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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Perhaps vibrations affect a connection?

went back to 3.2 seems fine. I highly suspect it's APM2... guess I'll post over there and see if Bill has any idea's.

I had the same problem with APM2.  Just reload with the latest beta APM Planner and it should work fine.  It is an APM planner issue that has been addressed.


Richard, you installed AC 3.3 rc5 on APM 2?

I was thinking that the highest compatible version of AC for APM 2.x is AC 3.2.1

We are referring to APM Planner 2.  Mac OS GCS

Checked it just now. I remembered that incident as soon as I started reading it.

So it is still flying!..:)

I got you now but it really doesn't seem like it in the text... 

Excellent thank you I will try that. 

Yes your right that corrected that. Great!! Thanks...

But..... my teensy lua script no longer works. Bummer.... very handy. No GCS needed. Not sure where to look to address that problem. I did set the  SERIAL2_PROTOCOL to "3" as suggested. The X8R receiver is getting telemetry just no data from the pixhawk it seems. 

Now if I get DCM bad heading I won't know... sweet!! Fixed!! LOL 

Should have said APM P2 sorry my mistake. 

Hi UAS_Pilot,

I can confirm looking at the logs that the autopilot wasn't running when you crashed. It looks like you lost power to the pixhawk.

Sorry about your crash!!

Hi Gregmaan,

I would encourage you to set these parameters


These are the parameters that linearise the lift of your props and ensure your tune stays right as your battery goes flat and as you increase and decrease your throttle.

I will need more logs of your autotune on roll and pitch before I can help you further. I can tell you that you don't expect your roll and pitch pids to be the same on a hex though.

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