Warning #1: an issue has been found with Tower's Pause button which can cause the vehicle to fly to an old position if the vehicle has not sent a position update to Tower in some time.

Warning #2: Copter-3.3.2 fixes a bug found in Copter-3.3.1's desired climb rate initialisation which could lead to a sudden momentary drop when switching from Stabilize or Acro to AltHold, Loiter or PosHold.

Warning #3: Copter-3.3.2 fixes an issue found in Copter-3.3.1 which could lead to hard landings in RTL or AUTO if the WPNAV_SPEED_DN was set too high (i.e. >400 or 4m/s) and/or the WPNAV_ACCEL_Z was set too low (i.e. <100 or 1m/s/s).

Warning #4: a bug was found in Copter-3.3 which could cause a sudden crash if you abort a Take-off initiated from a ground station.  Video description is here.  The bug is fixed in Copter-3.3.1 so we recommend upgrading.

Note #1: AC3.3-rc8 corrected a long standing bug in the HDOP reporting.  HDOP values will appear about 40% lower than previously but this does not actually mean the GPS position is better than before.
Note #2: if upgrading from AC3.2.1 the vehicle's accelerometer calibration needs to be done again.
Note #3: set SERIAL2_PROTOCOL to "3" and reboot the board to enable FrSky telemetry like in previous versions.
Note #4: the wiki will be updated over the next few weeks to explain how to use the new features

Copter-3.3.1 is available through the mission planner.  The full list of changes vs AC3.2.1 can be see in the ReleaseNotes and below are the most recent changes since AC3.3.

Sadly this version (and all future versions) will not run on the APM2.x boards due to CPU speed, flash and RAM restrictions.

Changes from 3.3:

1) Bug fix to prevent potential crash if Follow-Me is used after an aborted takeoff

2) compiler upgraded to 4.9.3 (runs slightly faster than 4.7.2 which was used previously)

Changes from 3.3-rc11:

1) EKF recovers from pre-arm "Compass variance" failure if compasses are consistent

Changes from 3.3-rc10:

1) PreArm "Need 3D Fix" message replaced with detailed reason from EKF

Changes from 3.3-rc9
1) EKF improvements:
    a) simpler optical flow takeoff check
2) Bug Fixes/Minor enhancements:
    a) fix INS3_USE parameter eeprom location
    b) fix SToRM32 serial protocol driver to work with recent versions
    c) increase motor pwm->thrust conversion (aka MOT_THST_EXPO) to 0.65 (was 0.50)
    d) Firmware version sent to GCS in AUTOPILOT_VERSION message
3) Safety:
    a) pre-arm check of compass variance if arming in Loiter, PosHold, Guided
    b) always check GPS before arming in Loiter (previously could be disabled if ARMING_CHECK=0)
    c) sanity check locations received from GCS for follow-me, do-set-home, do-set-ROI
    d) fix optical flow failsafe (was not always triggering LAND when optical flow failed)
    e) failsafe RTL vs LAND decision based on hardcoded 5m from home check (previously used WPNAV_RADIUS parameter)

Thanks for your testing!

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Hello Richard,

all my props are fine (just one slight cut-in at one prop which definitely came from the crash) even after the 60m drop. I was really lucky.

I use Aeronaut CamCarbon light 13x6 props.

Here is a pic I made after the crash.

Yea I’d say your quad looks damn good for a 60M crash! This is probably unrelated but one thing I had happen once was somehow two of my arms got twisted and as luck had it it was two opposing arms hence the motors spin the same direction. What happened then was it could not compensate for the yaw effect that caused so even with full right yaw stick it continued to yaw left. However it didn’t cause a crash and of course it was evident the moment I took off. In my case the aluminum arms get bent slightly in travel. I was amazed at how little it took to create that much of an issue. Just looking at yours I wonder if two of the motor mounts twisted on those round arms? But of course the log would show it trying to compensate with full yaw opposite it's actual yawing. 


Your copter looks like it rotates more than 25 times during that crash. The log you show takes 45 seconds from full throttle to the time it gets to the ground and doesn't spin. Your video takes 13 seconds to crash and spins 25 ish times.


I can see you don't know how to read logs and are here because you need help understanding what happened. The dev that designed the controllers in arducopter is telling you that the log you provided is not the same log in your video.

Please take the time to listen to the people that are trying to help you. You are currently wasting the time of the helpful people on this forum that are trying to help you.


yes, you convinced me already. Just didn't have the other logs here (just the one I uploaded) and didn't have time to look after it just yet.

I was so sure that this was the right log, that I just wanted to show you, why I felt so sure. (errors and map).

You are of course way more experienced and into the whole topic so that it was clear to you from the first second that it isn't the right log.

I will look for the right log as soon as possible!

Sorry for the inconvenience caused.

Thanks for taking your time.

Richard Kennedy:

Yeah, I was really really lucky. It was the perfect place to crash (freshly loosened slightly wet field). I still wonder how the landing legs could survive :D

The motor mounts are twisted because of the crash. They were solid and straight before. (They are just clamped with a screw, there is no bolt going through the carbon fiber)

Hi Dave,

Thanks for that, no problems! 

Did a quick test flight today with my Hexa Copter version 3.3.1. Rebuild to reduce vibrations. Did all calibrations, but now i get compass variations during flight.
Can someone please advice ?



You were right, here is the correct log, which shows information that matches the behavior seen in the video.

I am really sorry. That should not have happened. The timestamp of the video was wrong so I focused hard onto the wrong log..

Thanks for looking into it again. Hopefully we can find the cause now.


re- log confusion... I have that confusion myself MANY times. Sometimes they are listed in a different order on the SD card than on my HD which makes it easy to make a mistake. 

I setup a sync issue test bench.

I measured the exact signals with my scope and built a small tool to output the exact values the flightcontroller does with an fpga module.

here is a video. in the top chart, you can see the pwm value, in the bottom chart, you can see the current.

Looks all fine until now :(

I uploaded the right log as an answer to the first post now, thanks for having a look :)

What transmitter is that? Are the voice/speakers stock?

HobbyKing's 'Taranis-killer' (ok, exaggerated, but it's HK) is on sale for 50% off right now - the Turnigy 9xr Pro.

$50 instead of $100, for Black Friday.

Includes speaker and voice alerts. Some people are hacking the speaker for more volume, and substituting their own audio files (see dedicated thread on RCGroups.com).

I've ordered one. It's HobbyKing, so wish me luck.

(hope I'm not violating TOS by mentioning this)



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