Risks of Compass-less Operation (GSF)

ArduCopter Copter 4.3
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I’d like to disable the compass on my copter to bypass EMI issues to fly in stabilize mode (per GSF). I still have a GPS that locks. If I hit a failsafe (low battery voltage for example) and it’s set to RTL, will the vehicle still RTL ok without a compass?

In general, I’m trying to understand any other potential risks so that I can set up failsafes correctly.

I’ve set up compless-less operation per GSF by setting COMPASS_ENABLE = 0 and EK3_SRC1_YAW = 8 per Compass-less Operation — Copter documentation

Note that I’m working to resolve the EMI issues, but until then looking to validate the vehicle config with some simple flights.

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A flight with lots of yaw, circles and a figure-8 then some Magfit work on the log and the compass should operate quite well.
If the GNSS unit has a compass in it that should be fine with normal calibration - or get it up higher away from batteries.

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Thanks for the suggestions. I’m having trouble doing the mag fit flights - see Crash due to Err:GPS and Err: EKFCHECK-0 for info on the crash that happend. I’m pretty limited on packaging so trying to get away with the location I currently have. Going to try to shield all cables

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Replied in that other discussion

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Hey Shawn I’m trying to better understand the risks of flying in stablize mode with the compass disabled in GSF.

Is it that in the event of a failsafe, the copter may not be able to navigate home if there is a poor GPS lock (failsafe action set to RTL)?

It’s my understanding that even in compass-less operation, the yaw alignments will still be made to counter gyro drift using GPS in GSF mode. So seems like another risk may be loss of control due to unwanted yaw changes resulting from poor GPS quality.

Is this assessment correct or am I missing something else?