THE PLT WAS AT A CRUISE ALTITUDE OF 4000 FT., EN ROUTE TO READING. HE WAS ISSUED A CLEARANCE TO EXECUTE THE ILS APPROACH TO RWY 36. AT THE TIME THE PLT RECEIVED THE CLEARANCE, HE WAS AT 4000 FT. AND 3 MILES FROM THE OUTER MARKER (LOM). THE LOM IS LOCATED 3.9 FROM THE END OF RUNWAY 36 AND THE GLIDESLOPE INTERCEPT ALTITUDE WAS 1636 FEET MSL. APPROXIMATELY 7 MINUTES AFTER ACCEPTING THE APPROACH CLEARANCE, THE PLT CONTACTED ATC AND STATED HE WAS EXECUTING THE 'MISSED APPROACH.' THE WRECKAGE WAS LOCATED IN MOUNTAINOUS TERRAIN, AT AN ELEVATION OF ABOUT 1,100 FT, APPROXIMATELY 13 MILES NORTH OF THE AIRPORT. BASED ON THE LAST RECORDED GROUNDSPEED OF 174 KNOTS, THE AIRPLANE WOULD HAVE TRAVELLED APPROXIMATELY 20 NM FROM THE TIME THE PLT RECEIVED THE APPROACH CLEARANCE (6.9 NM FROM THE AIRPORT) TO THE TIME HE BEGAN TO EXECUTE THE MISSED APPROACH.