On Sunday, August 29, 1993, at about 1600 eastern daylight time, a Piper PA-28-161, N2572U, piloted by Mr. Patrick Flannery, departed the end of the runway during the landing roll at the Allegheny County Airport, West Mifflin, Pennsylvania. The airplane was substantially damaged. The pilot was not injured. Visual meteorological conditions prevailed at the time and no flight plan had been filed. The flight was being conducted under 14 CFR 91. The pilot said he had just touched down on runway 23, and "...decided that my speed was too high and that a go- around would be appropriate." The pilot added power, retracted the flaps and before he could call the tower he noticed, "...what I believed to be a helicopter at low altitude in close proximity to my left...moving in the direction of my planned flight path." The pilot then attempted to stop the airplane, but he said. "...I reached the end of the runway...but could not stop before running off the runway." According to FAA Inspector, Dennis Ferencz's report: ...the aircraft...slid off the end of the runway and came to rest at the bottom of an embankment...it appeared that the aircraft landed at a point approximately 1934 feet past the approach end of the runway which is 2534 feet long. This was apparent by the black skid marks that began at this point and continued for approximately 600 feet to the end of the runway. At the end of the runway is an embankment which drops down approximately 12 feet... According to FAA Inspector, Dennis Ferencz, the pilot told him after the accident that he was high on the approach and had to lower the nose of the airplane to make the runway. In a memo to the Safety Board Mr. Ferencz wrote: ...N2572U landed long on runway 23...control tower personnel state that N2572U touched down at a point between runway 10/28 and taxiway "A"...approximately 650 [feet] from the departure end of runway 23...