Dropping Quad (THROW MODE) from altitude, unexpected climb after recovery?

Hello! In line with my previous post, we’re continuing to experiment with THROW/DROP mode on a small 5" quadcopter running a custom version of Arducopter (where the velocity requirement to trigger a drop recovery has been increased to 9.9m/s). We drop this small quadrotor (while it is armed in drop mode) from a larger quadrotor, and the smaller copter will automatically fall, recover and follow a mission. We’ve had a lot of success so far!

A strange issue we’ve been seeing very occasionally is that the copter will climb aggressively after recovering, which is exactly what we DON’T want to happen as we want to avoid midair collisions. After reviewing the logs, the only thing we can see is that GPS altitude and barometric pressure don’t seem to align in time, and we’re wondering if the EKF filtering is getting messed up as a result…however we could be way off base.

If anyone has the time, would you guys be able to check out this log (of exactly this event) and maybe explain why this is happening? I’d love to tweak a few parameters to prevent future instances.

Thank you!

LOG: Drop Log 2-10-2025 - Google Drive

Need to get a replay log of this occurring if its EKF related

Ah okay, thanks for the tip, I can make sure that’s enabled for future testing. We’re not sure it has to do with the EKF, it was just a thought that it might be the culprit. I figured there was a chance somebody more versed in log analysis may see something we missed.