21.  United Air Lines depends on ticketless travel in its new West Coast shuttle service and is using it in business-class service on eight other routes.

22.  Valujet and Southwest were among the first airlines to use ticketless travel.

23.  Passengers can also arrange their own ticketless travel through a Web site, www.jetblue.com.

24.  The airline also will test ticketless travel on some routes, its product development manager, Ng Sui Guan, was quoted as saying.