Airline travelers looking to save money have a couple of reasons to cheer and one cause to grouse.

The good news is that airlines in the U.S. are setting aside more seats for travelers wanting to redeem loyalty reward points. Also, airfares to Mexico and Central America have dropped sharply since Southwest Airlines began selling tickets to those destinations, forcing competitors to match the lower fares.

The bad news is that federal officials now say airlines that offer super­cheap fares by mistake are not required to honor the deals.

A survey to determine the availability of seats for loyalty rewards members concluded last week that U.S. carriers are increasingly generous with rewards seats. For example, when survey takers made online requests for seats for rewards club members on Alaska Airlines, they found seats available 80 percent of the time, up from 58.6 percent of the time last year.

The increased number of seats may show that airlines are trying harder to keep loyal customers happy, said Daniel Farrar, chief executive of Switchfly, a company that develops software for airline and hotel loyalty rewards programs. “The key takeaway is that airlines can’t afford to allow a single customer to have a bad experience,” he said.

Switchfly commissioned the survey.

For travelers planning to vacation south of the border, an analysis by the travel website FareCompare.com found that fares to vacation spots such as Cabo and Cancun, Mexico, have dropped more than50 percent since low-fare carrier Southwest recently announced new routes from Houston to Mexico and Central America, starting in October.

FareCompare Chief Executive Rick Seaney attributed the drop to “good-ol’ competition.”

But if you find a super­low fare that was the result of a mistake by the airlines, the U.S. Department of Transportation issued a temporary ruling saying airlines do not have to honor those prices as long as they reimburse the out-of-pocket expenses of travelers who bought those fares.

Airlines routinely make errors on fares but they retract only the most egregious mistakes to save on the administrative cost of canceling hundreds of tickets, said George Haskell, of FlightFishing.com, a travel website that monitors such mistakes.

Hugo Martin, Los Angeles Times