Personal information for more than 8,000 applicants to become pilots at American Airlines and Southwest Airlines was stolen when hackers broke into a data base maintained by a recruiting company. According to letters that the airlines were required to file with regulators in Maine, hackers gained access to names, birth dates, Social Security and passport numbers, and driver and pilot-license numbers of applicants for pilot and cadet jobs. According to filings, 5,745 applicants to American and 3,009 at Southwest were affected, many of whom were hired by the airlines.