DALLAS (AP) — For a second straight day customers of Southwest Airlines ran into problems Tuesday when trying to use the airline's website to manage their travel plans.

Southwest posted an apology to customers who were having difficulty on the website or the carrier's mobile app. Some customers said on Twitter that they were unable to check in online for flights.

A Southwest spokeswoman said the airline fixed a broken link in customer emails that led to check-in problems, and the airline removed the apologetic advisory from its website around midday.

On Monday, the Southwest spokeswoman blamed difficulties in making or changing reservations on a problem with the airline's new reservation system, which uses information technology from Madrid-based Amadeus IT Group.

An Amadeus spokesman said some airlines' booking capabilities were affected Monday but the problem was fixed and systems were operating normally Tuesday. British Airways and Lufthansa, both Amadeus customers, told The Associated Press that they had not experienced new problems on Tuesday.

Earlier this year Southwest became the first of the four biggest U.S. airlines to use Amadeus's reservations-system platform, called Altea.