NTSB Identification: CHI06FA077A
14 CFR Part 91: General Aviation
Accident occurred Sunday, February 05, 2006 in Watertown, WI
Aircraft: Short Brothers SD-360-300, registration: N3735W
Injuries: 3 Fatal, 1 Minor, 2 Uninjured.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed.

On February 5, 2006, at 1653 central standard time, two Shorts Brothers SD-360-300 airplanes (N3735W, N372AC), collided at approximately 2,500 feet mean sea level (msl) near Watertown, Wisconsin. Both aircraft were operated by Air Cargo Carriers, Inc., based in Milwaukee, Wisconsin. N3735W was destroyed during impact with the ground and subsequent ground fire. N372AC was substantially damaged during the midair collision and subsequent emergency landing at Dodge County Airport (UNU), Juneau, Wisconsin. Visual meteorological conditions prevailed at the time of the accident. Both airplanes were operating under the provisions of 14 Code of Federal Regulations Part 91 without flight plans. The pilot, co-pilot, and passenger aboard N3735W were fatally injured. The pilot and co-pilot of N372AC were not injured. The passenger aboard N372AC reported minor injuries. N3735W and N372AC departed General Mitchell International Airport (MKE) at 1555 and 1615, respectively, for local area flights.

According to interviews with the flight crew of N372AC, the flights were performed to verify the fuel flow rates for some auxiliary fuel tanks that had been recently installed on both airplanes. Prior to departure, both flight crews decided that they would join-up after departure in order to take video and still photography of each airplane. After departure and clearing MKE airspace, the flight crew of N372AC established radio and visual contact with N3735W. N3735W then proceeded to perform several fly-bys past N372AC who remained on constant headings and altitude. The flight crew reported that N3735W then came up along their left side and flew in formation with approximately 100-150 feet lateral separation. The pilot-in-command (PIC) of N372AC reported that a pilot of N3735W then announced over the radio that they would turn right and descend below N372AC. The PIC stated that N3735W's left wing impacted the left wing and engine of his airplane. The PIC reported that he had attempted to climb in an attempt to avoid impacting N3735W. After the collision, N372AC rolled to the left and pitched down significantly before the flight crew regained control of the airplane. The flight crew declared an emergency with Madison Approach Control and diverted to UNU for an emergency landing. The flight crew reported that N372AC experienced a complete hydraulic failure and was losing hydraulic fluid. The flight crew performed an emergency landing on runway 08 (5,069 feet by 100 feet, asphalt) with flaps retracted and a partially extended landing gear. The airplane overran the end of the runway, coming to rest about 100 feet from the departure threshold.

N3735W impacted terrain and was consumed during a subsequent ground fire. The outboard 3/4 of the left wing was found about 0.42 nm from the main wreckage and was not fire damaged. The left aileron was found on runway 08 at UNU where N372AC had landed.

FMI: www.ntsb.gov/ntsb/brief.asp?ev_id=20060209X00189&key=3