Did you have a good weekend? I'll bet Delta Air Lines, United Airlines, and American Airlines had a better one.

Because while you were enjoying time with friends and family or maybe just enjoying the weather, Congress was busy handing the airlines a massive legislative victory--one that could easily be worth billions of dollars.

( Update : After this article was published, we had the chance to pore through the analysis of this 1,200-page bill. There's a lot more even than this one multi-billion-dollar issue. Besides the decision not to regulate change fees and baggage fees, there are at least 17 significant changes to airline travel coming as a result of the bill. You can read about them all here.)

It all comes as part of the authorization bill that keeps the Federal Aviation Administration running, and that Congress has to pass by the end of the month.

Some senators on both sides of the aisle were reportedly trying to use the bill to limit how airlines to charge passengers to to change reservations.

And after a Senate version of the bill included a provision to limit change fees, the big airlines and their lobbying group, Airlines for America, pushed hard to stop it. The reason is simple: It's big business for the airlines, with some charging $200 or more to make a change, not including any difference in fare.

As you might have experienced yourself, those fees can lead to passengers simply discarding a reservation they can't use, because paying the change fee would cost more than a brand new ticket.

Add it all up, and it's about $3 billion or more annually across the industry. American Airlines alone made $878 million from change fees last year, which adds up to about 2 percent of its revenue, according to The Wall Street Journal.

"It is our top priority to ensure that this--what we consider an existential threat to our business--does not become law," Sharon Pinkerton, the lobbying group's senior vice president for policy, told the Journal a few days ago.

Even Southwest Airlines, which doesn't actually charge change fees, didn't want Congress getting involved. They believe their they have a big competitive advantage, and they they don't want the other airlines to change their policies--or to be forced to do it by Congress.

But on Saturday, just a little over a week before the Sept. 30 deadline to pass a bill, it looks like the airlines won the battle. As the Journal reported:

A version of the FAA bill released on Saturday doesn't include a provision that would have given the Department of Transportation oversight of the fees airlines charge passengers to change their reservations, according to a summary of the legislation and to spokesmen for the House and Senate transportation committees.

Airlines generally like change fees, along with fees for checked baggage, carry on luggage, and virtually everything else you can think of, for two reasons.

First, fees don't show up normally when passengers comparison shop for low fares. And second, because unlike airfare itself, fees aren't subject to federal taxes.

"Congress had the opportunity to return fairness to change and cancellation fees," Sen. Edward J. Markey, who has been the main leader on the issue, told the Journal. "No one should have to pay a $200 change fee on a ticket that costs nearly that much."

Markey is a Democrat; the Journal reports Sen. Roger Wicker of Mississippi, a Republican, also was pushing for limits on change fees.

In Washington right now, political attention is focused on other things, like the Supreme Court nomination battle and the China trade war. And so the airlines score a big win.