I travel infrequently by airplane. Today I was flying from Indiana to Virginia on American Airlines and I checked in online before leaving for the airport in Indianapolis. American Airlines would NOT allow me to pay for checked baggage online, I could only pay for checked baggage at the ticket counter at the airport. I asked half a dozen AA employees why they have this policy and nobody knows. Does anybody know why AA has this policy while other domestic airlines let you pay for the baggage when checking in online?