On October 17, 1998, at 0033 central daylight time, a Beech 65-B80, N138BA, registered to Bemidji Aviation Services, Inc., of Bemidji, Minnesota, and operated by an instrument rated commercial pilot, sustained substantial damage when it impacted the terrain one-quarter mile short of runway 23 at Brainerd, Minnesota. The pilot who received minor injuries reported that his attention was diverted during the approach and the airplane accident occurred in a controlled descent into the terrain. The flight was operating in instrument meteorological conditions on an IFR flight plan. The 14 CFR Part 91 positioning flight departed Minneapolis, Minnesota, at 2355 on October 16, 1998. In his written statement, the pilot said that when he reached the point he thought he should be seeing the approach lights, he checked the radio to determine if it was on the correct frequency. He said that he realized that the transmit switch was selected on the wrong radio and when he returned his attention to the instruments he realized that he had allowed the airplane to descend below the glide path. He said before he could react, the airplane impacted the terrain.