Can't Arm when Copter at an Angle

ArduCopter Copter 4.0
1

I need to be able to arm my copter at any angle.
Years ago, I changed a parameter to allow it. Never thought about it again.
Until yesterday when I crashed, and was trying to arm while upside down so I could hear the props and find the copter… And for some reason, not sure when the change occurred, I can no longer arm upside down. I forget the exact error, as I was in panic mode, but something like “prearm:copter leaning”.

I haven’t crashed and had to find a lost copter in probably a year, but I know I was able to in the past. I’m not sure what changed.

What parameter controls the ability to arm while at an angle?

2

I don’t know the parameter but you could disable arming checks for one time.

3

It may be safer to use the blheli feature. They can set to start beeping after a given time of zero throttle.

4

I didn’t have a GCS in the field.

And just in case people are wondering why I don’t use a buzzer or more traditional method, it’s a tiny 120g copter, and a buzzer doesn’t fit.
And while the blheli beeping is a good idea, and would have saved me this time (if I didn’t find it before they started beeping), I also use this to get my copter out of trees… I could be stuck on a branch, hanging off a prop or something, and then arm and be able to move the props enough to break free from the tree.

I used to crash constantly years ago, get in trees constantly, and most definitely could arm at any angle in the past… I don’t think I changed any settings related to it. I vaguely remember setting it in the past, and had to set the angle to something like 180 ior 360 to allow arming upside down… I just don’t see anything like this in the parameters anymore.

5

Well, looking at the code, it looks like it has been set by angle_max for quite some time, which I know has always been 8000 (80 degrees) for me. And it’s one of the INS parameters… So maybe I had simply disabled the INS arming check, and re-enabled it at some point this year.
Might have been thinking about betaflight where I set the arming angle to 180 or 360 degrees, because I was flying betaflight a couple years ago, too.