Originally Posted by
zombietooth
Possibly related: When I booked the O fare itineraries to Tokyo, I was given immediate UGs to domestic F on the connectors. So does booking O give one access to PN inventory and is it equivalent to the Y/B/M UG mechanism?
Not exactly. O/A/R all delegate to B on aircraft without a PE cabin. So you got access to PN, not because O/A/R are included in the instant upgrade system, but because you were in B on those legs.