Amateur-built SD-360-300 and amateur-built SD-360-300 mid-air collision near Watertown, Wisconsin, February 5, 2006
On February 5, 2006 at about 10:54 pm local time, 2 aircraft, amateur-built SD-360-300 (N3735W) and amateur-built SD-360-300 (N372AC), were involved in a mid-air collision near Watertown, Wisconsin. 3 people were killed and 1 person had minor injuries; 2 others were unhurt. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The flight crew failed to maintain clearance from another aircraft as they turned to break formation flight while maneuvering. Contributing to the accident was the decision of both flight crews to fly in formation.
The other airplane's flight crew failure to maintain clearance while maneuvering during formation flight. Contributing to the accident was the decision of both flight crews to fly in formation.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- February 5, 2006 · about 10:54 pm local time
- Place
- Watertown, Wisconsin · map
- Type
- Accident · mid-air collision
- Injuries
- 3 people were killed and 1 person had minor injuries; 2 others were unhurt.
- Weather
- visual conditions (good weather)
- Aircraft 1
- Amateur-built SD-360-300
- Registration
- N3735W · no longer on the register · serial SH-3735
- Damage
- Destroyed
- Flight
- Other work-use flight · general aviation rules (Part 91)
- Aircraft 2
- Amateur-built SD-360-300
- Registration
- N372AC · no longer on the register · serial SH-3720
- Damage
- Substantial damage
- Flight
- Other work-use flight · general aviation rules (Part 91)
The NTSB's narrative for the amateur-built SD-360-300 final · quoted from the NTSB record
Prior to departure, both flight crews decided that they would join-up while in flight to take video and still pictures of each airplane. Both aircraft were Shorts Brothers SD-360-300 turboprop airplanes. While flying in formation, N3735W announced over the radio that they would turn right, toward N372AC, and descend. During the turn, N3735W's left wing impacted the left wing and engine of N372AC. After the collision, N372AC rolled to the left and pitched down significantly before the flight crew regained control of the airplane. After the collision, N372AC was losing hydraulic fluid and eventually had a complete hydraulic system failure. The airplane made an emergency landing at a nearby airport with its flaps retracted and its landing gear partially extended. The airplane overran the end of the runway, coming to rest about 100 feet from the departure threshold. White paint transfer markings and scrapes were observed on the left wing deice boot, the outboard side of the left engine cowling was crushed inboard, the left wing-strut leading edge was torn open and bent, and the lower fuselage skin, immediately forward of the landing gear wheel wells and stub wing, was torn from left to right, consistent with a propeller strike. N3735W impacted terrain and the airplane was destroyed during a subsequent ground fire. The flight crew and passenger were killed. The outboard three-quarters of the left wing was separated from the main wreckage and was not fire damaged. The upper wing surface had linear scrapes diagonally across the wing skin. The left aileron from N3735W was found on the runway where N372AC had landed.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The NTSB's narrative for the amateur-built SD-360-300 final · quoted from the NTSB record
Prior to departure, both flight crews decided that they would join-up while in flight to take video and still pictures of each airplane. Both aircraft were Shorts Brothers SD-360-300 turboprop airplanes. While flying in formation, N3735W announced over the radio that they would turn right, toward N372AC, and descend. During the turn, N3735W's left wing impacted the left wing and engine of N372AC. After the collision, N372AC rolled to the left and pitched down significantly before the flight crew regained control of the airplane. After the collision, N372AC was losing hydraulic fluid and eventually had a complete hydraulic system failure. The airplane made an emergency landing at a nearby airport with its flaps retracted and its landing gear partially extended. The airplane overran the end of the runway, coming to rest about 100 feet from the departure threshold. White paint transfer markings and scrapes were observed on the left wing deice boot, the outboard side of the left engine cowling was crushed inboard, the left wing-strut leading edge was torn open and bent, and the lower fuselage skin, immediately forward of the landing gear wheel wells and stub wing, was torn from left to right, consistent with a propeller strike. N3735W impacted terrain and the airplane was destroyed during a subsequent ground fire. The flight crew and passenger were killed. The outboard three-quarters of the left wing was separated from the main wreckage and was not fire damaged. The upper wing surface had linear scrapes diagonally across the wing skin. The left aileron from N3735W was found on the runway where N372AC had landed.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record for the amateur-built SD-360-300 from the NTSB's investigation tables, in plain English
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; single-engine sea; instrument: airplane
- Flight time: 1,643 hours in all; 1,181 in this make and model; 59 in the last 90 days; 12 in the last 30 days
- Last flight review: September 1, 2005
- Medical certificate: Class 1 (without waivers/limitations)
- Seat: left
- Injury: fatal
Co-pilot
- Certificate: airline transport pilot, flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instrument: airplane
- Flight time: 7,015 hours in all; 4,984 in this make and model; 32 in the last 90 days; 10 in the last 30 days
- Last flight review: January 1, 2006
- Medical certificate: Class 1 (without waivers/limitations)
- Seat: rgt
- Injury: fatal
The aircraft
- Airframe total time: 10,077 hours
- Last inspection: approved inspection programme, January 1, 2006
- Maximum gross weight: 27,100 lb
- Seats: 6
- Landing gear: retractable
- Engine 1: Pratt & Whitney PT6A-67R (turboprop); 0 hours total
- Engine 2: Pratt & Whitney PT6A-67R (turboprop); 0 hours total
- Fire on the ground
The flight
- Departed from: MKE Milwaukee WI at 9:55 pm
- Flight plan: none
- A second pilot was aboard
Weather at the time
- Light: dusk
- Wind: from 310° at 7 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 28°F (-2°C), dew point 18°F (-8°C)
- Altimeter: 29.84 inHg
- Observation at 10:57 pm from RYV, 5 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 2 | |||
| Passengers | 1 |
The factual record for the amateur-built SD-360-300 from the NTSB's investigation tables, in plain English
Pilot
- Certificate: flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instrument: airplane
- Flight time: 1,524 hours in all; 630 in this make and model; 89 in the last 90 days; 13 in the last 30 days
- Last flight review: October 1, 2005
- Medical certificate: Class 1 (without waivers/limitations)
- Seat: left
- Injury: no injuries
Co-pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 519 hours in all; 122 in this make and model; 99 in the last 90 days; 14 in the last 30 days
- Last flight review: October 1, 2005
- Medical certificate: Class 1 (without waivers/limitations)
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 21,996 hours
- Last inspection: approved inspection programme, January 1, 2006
- Maximum gross weight: 27,100 lb
- Seats: 6
- Landing gear: retractable
- Engine 1: Pratt & Whitney PT6A-67R (turboprop); 0 hours total
- Engine 2: Pratt & Whitney PT6A-67R (turboprop); 0 hours total
The flight
- Departed from: MKE Milwaukee WI at 10:15 pm
- Flight plan: none
- A second pilot was aboard
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 2 | |||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.