ATLANTA TheStreet) -- A merger pushed the price of AirTran ( AAI) shares up 61% on Monday, but most airline investors are not so lucky. They can only hope for the best in an industry that has lost money since the Wright Brothers first flew an airplane. Some think the historic pattern may be broken, given capacity reductions over the past few years and, so far, an unprecedented level of discipline in maintaining them. The situation has led veteran Avondale Partners analyst Bob McAdoo to issue market outperform ratings on every network airline. But some other evaluations are more discreet. Here is a look at analyst views on the four biggest airlines that will remain following pending mergers that would unite United ( UAUA) with Continental ( CAL) and Southwest ( LUV) with AirTran.