UPS flight 5X61 suffered a runway excursion and nose gear collapse in a takeoff accident at Seoul-Incheon International Airport (ICN). The aircraft, an McDonnell Douglas MD-11F cargo plane was bound for Anchorage, Alaska. The aircraft’s takeoff weight was 629,600 lbs, which was below the maximum allowable take-off weight of 630,500 lbs. The flight was cleared for takeoff from runway 33L. The aircraft reached V1 speed after a ground run of 6413 feet. About that time the crew heard a noise, originating from the failure of the no.9 tire (the left-hand tire on the central landing gear). The no.10 tire on the same landing gear also ruptured. Vibration and torsion forces then caused the lower drag brace of the central landing gear to break. The drag brace then hit the body several times. This caused a rupture of the hydraulic system of brake system 1, reducing the total brake efficiency to about 48% as the crew rejected the takeoff. With 4,635 feet of runway remaining the aircraft began to decelerate. The aircraft required a deceleration distance of at least about 5,550ft from the position where the takeoff was rejected. As a result, the MD-11 stopped at approximately 1,591 ft (485 m) past the end of the runway 33L. The nose gear collapsed and the no. 1 and 3 engines contacted the grass. The ARAIB investigators noted that there is an inherent difficulty in determining the flight performance of an aircraft after V1 when limited information and little time is available to the crew for a go/no-go decision. The UPS flight operations manual states that after V1, rejecting takeoff is not recommended unless the captain judges that aircraft can not fly, but the manual does not establish a definition of ‘non-flying’. ARAIB notes that it would be beneficial for the aviation industry to provide flight crews with definitions of ‘non-flightability’ and additional guidance and training as to how to judge aircraft flight performance under certain circumstances, especially after V1. CAUSE (translated from Korean): After the take-off determination speed (V1), the high-speed takeoff abandonment is performed by the tire of the central landing gear and the drag brace defect, and the runway is separated. Contributing factor is ” (1) For limited time and available information on the encountered situation, (2) Dynamic instability of dragging of central landing gear after tire failure. (3) Decrease in braking performance due to rupture of hydraulic pipe of brake system 1 “.