Not fired. The CEO resigned for personal reasons.
Perhaps, but that's usually along the same lines as 'left to pursue other interests.' When it is 'effective immediately' and the new guy has already been picked, it's usually not voluntary.
Media are linking it to the earnings:
AP/Chronicle: "Southwest Airlines CEO and board vice chairman James F. Parker announced his retirement today as the company reported second-quarter earnings fell by 54 percent, missing Wall Street targets.
Parker, whose retirement was effective immediately, said he was leaving for personal reasons.
NYTimes:"Yesterday morning, Mr. Parker notified Southwest's board that he would leave immediately. The airline, which had announced its second-quarter results earlier in the day,"
Mr. Parker, a Southwest executive since 1986, said that his decision to go was prompted by "a combination of things" that he did not specify; he said his health was fine.