Swearingen SA227AT Merlin IVC

The airplane departed New Orleans-Lakefront Airport on a cargo flight to Waukesha, carrying three crew members and a load consisting of 53 dogs in dog crates. On final approach to Waukesha Airport, the crew encountered marginal weather conditions with limited visibility due to snow falls. The airplane crash landed into the third hole on the Western Lakes Golf Course located about 5,5 km short of runway 10 threshold. The airplane slid on its belly for few dozen metres on a snow covered ground before colliding with trees. There was no fire. All three crew members and all 53 dogs were uninjured. Both wings were severely damaged due to the collision with trees.

The pilot, who had more than 3,340 hours of pilot-in-command time in the make/model of the accident aircraft, and was very familiar with the destination airport and its ILS approach procedure, departed on a cargo flight in the SA227 turboprop aircraft. The aircraft was dispatched with the primary (NAV 1) ILS receiver having been deferred (out of service) due to unreliable performance the evening before the accident, thus leaving the aircraft with the secondary (NAV 2) ILS receiver for ILS use. The pilot arrived in the destination terminal area and was given vectors to intercept the ILS localizer, and radar data showed the aircraft intercepting and tracking the localizer accurately throughout the approach. Mode C altitude readouts showed the aircraft approaching from below the glideslope at the required intercept altitude of 4,100 feet, passing through and above the glideslope and then initiating a relatively constant descent, the angle of which exceeded the glideslope angle of -3.5 degrees. Weather at the destination airport was 400 foot overcast and the decision height for the ILS/DME runway 21R approach was 270 feet. The aircraft passed through the tops of trees in level flight about 530 feet above the airport elevation and slightly under 3 nautical miles from the runway threshold. The pilot was given a low altitude alert by the tower and acknowledged, reporting that he was descending through 2,800 feet, which was confirmed on the mode C radar readout. At that point the aircraft was well below the ILS glideslope and about 13 seconds from impacting the trees. Post crash examination of information captured from the left and right HSI units and an RMI revealed that the NAV 1 receiver was most likely set on the ILS frequency, and the NAV 2 receiver was most likely set on Spokane VORTAC, a terminal navigation facility located very slightly right of the nose of the aircraft and 14 nautical miles southwest of the destination airport.

The airplane was on an on-demand air-taxi flight operating under 14 CFR Part 135 and was destroyed when it impacted trees and terrain while circling to land during a non-precision instrument approach at night. The airplane came to rest 1.74 nautical miles and 226 degrees magnetic from the intended airport. A weather briefing was obtained and instrument meteorological conditions were present along the route of flight at the time of the briefing. Weather conditions for the two reporting stations closest to the destination were obtained by the airplane prior to executing the approach. The weather reports listed ceilings and visibilities as 400 to 500 feet overcast and 5 to 7 statute miles. The airport elevation is 669 feet and the minimum descent altitude for the approach was listed as 1,240 feet. There was no weather reporting station at the destination airport at the time of the accident. According to the operators General Operations Manual, the pilot was responsible for the dispatch of the airplane including flight planning, and confirming departure, en-route, arrival and terminal operations compliance. The manual also states, "For airports without weather reporting, the area forecast and reports from airports in the vicinity must indicate that the weather conditions will be VFR [visual flight rules] at the ETA so as to allow the aircraft to terminate the IFR operations and land under VFR. (Note: a visual approach is not approved without weather reporting)." For 14 CFR Part 135 instrument flight operations conducted at an airport, federal regulations require weather observations at that airport. Furthermore, the regulations state that, for 14 CFR Part 135 operations, an instrument approach cannot be initiated unless approved weather information is available at the airport where the instrument approach is located, and the weather information indicates that the weather conditions are at or above the authorized minimums for the approach procedure. The commercial pilot held a type rating for the accident airplane. The right seat occupant was a commercial pilot employed by the operator and did not hold an appropriate type rating for the accident airplane. The pitch trim selector switch was found set to the co-pilot side. The regulations state that 14 CFR Part 135 operators cannot use the services of any person as an airman unless that person is appropriately qualified for the operation for which the person is to be used. The circling approach was made over primarily unlit land and water. An FAA publication states that during night operations, "Distance may be deceptive at night due to limited lighting conditions. A lack of intervening Page 2 of 17 CHI01FA083 references on the ground and the inability of the pilot to compare the size and location of different ground objects cause this. This also applies to the estimation of altitude and speed. Consequently, more dependence must be placed on flight instruments, particularly the altimeter and the airspeed indicator." No anomalies were found with respect to the airframe, engines, or systems that could be associated with a pre-impact condition.