Flight Design GMBH CTLS accident near Racine, Wisconsin, May 18, 2021
On May 18, 2021 at about 1:00 am local time, a 2008 Flight Design GMBH CTLS, registered N521CT, was destroyed in an accident during approach near Racine, Wisconsin (Batten Intl airport). It was an instructional flight under general aviation rules (Part 91). 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The fatigue failure of the carburetor throttle control cable, which resulted in a partial loss of engine control.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 18, 2021 · about 1:00 am local time
- Place
- Racine, Wisconsin · Batten Intl · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Flight Design GMBH CTLS, built 2008 · all CTLSs on the register
- Registration
- N521CT · no longer on the register · serial F-08-09-03
- Damage
- Destroyed
- Flight
- Instructional flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
During a solo cross-country flight, the student pilot returned to the departure airport after the engine began to vibrate when power was reduced. She attempted three landings that were aborted due to excessive airspeed. During the fourth landing attempt, the airplane touched down fast and bounced several times on the runway. The student pilot aborted the landing and added full engine power to climb, but the airspeed decreased. The airplane collided with a tree and a building and was destroyed by impact forces. Postaccident examination of the airplane revealed that one of the two throttle control cables had separated from its carburetor at the control arm. The cable separation from the carburetor resulted in the carburetor’s spring-loaded throttle control moving to full throttle while the second carburetor would have been at a position selected by the cockpit throttle control. When the pilot reduced the cockpit throttle control for landing, the carburetor with the broken cable would have continued operating at maximum throttle regardless of the cockpit throttle control position, which likely resulted in the engine vibration and the excessive airspeed for landing. Metallurgical examination of the separated control cable revealed that a tightly focused clamping force on the carburetor cable attachment bolt resulted in fatigue failure of the cable.
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 from the NTSB's investigation tables, in plain English
What happened, in order
- Landing area overshoot during landing
- Powerplant sys/comp malf/fail during approach defining event
- Collision with terrain or object (not controlled flight into terrain) during landing
The NTSB's findings
- Aircraft › Aircraft power plant › Engine fuel and control › Fuel control/carburetor › Failure
Pilot
- Certificate: student
- Flight time: 83 in this make and model
- Last flight review: May 17, 2021
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: left
- Injury: minor injuries
The aircraft
- Seats: 2
- Landing gear: fixed
- Engine: Rotax 912ULS (piston); 0 hours total
The flight
- Departed from: BUU Burlington WI at 7:39 pm
- Flight plan: VFR
- Runway 14/3, 4,422 ft by 100 ft
Weather at the time
- Light: daylight
- Wind: from 100° at 3 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 59°F (15°C), dew point 52°F (11°C)
- Altimeter: 30.21 inHg
- Observation at 7:53 pm from KRAC, 1 miles away
Weather report (METAR): KRAC 180053Z AUTO 10003KT 10SM CLR 15/11 A3021 RMK AO2 SLP229 T01500111
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 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.
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number CEN21LA222.