11.   After the small carriers are forced to retreat, the big airlines cut back service and raise prices.

12.   Bush has vowed to prevent big airline strikes this year, and Delta has lobbied for an emergency board if no deal is reached.

13.   But analysts also say big airlines are struggling to maintain unit revenues in the face of plateauing traffic growth.

14.   But he and other veteran travelers worry about the potential for further deterioration in passenger service as big airlines continue to swallow smaller ones.

15.   But pilots at the big airlines are fighting back, he said.

16.   But the big airlines muscled right in.

17.   But Travelocity.com and other online travel businesses are closely watching Orbitz, a planned site backed by big airlines.

18.   But with business air fares soaring nationwide, there is a growing debate under way about whether big airlines increasingly are using their growing market power to hamper competition.

19.   Cruise lines arrange with the big airlines to block a certain amount of space on flights from major cities to their departure points for a year in advance.

20.   Delta and Continental have mostly complementary routes and are lightly unionized compared to other big airlines, making a merger easier in some respects.