I reported this error to the author of Aircraft Realism, but according to them the problem is with AAI and Aircraft-Space-Age, so you get a copy of the error message.

The mod Aircraft Realism (2.0.2) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event AircraftRealism::on_tick(ID 0)
AircraftRealism/logic/planeController.lua:144: Old plane does not have
same number of guns as new plane. Check plane prototypes
stack traceback:
[C]: in function 'assert'
AircraftRealism/logic/planeController.lua:144 in function 'transitionPlane'
AircraftRealism/logic/planeController.lua:459 in function 'checkTransitionTakeoff'
AircraftRealism/logic/planeController.lua:471 in function 'updateGroundedPlane'
AircraftRealism/logic/planeController.lua:536 in function 'handler'
AircraftRealism/logic/planeController.lua:48 in function
<AircraftRealism/logic/planeController.lua:40>

Pastebin link to the Factorio log https://pastebin.com/cuiZjEfQ

--The cause is because another mod changed the number of guns in the planes - "Old plane does not have same number of guns as new plane".
You will have to ask the Aircraft-space-age mod author regarding this, the offending mod is probably AAI.-- haih_ys

Thank you for letting me know. My first guess as to what is causing this issue is that AAI reduces the number of weapons in AI vehicles down to 1 per vehicle, and when registered aircraft takeoff, the aircraft is changed from a non-ai plane to an ai plane, and the change in weapon counts causes AircraftRealism to throw an error. I believe it might be possible to fix this issue within AircraftRealism by duplicating aircraft registrations for every registered aircraft that has an AI variant, but I'm not familiar enough with AircraftRealism's code to know exactly how to do that. This is an issue worth fixing, but it might take a while.

This error is likely because the Aircraft mod loads first and creates the grounded/airborne plane prototypes. Then, AAI loads and changes the guns in the grounded prototype only. Then, when you try to takeoff AircraftRealism notices gun counts are different and gives that error.

You can try changing the mod dependencies to make AAI modify the plane first before you copy for the airborne prototype