On February 18, 1996, approximately 1630 Pacific standard time, a Piper PA-23-150 Apache, N2237P, sustained substantial damage when it went over an embankment and collided with trees during landing roll at Shady Acres Airport, Spanaway, Washington. The commercial pilot and passenger were not injured. The 14 CFR 91 flight originated at Western Airport, a private airport near McKenna, Washington. Visual meteorological conditions prevailed and no flight plan had been filed. In his report of the accident, the pilot stated: "...approach speed 80 mph...touched down approx[imately] 1/4 way down runway. Yoke full back for aerodynamic braking. Applied full brakes at approximately mid way down runway....aircraft continued at same speed with little or no slowing. [Runway] was wet and it was raining lightly. As end of runway...approached [the pilot] could not see what lay past end of runway. Pilot exited paved runway onto grass with hopes of slowing [and] stopping [the aircraft] over a greater distance. [The aircraft] slowed and in [the pilot's] opinion was only going 10 mph when [the aircraft] went over edge...and dropped approximately 10' into trees." The accident occurred while landing on runway 34, listed in the U. S. Government Airport/Facility Directory (A/FD) as an 1,800 by 20 foot asphalt surface. The A/FD also indicates that runway 34 has a 200-foot displaced threshold, leaving 1,600 feet available for landing. Reference to the owner's handbook for the 1959 PA-23-160 aircraft (according to FAA records, the accident aircraft was a 1956 model) indicated a landing distance of approximately 680 feet at a gross weight of 3,500 pounds, and approximately 600 feet at a gross weight of 3,200 pounds, under the following conditions: standard altitude, flaps down, and temperature 60 degrees F. The landing distance chart in the owner's handbook did not specify whether this represents dry or wet runway performance, and did not contain any correction factors for variations in runway surface conditions. Photos of the airport taken by on-scene investigators, as well as overhead photography in the 1994 Pilot's Guide to Washington Airports (Washington State Department of Transportation), showed a cleared and graded dirt/grass overrun area approximately 600 feet long off the end of runway 34, although this area slopes downward beyond the end of the runway and is therefore not visible from the runway.