GPS issues with no GPS connected

Hi Community,
I’m trying to set up a quadplane as part of a school project using a pixhawk as the flight controller but I am having trouble arming it. I’m using APM Planner 2. When I connect the flight controller to my pc via USB and press the arm button a red error comes up on the screen stating “FAILURE: Failed CMD: 400”

When looking into the log I get the messages “Prearm: AHRS not Healthy” and “Prearm: Bad GPS position”

I am unsure what to do about this as I have no GPS module connected to the pixhawk as I assumed that I would not need it and that it was an optional extra. Is this the case? and I am unsure what to do regarding the AHRS not healthy message, my research has lead me to something to do with EKF settings which may be linked to GPS use which, as I said, I do not have.

Thanks for your help guys, it’d be great to get this working, feel free to ask any questions and request any information that may help you diagnose an issue.

I’m very new to ardupilot and autopilots in general, I have experience flying quadcopters and manual aeroplanes so tuning drones in Betaflight is about as far as my technical knowledge of programming aircraft goes.

Thanks once again.

What is a “quadplane”?

Not an optional extra apparently.

Thanks, I saw that when i was researching what to use but obviously i have misinterpreted it.

Effectively this.