On May 9, 1996, about 0910 eastern daylight time, a Beech A36, N65792, was destroyed when it collided with trees during an instrument approach to the Cattaraugus County-Olean Airport, Olean, New York. The two commercial pilots and three passengers received minor injuries. Instrument meteorological conditions prevailed for the business flight that departed Ticonderoga, New York, about 0700. An instrument flight rules flight plan had been filed for the flight conducted under 14 CFR Part 91. The flying pilot reported that his employer, the right seat pilot, advised him he could join them for the flight and that he could fly from the left seat. The flight departed VFR; however, while en route an IFR clearance was obtained. Radar vectors were requested for the Localizer 22 approach to Olean. The descent was executed in extremely dense fog. The pilot stated that during the final approach, "As I continued to descend to the next phase at 3200 feet, until we passed final approach fix, I started our time to shoot the approach and continued to the DH [decision height] at 600 feet per minute. I continued to make course corrections on final." He then heard the right seat pilot say stick with it, followed by him stating he observed trees. The airplane then impacted the trees. The right seat pilot stated that during the final approach, "The needle on the HIS [horizontal situation indicator] deflected about one-half scale and I told him [the flying pilot] to "Stick With It." We crossed EANEY [initial approach fix] and [the flying pilot] continued the descent. I was monitoring distance to the MAP [missed approach point] and looking outside. I caught a glimpse of the ground and said "I have trees" and I noted that we were about a mile from the airport (MAP). I then glanced at the altimeter and said "No Lower", and was about to call the missed approach when we crashed into trees." Also, he stated that "We should have abandoned the approach early." Examination of the accident site by a Federal Aviation Administration Inspector revealed that the airplane came to rest approximately 600 feet to the left of the runway. Also, examination of the wreckage did not disclose evidence of mechanical malfunction, nor did either pilot report any. The altimeter was found set to 30.18" Hg. According to 14 CFR Part 91, under 91.175, for instrument approaches to civil airports, and operations below DH or MDA, it stated: Where a DH or MDA is applicable, no pilot may operate an aircraft, except a military aircraft of the United States, at any airport below the authorized MDA or continue an approach below the authorized DH unless. . .(2) The flight visibility is not less than the visibility prescribed in the standard instrument approach being used; and (3) Except for a Category II or Category III approach where any necessary visual reference requirements are specified by the Administrator, at least one of the following visual references for the intended runway is distinctly visible and identifiable to the pilot: (I) The approach light system. . .(II) The threshold. (III) The threshold markings. (IV) The threshold lights. (V) The runway end identifier lights. (VI) The visual approach slope indicator. (VII) The touchdown zone or touchdown zone markings. (VIII) The touchdown zone lights. (IX) The runway or runway markings. (X) The runway lights. . . . Hourly weather observations were recorded at the Olean Airport by the airport manager. The 0745 and 0845 observations were indefinite ceiling zero and zero visibility with light rain and fog. Additionally, the flight minimum visibility prescribed for the Localizer 22 approach, at Olean, was 1 mile.