Failed to connect to SITL Instance in Mission Planner

I am running Mission Planner 1.3.81

For the last 2 days, When running Mission Planner Simulator, I get error message:
Failed to connect to SITL instance. No heartbeat Packets Received.
I am using Model flightaxis. Is anybody else having this Problem?

Any help will be greatly appreciated.


Hey Randy, are you running the flightaxis sim using another sim software?

I’ve been running it with RealFlight and it won’t connect in missionplanner until it’s established a connection to RealFlight. Usually I’ll start the sim on MP, let it give me that error, wait until it connects on RealFlight, then connect using the TCP function:

Once sim is running, select TCP from the drop-down, enter host (local host) and port 5760 (or whatever is displayed on your sim command-line window).

Not sure if this will help, but that’s what works for me!

Yes I am running flightaxis to run RealFlight. So you have confirmed that RealFlight must be running to establish connection. That is what I was not doing. Thank you so much!

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I still have one little problem. I still get a, Failed to connect to SITL error message when in the Extra command Line, I add,


Does anybody know why that is?

I have figured out the problem. The Entry should be


Now I can connect.