California shooting shows security vulnerabilities on buses

Would-be plotters bent on staging an attack aboard a passenger plane know they've first got to pass through a gauntlet of security measures at an airport, from body scans and spot interrogations to pat-downs and even close scrutiny of their shoes.The comparative scant security prompted at least one survivor of Monday's shooting on the bus heading from Los Angeles to San Francisco to rethink his future mode of travel.“I think I will just fly from now on," Mark Grabban said.