I have just lost control of my X8 last Friday during a survey mission using the APM2.5 and Mission Planner 1.2.4x and ArdoPlane 2.72.

Having a successful flight the previous day, I could not get the autopilot to fly to my first waypoint although in Auto mode. I had to rain the plane back in intervening manually and using RTL which was also unusually slow to respond. After landing I uploaded a new flight plan which caused even greater havoc after take-off letting the plane fly too low during RTH and not accepting the AutoMode at all. I lost radio contact with the plane which flew behind a dump and the throttle speed was not activated correctly in Fail Safe mode so that the plane crashed. Attached are the logs of the two flights. The APM only logged the first flight but the log of the second was corrupted. Both logs below are from the ground station.

Can anyone give me some useful advice on how to prevent such a situation in future?

With kind regards


2013-05-11 11-36-58.tlog

2013-05-11 12-07-15.tlog

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  • Hi,

    You seriously had 121 waypoints loaded? And do you live in South Africa?

    Yes the navigation appears totally busted. Hunting around in a never ending left turn for a WP that is 500 meters away (if circling around it caused the hunting, there was a rational explanation....)

    The compass seems to be okay.

    There was several bugs discovered in 2.7.2. All I can advise you is try upgrade to 2.7.3 and see if the problem is still there.



  • Hi,

    I will try see if I can find out something (I am not an official APM dev.).

    What I can think of from the top of my head -

    - Did you make sure the GPS altitude was correct before takeoff? It happens (too often I think) that a very early GPS position with a very bad altitude is accepted and that is used for home altitude. The altimeter will be off for the whole flight. Since many people use "relative to home altitude" in their missions, the same error applies to the waypoints and they will be all right after all. Did you have relative or absolute altitude on your WPs?

    - Version  2.7.2  would get confused about two successive navigation wapoints at the same place

    - Do you have also the mission file and the onboard log?

    - Your parameters? Especially if you had "use airspeed" on, and the ALT_HOLD_RTL parameter.



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