JSBSim hexarotor_x SITL spawns in air above Zurich airport and fails to arm (Ubuntu 24.04)

[Achyuth_G_S]

Hi PX4 community,

I’m trying to run PX4 SITL with JSBSim using the hexarotor_x model on Ubuntu 24.04, but I’m facing an issue where the vehicle spawns already high in the air above Zurich airport and I am unable to arm or control it.

Setup

• OS: Ubuntu 24.04

• PX4 version: v1.16.0

• Simulation: JSBSim Version: 1.1.13

• Model: hexarotor_x

• Launch command:

  make px4_sitl jsbsim_hexarotor_x
  

Problem description

When I launch the simulation:

• The hexarotor spawns already in the sky above Zurich airport
• The vehicle appears ready to arm, but:
  *
  I am unable to arm it
  *
  No proper control response is observed
• It does not start from ground level as expected for a normal takeoff scenario
• and the terminal shows this output while running

Expected behavior

• Vehicle should spawn on the ground (or a defined runway/start position)
• Should allow arming and normal manual/autonomous control
• Standard SITL behavior similar to other JSBSim or Gazebo airframes

Actual behavior

• Vehicle spawns mid-air over Zurich airport
• Arming does not work / fails silently or is blocked
• No meaningful control authority over the vehicle

What I tried

• Rebuilding SITL (make clean + rebuild)
• Re-launching simulation multiple times
• Checking basic JSBSim launch flow

Questions

1. Is this a known issue with jsbsim_hexarotor_x model?
2. Does this airframe require a different startup / launch parameter for ground spawn?
3. Could this be related to missing or incorrect:
   *
   airframe configuration
   *
   home position initialization
   *
   JSBSim initial conditions file?
4. Any recommended fix or workaround to force ground spawn and allow arming?

Additional notes

I am on Ubuntu 24.04, so I also wonder if there are compatibility issues with JSBSim + PX4 SITL on this OS version.

Any help or pointers would be appreciated.

Thanks!