(09/24/1999) -- From the Shuttle Landing Facility, the orbiter Columbia leaves Kennedy Space Center on the back of a Boeing 747 Shuttle Carrier Aircraft on a ferry flight to Palmdale, Calif. Columbia, the oldest of four orbiters in NASA's fleet, will undergo extensive inspections and modifications in Boeing's Orbiter Assembly Facility during a nine-month orbiter maintenance down period (OMDP), the second in its history. Orbiters are periodically removed from flight operations for an OMDP. Columbia's first was in 1994. Along with more than 100 modifications on the vehicle, Columbia will be the second orbiter to be outfitted with the multifunctional electronic display system, or 'glass cockpit.' Columbia is expected to return to KSC in July 2000