It’s not always better to sit in the front of the plane. The first class cabin on a star-studded United flight from New York to Los Angeles filled with smoke yesterday when a cockpit fire forced the pilot to make an emergency landing at Dulles Airport. The plane landed safely outside of Washington, D.C., and the flames went out before the wheels even touched down. The Hollywood circuit is breathing a collective sigh of relief because Ashley Olsen (of “Full House” fame); her boyfriend and The Hangover start Justin Bertha; Jersey Boys’ Jarrod Spector; and Pamela Adlon from Showtime’s “Californication” were all en route to the Golden State on the same flight. Officials don’t know what caused the fire, but the National Transportation Safety Board is investigating to determine if the same window heating problems that caused fires in 29 other Boeing 757 jets are to blame for the flames.