Rob Lowe kept his cool during strong turbulence on a flight from LA to New York the other night. The “Brothers and Sisters” star was traveling with his 18-year-old son, Matthew, in first class on Virgin Airways. In the middle of helping his son, who is interning in House Majority Leader Eric Cantor’s office this summer, with some work, the extremely rough ride distracted both of them, but sent other passengers into a panic. “People were screaming. It was that bad, but Rob kept his cool,” a spy said. After the safe landing, Lowe went to the cockpit to thank the pilot. He took photos and signed an autograph. A rep for Lowe confirmed the incident.