I sometimes get apnea alerts from the O2D2 unit during flight, even though the cannula is worn correctly and connected fine.
The alarm stops when I move the unit to another place.
I don’t know what causes it, but my guess is that it is caused by some pressure difference, like a ventilator flow in the cabin.
It could also be caused by electromagnetic radiation from the transponder (or another) antenna.
Do other pilots recognize this behavior?