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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Yes, extremely, extremely high vibrations on that one.

Anyone able to advise on this?

Nice video!!!

Amazing. Those motors sound lower than 300kv.

I could be wrong, but isn't the GPS settings overwritten by the AC code when booting? So it seems the code itself must be edited to accept the desired changes.

They are unless you remove the RX pin from the GPS lead

A while back there was chatter about the X series of receivers from FrSky transmitting out of band and affecting some GPS units. Do you happen to have one such as the X8R? If so maybe moving the RX as far away from both the GPS and GPS leads as possible and see if that doesn't help mitigate the issue.

Before Mission Planner was displaying PDOP but instead of just changing mission planner to "say" PDOP they change ArduPilot to instead read/display HDOP and I'm not 100% certain they have it right yet.

Well it does have over 400 log files :)  Guess that makes me a log hoarder.

But the AUAV-X2 has over 200 and works fine.

Seems like the Pixhawk has always had trouble pulling logs via MP though. I may format the SD card and reload, but will first clear out the log files.


     I was in the process of reviewing some VIBE_X/Y/Z data from some recent flights when i noticed mission planner reporting that I was using flight modes that were not selected during the flight. This problem has only occurred using RC-8.

My Tx is setup to only use Acro / Stabilize / Alt Hold flights modes using a 3 POS switch. When reviewing the flight in mission planner it claims that i've used Guided / Circle / and Manual modes repeatedly in flight while none of them were selected nor reported from MP's spoken voice...


Link to .bin file


Link to .bin file

Secondly when lowering the ATC_ACCEL_P_MAX and R_MAX values what is presumably the lowest these values can safely go? I have manually tuned my multi to ~0.35 Rate P for roll and pitch while lowering the ATC_ACCEL values (Currently ATC_ACCELL_P/R are 20000 down from autotune set value of 96000). The overal flight experience is fairly smooth but i'm worried as of to the minimum value of those parameters and what may happen if they go to low? Is this an indication of a severely overpowered multi?

Also, Has anybody figured out what good values we should expect to see while using the new Vibe tab in 3.3? my Acc values are fairly low (using the vibration drop down menu) however the VIBE graph from RC3.3 looks far worse in that bin file. Are there certain frequencies / conditions that are not picked up on 1 that the other tab can see? Comparing the above graph from this one highlights my concerns


The flight mode thing is certainly a mission planner issue.  Most likely it's confused as to whether the log is an Plane log or a Copter log.  When I open the log I only see Acro, Stabilize, and AltHold flight modes.

Those vibration levels are great!   It's mentioned on the Measuring Vibration wiki page but in short, below 15m/s/s is good, Above 50m/s/s is bad.  Clipping is bad.  Your vehicle is averaging about 4 or 5m/s/s and no clipping so very good.

I think the dropped messages are more likely:

1. a serial bandwidth when the number of satellites is very high

2. GPS internal speed limitation that means it can't keep up with all that it has to.

3. a logging problem - we log a lot of data in AC3.3 so the SD card may not be able to keep up.

There's an issue on the issues list here about the M8 and configuring it to reduce glitches.

Reducing the update rate of the GPS to 2hz is not a good idea.  The EKF wants it at 5hz.

The thing about the Vibe message is that you aren't looking at the "spiky-ness" of lines, but merely the maximum height. In your case, about 8 max on the green line, is quite good.

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