emtea, since you had a displayed compass error is it possible you experienced TBE, Toilet Bowl Effect? This is caused be the need for compass calibration The craft will fly like its riding a whirling vortex.
It is my understanding that switching to ATTI mode only helps with GPS and VP control input errors. The "compass" is never disabled.
When researching a compass problem I was told that the "compass" function of the IMU cannot be disabled on the I1. I never found a way to do it.
According to the I1 manual pg. 12, the GPS RTH function is available in ATTI with loss of RC signal. Since you had control via the RC and had a compass warning, I think you had a calibration issue with the compass and/or the entire IMU.
It is my understanding that switching to ATTI mode only helps with GPS and VP control input errors. The "compass" is never disabled.
When researching a compass problem I was told that the "compass" function of the IMU cannot be disabled on the I1. I never found a way to do it.
According to the I1 manual pg. 12, the GPS RTH function is available in ATTI with loss of RC signal. Since you had control via the RC and had a compass warning, I think you had a calibration issue with the compass and/or the entire IMU.