After cost overruns, a series of delays, and almost a decade of hype, the F-35 Lighting finally performed a vertical landing for the first time. Yesterday at 1 P.M., after descending from a 150-foot-high hover, the test plane touched down on the tarmac at the Patuxent River Naval Air Station. This is a significant step forward for the F-35, as its vertical takeoff and landing capability are crucial to the fighter's role as a replacement for the aging Harrier jet.