I'm using A3 (Pro) + iOSD MkII + Futaba Transmitter/Receiver

Had a roll over on our initial flight and am trying to figure out why as we are certain everything was correct before takeoff.  Would like to read data but if I understand correctly...

>>the A3 takes data logging away from the iOSD
>>AND...the A3 will only data log IF Lightbridge 2 is installed

so it looks like I have no access to data logging unless I switch to an all DJI system.  

Am I correct?

did you get airborn before the roll or immediately on takeoff

The A3's ability to record flight data will overide the iOSD, so the flight data will still be recorded by the A3. The necessity of the LB2 system would be to have access to the OSD via the Go app, it will not affect the flight recorder.