Strange Spark Flight Behavior

Yesterday, I went to a Meet-Up “Fly-In” at Rowan University in New Jersey. I calibrated my compass before take off. The first two flights with my Spark were pretty routine - 11 minutes each with a minor downlink data loss of 2 seconds on the second one.

On the third flight the Spark travelled about 180 feet and lost connection at about 80 feet up. Restarting the Go4 App had no effect. When I restarted the remote I was able to reestablish connection and bring the AC down.

The 4th flight, which is included here, began with a routine RTH set, but after that, the AC took off on it’s own eventually landing 50 feet away after a multitude of error messages - I’ve never seen a Flight Log like this one.

http://phantomhelp.com/logviewer/7TC13NKM255Q2C4DN2T5/

After I recovered the AC and recalibrated the compass, I had another routine flight of six minutes.

I’m using IOS/Go4 on an iPad Mini4 - no OTG cable.

I’m wondering if I should send the Spark to DJI for evaluation - I have DJI Refresh, or if it may have been a result of disturbances in the local environment.

Can someone please interpret this log?

Thanks.

Please upload your DAT flight log. If needed, you can find instructions for retrieving it here. If the file is too large to attach here, upload it to a file sharing site (like Dropbox) and post the download link here.

Mike,

Thanks for the response. I’ve never been able to access .DAT files on my Spark with DJI Assistant on my MAC. I never see a file listing, just a spinning wheel. . . .

I did find a .DAT file on my mini4 iPad that I’ve attached.2018-08-12_10-08-20_FLY197.DAT (682.9 KB)
2018-08-12_10-08-20_FLY197.DAT

Thanks,

The cause of this incident is launching from a geomagnetically distorted site. I’m guessing the launch site was directly over some rebar in that parking lot. Were there parked cars close to the launch site?

At launch the actual heading was about 150° but the Spark’s FC thought the heading was -160°. You can see this if you replay the flight using the Go App.

You can also check this before flight by looking at the red triangle heading indicator in the Go App map display and determine if it’s consistent with the AC’s actual orientation. Here’s what it would have looked like.

image
The red A is the location. The green line is the FC’s heading value and corresponds to the red triangle heading indicator in the Go App map display. The orange arrow is the actual heading.

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Interesting and informative response! looks like I have one more thing to add to my Take Off Check List. The attached pic show how desolate the parking lot was on Sunday morning. There were several other pilots but I was the only one who experienced this behavior. I had 5 other launches without issue.

I guess it all comes down to paying close attention to what your readouts are telling you.

Thanks for the quick analysis!

It would also help if you stop calibrating the compass before you take off. That can cause some issues. The compass calibration only needs to be done when the app tells you too. Usually the very first time you fly after buying it. Compass calibrating is not necessary or required before every flight.

I only calibrate when the Go4 App indicates it is needed. This usually happens when I’m flying at a new location as was the case on Sunday. Thanks for the imput!

Which message did you see in DJI GO that made you think the compass needed to be calibrated?

That is very unusual. It should not indicate that a calibration is needed just because you are at a new location. I have been a thousand miles from home and not needed a calibration.
I think you are mistaking the calibration option that comes up when you first start the GO4 app as a warning.
Did it say “Compass calibration needed” in red across the top of the app?

The “Calibrate Compss” in the AC Settings menu was highlighted.

I did not see any notice on the main screen.

If you’re referring to the button in the screenshot below, that’s just a quick shortcut to start the compass calibration (if you want to do it for some reason).


 

While calibrating the compass before a flight won’t hurt anything, it’s usually not required. If you’re not sure when you should be calibrating the compass, then check out the Spark Compass Calibration Guide for the best known practices.

Hmmmm, that sounds logical. I would have thought there should have been some flag about the conflict between the displayed vs actual bearing for the “problem” flight, but that may be too much to expect from an entry-level drone. This has been an education for me. Thanks!

PS: and this was always available on the spark tips!

The “displayed” heading is what the Flight Controller thinks is the heading. The FC can’t know if this value is consistent with the actual heading since it only has magnetometer data to determine heading. This will be true of any drone. Only the pilot can determine if there is a discrepancy between the FC’s heading and the actual heading.

It’s really unfortunate that DJI doesn’t mention this in any documentation or user manual. This simple check would have prevented many fly aways.

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