The first officer of a Part 91-operated Embraer Phenom 100 told NTSB investigators he noticed a 15-knot tailwind during an instrument final approach to Houston’s Sugar Land Regional Airport on November 21. Although the tailwind decreased to nine knots at the threshold, the aircraft was unable to stop prior to reaching the end of the 8,000-foot runway. The first officer also said he did not observe any standing water on the runway prior to touchdown. Neither of the two ATP-rated pilots, the only two people aboard the aircraft, was injured although the aircraft was substantially damaged. The captain, who was the pilot flying, later reported the brakes were unresponsive after touchdown. She pulled the emergency brakes twice, but the airplane continued past the end of the runway and onto a grassy area, eventually crossing a service road and coming to rest in a drainage ditch with the empennage partially submerged by water.