LOT Polish Airlines Boeing 767-300 flight 16 from Newark NJ to Warsaw Poland with 220 passengers and 11 crew, was on approach to Warsaw's runway 33 when the crew aborted the approach at 3000 feet reporting an unsafe landing gear indication for all three landing gear struts. The aircraft entered a holding pattern to troubleshoot the problem for about 75 minutes. Visual verification by F-16 aircraft showed none of the landing gear was down and attempts to lower the gear alternatively failed. The jet landed on its belly in Warsaw after its landing gear failed to retract, triggering sparks and small fires. About 30 minutes after departure from Newark the crew reported the failure of the center hydraulic system.