About 3,000 to 4,000 peopleare expected for Open Cockpit Day on Sunday at Castle Air Museum in Atwater. The event runs from 9 a.m. to 5 p.m. at the museum, 5050 Santa Fe Drive. About 35 of the 60 vintage aircraft will be open for viewing, and the plane that once flew as Air Force One will be on display. Flight simulators will be operating, and there will be helicopter rides, a bounce house, aircraft models for children to make, law enforcement displays and radio-control aircraft exhibits. A Memorial Day weekend Open Cockpit Day has been running for 18 years and a late-summer event was introduced six years ago, organizers said.