On February 9, 2004, at 1530 eastern standard time, a Cessna 402B, N6387X, sustained substantial damage when it impacted a tree during low altitude maneuvering near Sturgis, Michigan. The pilot rated passenger took control of the airplane and landed without further incident at the Kirsch Municipal Airport (IRS), Sturgis, Michigan. The commercial pilot sustained serious injuries, and the pilot rated passenger received minor injuries. The flight was operated under 14 CFR Part 91. Visual meteorological conditions prevailed at the time of the accident. The flight originated from Battle Creek, Michigan, at 1510 and was en route to IRS. The pilot rated passenger reported that the airplane was about 5 miles north of IRS when the pilot-in-command said that he wanted to fly over a friend's house. The airplane was on a southerly heading and the house was to the left to of the airplane. The pilot-in-command executed a steep left turn for 360 degrees and leveled the airplane just above the tree line. The pilot rated passenger stated that he remembers the pilot-in-command said something like, "This is low." According to the pilot rated passenger, he remembers the pilot responding, "I think someone is home." The pilot rated passenger stated that he and the pilot both looked forward and saw a large pine tree 30 feet ahead of the airplane. The pilot rated passenger reported that the pilot-in-command began to pull up, but it was too late. According to the pilot rated passenger, the airplane struck the pine tree at 170-180 knots. The impact shattered the pilot side window and the left forward baggage door came open. The pilot-in-command remained conscious, but was bleeding from the head area. The pilot rated passenger took control of the airplane and landed without further incident at IRS. The pilot rated passenger reported that neither he nor the pilot-in-command were using their shoulder harnesses at the time of the accident. The Federal Aviation Administration's Advisory Circular (AC) number 91-65, "Use Of Shoulder Harness In Passenger Seats," was released on August 4, 1986. In the AC it is reported that the National Transportation Safety Board examined 500 relatively severe general aviation airplane accidents to determine what proportion of the occupants would have benefited from the use of shoulder harnesses. The AC states, "The [national transportation] safety board found that 20 percent of the fatally-injured occupants in these accidents could have survived with shoulder harnesses (assuming the seat belt was fastened) and 88 percent of the seriously injured could have had significantly less severe injuries with the use of shoulder harnesses."