Although I have been *G for years, I still have not figured how the opcost is worked out among the *member airlines.

Suppose I am Air Canada top-tier flyer, owning a *gold card on Aeroplan. When I travel United, and use its Red Carpet Club in Chicago O'hara, who is paying the cost of me using the RCC?

If again I connect Tokyo Narita on United, I instead use All Nippon Airway's lounge with *Gold, ANA lounge agent records my United ticket and my Aeroplan *G membership card, I assume ANA will send a bill to either United or Air Canada, will it?

This part of the business operation has not worked out on my mind.

Much appreciate your enlightenment.