Originally Posted by QueenOfCoach

Welcome to Flyer Talk.

There is only one Citi Aadvantage that offers one free checked bag: The Citi Executive / AAdvantage World Elite MasterCard. It is a new card that was introduced only a few months ago, and costs $450/year.

I'd like to bet your MIL does not have that card. I don't. My Citi Aadvantage card is an older one and does not offer the free checked bag.

You might look into shipping your gear by UPS or other freight carrier. That might be cheaper than paying the checked baggage charges.