Cessna 421C accident near Gulf Of Mexico, July 8, 2009
On July 8, 2009 at about 6:52 pm local time, a Cessna 421C, registered N4467D, was destroyed in an accident during enroute (cruise) near Gulf Of Mexico. It was an executive or corporate flight under general aviation rules (Part 91). 5 people were killed. The weather was instrument conditions (cloud, fog or low visibility).
The NTSB's probable cause their words, unchanged
The pilot’s decision to operate into a known area of adverse weather, which resulted in the inadvertent penetration of a severe thunderstorm, a subsequent loss of control, and in-flight breakup of the airplane.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 8, 2009 · about 6:52 pm local time
- Place
- Gulf Of Mexico · map
- Type
- Accident
- Injuries
- 5 people were killed.
- Weather
- instrument conditions (cloud, fog or low visibility)
- Aircraft
- Cessna 421C · all 421Cs on the register
- Registration
- N4467D · no longer on the register · serial 421C0634
- Damage
- Destroyed
- Flight
- Executive or corporate flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
Prior to the accident flight, the pilot indicated that he was aware of the thunderstorm activity along his route of flight and that he anticipated deviating around the weather as necessary. While enroute to his destination, the pilot requested and was provided both weather information and pilot reports from other aircraft by air traffic control (ATC). Upon encountering an area of thunderstorm activity that extended east-to-west across the route of flight, the pilot reported encountering significant turbulence, and then downdrafts of 2,000 feet per minute. He then requested a course reversal to exit the weather before he declared an emergency and advised ATC that the airplane was upside down. There were no further transmissions from the pilot and radar contact with the airplane was lost. Review of radar data revealed that the pilot had deviated south and then southwest when the airplane entered a strong and intense echo of extreme intensity. Visible imaging revealed that the echo was located in an area of a rapidly developing cumulonimbus cloud with a defined overshooting top, indicating the storm was in the mature stage or at its maximum intensity. Two debris fields were later discovered near the area where the cumulonimbus cloud had been observed. This was indicative that the airplane had penetrated the main core of the cumulonimbus cloud, which resulted in an inflight breakup of the airplane. Near the heavier echoes the airplane's airborne weather radar may have been unable to provide an accurate representation of the radar echoes along the aircraft's flight path; therefore the final penetration of the intense portion of the storm was likely unintentional.
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
- Windshear or thunderstorm during enroute (cruise)
- Turbulence encounter during enroute (cruise)
- Loss of control in flight during enroute (cruise) defining event
- Aircraft structural failure during enroute (cruise)
The NTSB's findings
- cause Environmental issues › Conditions/weather/phenomena › Convective weather › Thunderstorm › Decision related to condition
- cause Personnel issues › Action/decision › Action › Incorrect action selection › Pilot
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 1,940 hours in all
- Last flight review: August 4, 2008
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: left
- Injury: fatal
The aircraft
- Airframe total time: 4,326 hours
- Last inspection: annual inspection, August 18, 2008; 141 hours since
- Maximum gross weight: 7,610 lb
- Seats: 7
- Landing gear: retractable
- Engine 1: Continental GTSIO-520-L (piston); 0 hours total
- Engine 2: Continental GTSIO-520-L (piston); 0 hours total
- Operator: Q4 Aviation LLC
The flight
- Departed from: TKI Mckinney TX at 3:02 pm
- Destination: TPA Tampa FL
- Flight plan: IFR
Weather at the time
- Light: daylight
- Wind: from 010° at 7 knots, gusting 15
- Visibility: 8 statute miles
- Sky: overcast at 2,400 ft; a few clouds at 200 ft
- Temperature: 75°F (24°C), dew point 73°F (23°C)
- Altimeter: 29.97 inHg
- Observation at 6:57 pm from BKV, 47 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 4 |
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.