# PX4 Gazebo mutipledrone problem **URL:** \ **Category:** PX4 Autopilot\ **Created:** [August 10, 2024, 1:47pm UTC](https://discuss.px4.io/t/px4-gazebo-mutipledrone-problem/40143 "2024-08-10T13:47:05Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Ryuu](https://discuss.px4.io/user_avatar/discuss.px4.io/ryuu/32/17021_2.png) [@Ryuu](https://discuss.px4.io/u/Ryuu)\ **Post date:** [August 10, 2024, 1:47pm UTC](https://discuss.px4.io/t/px4-gazebo-mutipledrone-problem/40143/1 "2024-08-10T13:47:05Z")
Hi, i’m using px4 gazebo to simulation drone. i want to spawn 2 drone and do some mission waypoint: i used this command to start the gazebo sim: /Firmware/Tools/simulation/gazebo-classic/sitl\_multiple\_run.sh -n2 -m iris then I open 2 other terminal and start PX4 ./build/px4\_sitl\_default/bin/px4 -i 0 ./build/px4\_sitl\_default/bin/px4 -i 1 i can see 2 iris drone are spawn and then i open QGroundcontrol, it automatically connect 2 drone. I start mission of drone 1. then i switch to the drone 2 but i got the problem that drone 1 got failesaft and return to lanch. ![image](https://discuss.px4.io/uploads/default/original/3X/b/8/b89259436440fe00965bef4ad1110944723e46c8.png) I dont know what is the problem. pls help me ---
**Author:** ![JulianOes](https://discuss.px4.io/user_avatar/discuss.px4.io/julianoes/32/30_2.png) [@JulianOes](https://discuss.px4.io/u/JulianOes)\ **Post date:** [August 11, 2024, 10:12pm UTC](https://discuss.px4.io/t/px4-gazebo-mutipledrone-problem/40143/2 "2024-08-11T22:12:25Z")
Which PX4 version is that? Have you tried reproducing it with this? > **[Failsafe State Machine Simulation | PX4 User Guide (v1.14)](https://docs.px4.io/v1.14/en/config/safety_simulation.html#failsafe-state-machine-simulation)** > > PX4 is the Professional Autopilot. Developed by world-class developers from industry and academia, and supported by an active world wide community, it powers all kinds of vehicles from racing and cargo drones through to ground vehicles and... ---
**Author:** ![Alp\_Ucan](https://discuss.px4.io/user_avatar/discuss.px4.io/alp_ucan/32/22000_2.png) [@Alp\_Ucan](https://discuss.px4.io/u/Alp_Ucan)\ **Post date:** [August 12, 2024, 7:57am UTC](https://discuss.px4.io/t/px4-gazebo-mutipledrone-problem/40143/3 "2024-08-12T07:57:08Z")
May be you can use COM\_RCL\_EXCEPT parameter to avoid trigger failsafe in mission mode. ---
**Author:** ![Ryuu](https://discuss.px4.io/user_avatar/discuss.px4.io/ryuu/32/17021_2.png) [@Ryuu](https://discuss.px4.io/u/Ryuu)\ **Post date:** [August 12, 2024, 11:42am UTC](https://discuss.px4.io/t/px4-gazebo-mutipledrone-problem/40143/4 "2024-08-12T11:42:18Z")
hi, thank you for the support. i tried setting COM\_RCL\_EXECPT and the fail safe warning seem not exsit anymore… however i got this notify from QGC so i cannot arm the vehicle ![image](https://discuss.px4.io/uploads/default/original/3X/6/c/6ce39709fe1c361faad7b4a068e0d56f660f5d52.jpeg) ---
**Author:** ![Ryuu](https://discuss.px4.io/user_avatar/discuss.px4.io/ryuu/32/17021_2.png) [@Ryuu](https://discuss.px4.io/u/Ryuu)\ **Post date:** [August 12, 2024, 11:44am UTC](https://discuss.px4.io/t/px4-gazebo-mutipledrone-problem/40143/5 "2024-08-12T11:44:13Z")
I use PX4 autopilot commit “b6da0b141d9945128bc069a9a5a25f3c3c86893e” ---
**Author:** ![Alp\_Ucan](https://discuss.px4.io/user_avatar/discuss.px4.io/alp_ucan/32/22000_2.png) [@Alp\_Ucan](https://discuss.px4.io/u/Alp_Ucan)\ **Post date:** [August 12, 2024, 2:11pm UTC](https://discuss.px4.io/t/px4-gazebo-mutipledrone-problem/40143/6 "2024-08-12T14:11:49Z")
There may be different problems that cause this situation. You can see the reason from warning tab at left top of the screen like this: ![image](https://discuss.px4.io/uploads/default/original/3X/1/1/11c19251ef4bd94e67a4b2f9aee7b2177fb88e05.png) Something preventing arming. Like high throttle,flight termination or AHRS healthy. Check these flags.