CappuccinoAddict

It makes all the difference. *G are allowed to use business class lounges within the alliance at any point of an international journey. Non-*G passengers, however, can only use UA lounges at departure airports of international flights and only when seated in a premium cabin. I believe connecting airports are OK too, but only if it is prior to the international leg. For instance, if flying BOS-hub-EU/Asia/S America etc in J, you could use the UC at BOS and at the hub. Doesn't work the other way around. That being said, might as well try your luck and see.

ORDnHKG

I am not sure what airport lounge "Flipping the boarding passes work all the times for me" ? You get access when you are arriving international is because you are UA*G.

UA lounge agent would care less if you are arriving any non UA international F or C, all they care is either you are UA*G, or if you are arriving UA metal, but neither apply to OP, which means no lounge access.

Even you are connecting to F on a 3 class you still have no F/Polaris lounge access as long as it is domestic, as domestic no matter you are F on a 2 class or F or a 3 class makes no difference, as domestic = no lounge access period !

You probably don't know once I had arrived SFO in SQ F, even SQ SKL in SFO denied me as stating I am arriving not departing international !


You got lounge access is only because of that.

Guava

Officially, the lounge access is only for the departing airport of the said international flight in premium cabin. *A rules do not grant lounge access for a connecting airport to the said international flight, which means under this scenario, someone without *G status would not be able to use the UC at BOS.

Lounge access within *A are strictly governed by the cabin of the flight you are going to board at the said airport or elite status unless the airline in question has their own in-house rules, which then fall outside the jurisdiction of *A.

People often confuse *A lounge access with the more simplified and generous OW lounge access so it's important to understand the two set of rules are very different.