On December 28, 1995, at 1758 eastern standard time, a Cessna 210, N450EM, exited the right side of runway 33R during the landing roll and came to rest in a ditch at Baltimore-Washington International airport (BWI), in Baltimore, Maryland. The certificated private pilot and the two passengers reported no injuries. The aircraft sustained substantial damage. Visual meteorological conditions prevailed for the flight that originated in Caldwell, New Jersey, at about 1700 eastern standard time. The flight was operated under 14 CFR 91, no flight plan was filed. The pilot reported that he landed on the main landing gear, then the nose gear. The pilot stated he then heard a thud, felt the aircraft shudder, swerve left, and then exit the runway on the right side. A captain of the BWI Fire Department stated that when he arrived on the scene the nose gear appeared to be down and locked and that both main landing gear "...were in the well." The captain further stated that when the aircraft was raised to be placed on a dolly the right main landing gear kept flopping out but that the left main landing gear remained in the well. The pilot reported no mechanical problems with the aircraft prior to the accident. The passenger in the right front seat of the aircraft reported that he heard a steady "...beep...beep...beep..." throughout the approach and "...until we landed." The front seat passenger described the landing as "very smooth." He stated that the aircraft touched down "tail first with the propeller touching very soon after. We went up in the air for a little while then came back down. We slid for only a few yards after that. I didn't know we crash landed until I saw the propeller tips bent back." Cessna Airplane Company personnel reported that the aural landing gear warning is an intermittent horn, which sounds when the airplane is operated with the master switch on, the throttle closed, and the landing gear is not extended. Federal Aviation Administration (FAA) and National Transportation Safety Board (NTSB) personnel participated in the postaccident examination of the aircraft. Inspection and functional tests of the landing gear system revealed that the landing gear was in good working condition and showed no evidence of foreign object damage. The landing gear moved smoothly through the full range of travel and locked fully in both the retracted and the landing configuration. Additionally, the gear was extended by the emergency extension hand pump with no problems noted.