CHARLOTTE ( TheStreet) -- US Airways ( LCC) finished last among the five biggest airlines in a recent survey of customer satisfaction with their mobile apps and Web sites, which is not surprising given that US Airways is the only major airline without an app for its passengers. At one time the carrier was saying an app would be available late in 2012, but now spokesman Davien Anderson said the rollout will occur sometime in 2013. He declined to be more specific. "We are in the process of launching an app," Anderson said. "We've been working hard to make sure that it is competitive with what other airlines have. We want to be sure we are giving out customers the best." In the meantime, US Airways on March 4 launched support for Apple Passbook, a "virtual wallet" app, that allows passengers to store material such as merchant cash cards and mobile boarding passes. Passbook eliminates the need to go to one's email when searching for a mobile boarding pass, but it is only available on Apple ( AAPL) phones. The survey by ForeSee, an Ann Arbor, Mich.-based data analytics company, ranked customer satisfaction with mobile apps and Web sites for 25 top travel companies. Southwest ( LUV) ranked highest among all travel companies with a score of 82 out of a possible 100. After Southwest, the next seven companies were either hotel or car-rental companies, all of which ranked above the average score of 77. US Airways ranked last among the 25 companies with a score of 74. American ( AAMRQ.PK) and Delta ( DAL) each scored 77 while United ( UAL) had a 75. ForeSee noted that 33% of airline passenger mobile users prefer to use an app over a mobile site. ForeSee said it conducted an online survey of 6,000 people who said they had used one of the company's appS or mobile siteS. The firm said that Southwest's superior score "could be the result of the utility and simplicity of the airline's mobile site and app from both the usability and informational standpoints." One advantage seems to be that since Southwest does not generally offer assigned seating and does not charge for baggage, it is "able to streamline its mobile experience, alleviating much of the minor headache and confusion that goes along with some of the more traditional airline mobile sites."