Massive crash when RSSI failsafe kicked in from drift mode

So I have been flying this hex for a few hours and have had great success. Was in a bigger area today with perfect calm conditions.

First flight of the day

Took off in Stab, then alt hold. Played in loiter then a bit to make sure things looked good.

Then switched to drift mode. Was flying around about 60’ off ground and then decided to stretch the distance a bit.

Went straight and level at not that great a speed. Got a low rssi from taranis. Then heard the failsafe alarm from Pixhawk. It went into RTL and immediatly started to flip and turn into the ground.

Log can be found here


What I’ve seen from your log that caught my attention is a massive brownout of the main batteries, that has coincided (perhaps) with the RSSI warning on the radio, right before the failsafe event. From there it is expected that there was not enough power to fly…

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Yeah, I saw that lastnight. I was pushing range a bit and was getting low rssi warnings so I didn’t think the brown out was the cause.

Just wasn’t sure if the brownout happened after the violent maneuver and that is what caused the brownout.

What log viewer are you using?

APM Planner 2.0 see 2.0.19-rc3 is the latest release

For those graphs above I was using APM Planner latest beta on a Mac.

Just added Vcc (power to PixHawk) where we can see a “severe” reduction of power to it at the same time, and the pop-up shows the relevant log lines.

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I’m just wondering if the violent breaking from Drift mode to RTL caused the power hit.

Here is the video from the crash. You can hear the Failsafe beeping right before the tumble.

Also here is the RSSI signal along with the VCC. Even though we see RTL point after power outage. how accurate is that point?

I don’t think that the mode change caused that, because you can see from the log that the mode change to RTL occurs after the problem with the power (most likely the RTL was triggered because of the power issue).

While I was testing the 3.3 I did lots of flights with a small quad and did lots of mode changes even on crazy situations and had no issues, and including testing the Emergency Stop function :slight_smile:

Do you have RSSI wired from the receiver to the PixHawk??.

If it was one my drones, and I know it’s almost impossible after a crash, I would look at main battery connectors, connections, before the Power module (if you’re using a standard configuration i.e. battery->Power Module->PDB) because the logs do indicate a problem on that area (momentary total loss of power).