Hovering in Loiter - Rolled into the Ground


Mission Planner: 1.3.24
Pixhawk Firmware: 3.2.1

The quadcopter was hovering at about 20’ AGL when it rolled straight into the ground. I noticed there was a GPS glitch right before the crash. Is that the issue?
The GPS glitch param is set to ALt Hold.

Here is the log:

dropbox.com/s/6novg7vsppuin … 2.bin?dl=0

Upon repair I updated to Mission Planner 1.3. 25. I’m concerned with the compass offsets2. They are as follows:

I’m a bit paranoid now. Are these offsets of concern?



I would put your files either in the Google Drive or zip them as dropbox wants you to become a member to download your files.


Here is an Auto Analysis of your bin file:

Size (kb) 5893.009765625
No of lines 79764
Duration 5 days, 17:30:40
Vehicletype ArduCopter
Firmware Version V3.2.1
Firmware Hash 36b405fb
Hardware Type
Free Mem 0
Skipped Lines 1

Test: Autotune = UNKNOWN - No ATUN log data
Test: Balance/Twist = GOOD -
Test: Brownout = GOOD -
Test: Compass = WARN - Moderate change in mag_field (33.28%)
Max mag field length (664.60) > recommended (550.00)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: CRASH
Test: GPS = FAIL - Min satellites: 0, Max HDop: 99.99
Test: IMU Mismatch = WARN - Check vibration or accelerometer calibration. (Mismatch: 1.14, WARN: 0.75, FAIL: 1.50)
Test: Parameters = GOOD -
Test: PM = FAIL - 28 slow loop lines found, max 14.93% on line 52183
Test: Pitch/Roll = GOOD -
Test: Thrust = GOOD -
Test: VCC = GOOD -

Looks like you may have an IMU issue and you did indeed have a GPS glitch.


Thanks TCIII,

I ran the auto analysis and got the same results…which should be expected, I suppose.

Do you think one event caused another (i.e. the GPS Glitch occurred then triggered the IMU issue)?

The aircraft is back together, but those compass offsets are the big concern now.

The RTL before the loiter before the RTL crash your front right motor was maxxed out, I’d say either a motor or esc failure.

The gps error shown by the auto analysis is a red herring which comes up a lot in my logs. When you actually look at the logs you can see your gps hdop is 99.99 and sat is 0 but that’s because you have just powered everything up. By the time you arm and take off you have 10sats and an hdop of 1.93 which you maintain through out the flight.

Thanks MarkM.

I’ll take a look at the log and see if I can figure out how to determine what you came up with regarding the motor/esc issue.

I noticed the following:
At 12:29:58.600 the satellite count was 10 with HDOP at 1.93.
At 12:29:58.800 the satellite count drops to 9 with an HDOP of 2.29.

Is that GPS glitch a concern?
Thanks again!

I give up MarkM. What do you graph to determine a motor is maxxed out?

That shift in GPS looks like it’s after you start having motor problems.

If you scroll to the bottom of the list (bottom right of log analyser) you will find RCOU, chan1 to chan4 correspond to motors 1 to 4.

I’ve been researching/surfing for hours to find these answers. Hopefully, I’m getting smarter.

Thanks so much to MarkM!