United ended up delivering the bag the next day, American said. It is common practice in the airline industry for the last carrier to transport a passenger on a leg of their trip to look after that customer and to locate and deliver bags regardless of which airline lost the bag.
United is not a party to the lawsuit and declined to comment.
"In her last conversation with American Airlines ... she was told nothing could be done," the lawsuit said.
The airline refused her demand for a refund of the baggage fee, the suit said. American said such a claim never was filed.
According to court papers, Covarrubias isn't alone: American Airlines damages, loses or delays more than 2,400 pieces of luggage every day. The Department of Transportation says that American and American Eagle mishandled 30,223 bags in October, the last month available. That's 975 bags a day.
"American Airlines is just another example of how companies have forgotten about customer service," Covarrubias said in a statement released through her lawyers. "When American charges a fee for a baggage service it should deliver your bag, unharmed, or give you a refund."
In a bid to increase revenue, American Airlines took what it called the "extraordinary measure" of charging baggage fees in 2008, the lawsuit said. It charged a fee of $25 for the first checked bag, $35 for the second, $100 for the third, fourth and fifth pieces, and $200 for every bag thereafter.
All the major airlines except Southwest and JetBlue now charge for the first checked bag -- United Airlines was tops in bag fees, raking in $400 million last year from them.
The fees, the lawsuit said, represented a "clear and unambiguous agreement with passengers to handle bags with care, and deliver them to their destination in a timely fashion."
While the majority of checked bags reach their destination without incident, a total of 2,193,711 bags were reported mishandled by airlines last year in the United States. American Airlines was second on the list with 299,257 reports; Southwest Airlines led the pack with 357,525 reports.
Passengers can claim a maximum liability of $3,300 for domestic flights should checked luggage be lost in transit. International limits are lower, roughly $100 for every 2.2 pounds of luggage, for a maximum total of $640.
Travelers can buy excess valuation for luggage as secondary insurance. A dollar buys $100 worth of extra insurance on domestic flights, with a ceiling of $17 for $1,700 in coverage.
Airlines are required to reimburse passengers for clothing and toiletries in the event of a lost or delayed bag, according to the U.S. Department of Transportation. But getting the cash back can take considerable time.
Many airlines' contracts of carriage between carriers and passengers don't specify clothing reimbursement in detail, but standard DOT policy demands they provide some compensation.
Hobica said it's often more reliable and cheaper to send your luggage out ahead of time -- by courier.
"I sent an envelope via FedEx ground and they misdirected it and they gave me an automatic $100 check without even asking," he said. "I always tell people: Send your bags by FedEx ground. It's cheaper and they have more accountability."