Is this bus still in operation and only for AA T3 to BA T5 connecting customers?
What happens if you are on separate records arriving on AA and departing on BA and don't check in online? Will they deny you the ability to use the bus and make you go outside and use the bus?

How about a local ORD customer who prefers the Flagship Lounge at ORD? If you do check in online with BA, will the TSA let you use clear security in the AA Terminal for lounge access?
Could you then take the transfer bus over to T5?

Thanks!