Columnist Scott McCartney says that air travel appeared to be stabilizing after years of service cuts, wide-ranging fees, security hassles and the occasional lengthy tarmac delay. Then, the Pants Bomber struck, or attempted to strike. In the near term, new security issues will be in force, prompting long lines, invasive searches and other hassles. Once the initial frenzy passes, the Transportation Security Administration, Federal Aviation Administration and airlines need to make some concrete changes. McCartney offers some ideas.