issues. AMA guidelines state this: "

• Do not fly near or over sensitive infrastructure or property such as power stations, water treatment facilities, correctional facilities, heavily traveled roadways, government facilities, etc."

Im pretty sure the courthouse would fall under that. You might think because its a guideline, its not that critical, but you would be wrong, as complying with AMA guidelines is the only thing that exempts you from FAA general aviation rules. If you dont comply, FAA can treat you as if you where flying a cessna or 747 there.

 

[pomonabill220]

Just to add to this discussion, and NOT try to preach, two things struck me.
1) When you launched it looked like you might have been pretty close to your car? That could have added to the compass problem?
2) I did notice the antennas on the structure several feet away, and questioned the affect of RF, BUT when you came back down the flight mode didn't switch around like it did when you took off, so the question about RF interference comes to mind. Also, IF RF interference could have been a problem, what kind of problems would/could a helicopter have? After all, the helipad was close to where you were, and although they have several different compasses (radio/gyro/mag), it still could affect at least one of them IF RF was a problem.

Just some questions that I had about this situation...

 

[CRCs Reality]

Just to add to this discussion, and NOT try to preach, two things struck me.
1) When you launched it looked like you might have been pretty close to your car? That could have added to the compass problem?
2) I did notice the antennas on the structure several feet away, and questioned the affect of RF, BUT when you came back down the flight mode didn't switch around like it did when you took off, so the question about RF interference comes to mind. Also, IF RF interference could have been a problem, what kind of problems would/could a helicopter have? After all, the helipad was close to where you were, and although they have several different compasses (radio/gyro/mag), it still could affect at least one of them IF RF was a problem.

Just some questions that I had about this situation...

1 - Maybe, but I've launched that close to the back of the car previously with no ill effects, the P3P was probably 15 feet or so from the back of the vehicle.

2 - Helipad?

 

[skipilot1]

I missed this info about litchi. When I had my compass error I too was using litchi and received no warning. My error happened much lower at around 75'. My only indication there was a problem was the sound of the bird flying away to my left. I was in the process of opening up a waypoint mission during what I thought was a hover. There was no warning in litchi. Upon landing, like you in atti mode behavior (not having switched to atti mode myself) I opened the dji app to see compass error in red. What I am most spooked about is the failure of litchi to ever warn me of the problem. I mentioned it in the Google group and support wasn't really too specific about an answer. I think they believe errors should be reported in the app but I'm not sold they know for sure they will all be. Like you, HD showed nothing of the incident. So, I use Litchi with caution. I absolutely do not use only the litchi app for any flight because of this. I've lost confidence in its error reporting. Each flight I start in the dji app, get airborne in that app, and confirm stability in that app. Then I swipe closed and go into litchi to continue. If I'm just flying around, I've only flown litchi a couple times to check out fpv (ios version catch up) but I much prefer the dji app, actually. I like Litchi a ton for waypoints and orbit, etc. But when the chips are really down for critical must-film situations where I must fly manually, I find much prefer the dji app. I knew that would be the case all along for me. I use Litchi and like it but I believe that overall the dji app is best for overall flying. But when you're certain the bird is stable and all is well, litchi is awesome too for what it offers.

Before using Litchi, I always start up in DJI GO and check all settings and sensor readings and bring it up to at least 30 meters. I check for stability by hovering and moving the bird around. Only when I believe it is acting normally do I exit the app and start Litchi. I don't know what happened on the parking deck, but I would suspect that if the DJI app was used and all readings checked, then some type of error must have come up given all the potential interference. If there was no error, but the sensor readings were outside the normal range (assuming the pilot keeps track of what that range is) then that would be enough reason to cancel the flight.

Recently I was on a deck at a lake. Before taking off, I checked the sensor readings and the compass, that while not showing an error, had a higher reading than normal. I picked up the drone for a hand launch and the readings went back to its normal range.

 

[pomonabill220]

1- hhmmm.... well it was just something that caught my attention.
2- on the far corner of the building next to the parking structure you can see what appears to be a helipad as you ascend.
It doesn't have the "H" marking that helipads normally have on it, so don't know if that is what it is.

 

[pomonabill220]

Still would be interesting to find out what caused the fast mode switching... a mystery!

 

[CRCs Reality]

1- hhmmm.... well it was just something that caught my attention.
2- on the far corner of the building next to the parking structure you can see what appears to be a helipad as you ascend.
It doesn't have the "H" marking that helipads normally have on it, so don't know if that is what it is.

Nah, no Heliport anywhere nearby , and I also checked with UAV forecast prior to launch in case I was missing one (not that it couldn't be wrong, but it's usually pretty good).

I suspect the reason is as BudWalker was suggesting, heavy interference from the metal structure in the parking garage threw the compass off during initialization of the bird. Then once it cleared the interference and started producing accurate compass readings, they didn't jibe with where the GPS thought it should be so it started failing over into ATTI.

Still bothers me that Litchi didn't indicate any errors onscreen until it was a few hundred feet up.

 

[BudWalker]

Nah, no Heliport anywhere nearby , and I also checked with UAV forecast prior to launch in case I was missing one (not that it couldn't be wrong, but it's usually pretty good).

I suspect the reason is as BudWalker was suggesting, heavy interference from the metal structure in the parking garage threw the compass off during initialization of the bird. Then once it cleared the interference and started producing accurate compass readings, they didn't jibe with where the GPS thought it should be so it started failing over into ATTI.

Still bothers me that Litchi didn't indicate any errors onscreen until it was a few hundred feet up.

Actually what I said is that Flight Controller's Yaw value was different from a heading value derived from the magnetometers. This is what caused the COMPASS_ERROR_LARGE errors. GPS wasn't involved.