A passenger on a USAir flight Saturday from San Diego to Pittsburgh tried to open cockpit and outside doors before flight crew members subdued him, authorities said. Kenneth Conrad Swanson, 24, of San Diego was arrested and booked on suspicion of a felony--assaulting, intimidating, threatening and interfering with a flight attendant, said Max Geiman, a spokesman from the FBI's Kansas City office. Swanson was released Monday morning on a $5,000 bond. "From the acts he accomplished, the passengers were in no danger," said Geiman. "The most he achieved was setting off an alarm that showed somebody was tampering with the door."