Machinbird
Care to elaborate a bit?
Were you the oscillator or the oscillatee?
I was an interested "bystander/bysitter" ....but not for long
Can't say much...but
FWIW, me PM, PF is handflying. On final the aircraft starts abruptly oscillating in roll...Your's truely thinks "WTF" ? Wake vortex/Flight Control problem? Are we controlling the aircraft or not? ... I then
see, out of the corner of my eye, the magnitude and phase of the control wheel inputs being applied....
Seeing the control wheel fully over with the aircraft already rolling back through wings level and heading towards the control input is a heck of a stimulus/big clue, even I can pick that one up... Roll inputs terminated..
Aircraft stops oscillating and subsequently lands OK.
FDR trace examined by various interested parties. PIO most definitely diagnosed.
Now I'll admit to being an ex "basic" QFI which kind of also colours my POV but there's no doubt in my simple mind that being able to see your colleagues control inputs and see/feel the aircraft's response to the same might sometimes be of just a little use.....
, but having never flown an "A" I'm not really able to objectively enter the A vs. B debate...