occasional failure to takeoff

[zimmy87]

When running the PX4 JSBSim bridge via make px4_sitl jsbsim on Ubuntu 18.04 and with QGroundControl connected, I'm finding that about every other attempt to takeoff after uploading a mission will fail with the drone falling out of the sky. When this happens the PX4 console outputs a poll timeout 0, 22 error and QGroundControl outputs a Critical failure detected: lockdown dialog.

[Jaeyoung-Lim]

@zimmy87 Could you share the whole log of the output?

I am wondering if there is somekind of race condition on startup.