ERA09FA389

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.

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.

HISTORY OF FLIGHT On July 8, 2009, at 1452 eastern daylight time, a Cessna 421C, N4467D, was destroyed after it impacted the waters of the Gulf of Mexico, about 25 nautical miles northwest of Port Richey, Florida. The instrument-rated commercial pilot and 4 passengers were fatally injured. Instrument meteorological conditions prevailed in the area of the accident and an instrument flight rules (IFR) flight plan had been filed for the flight, which departed Collin County Regional Airport (TKI), McKinney, Texas destined for Tampa International Airport (TPA), Tampa Florida. The corporate flight was conducted under 14 Code of Federal Regulations Part 91. According to voice data provided by the Federal Aviation Administration (FAA), The pilot of indicated that he had reviewed the weather conditions when he called the Houston Automated Flight Service Station to file his IFR flight plan prior to departure. At that time the pilot indicated he was aware of the thunderstorm activity over the Gulf of Mexico and Florida, and that he was anticipating deviating around the weather as necessary. According to radar and voice data provided by the FAA, just prior to the accident, the pilot had been in communication with the Jacksonville Air Route Traffic Control Center (ARTCC). During the flight the pilot requested and had been provided both weather information along his route of flight and "ride reports" from other aircraft. At 1446:34, the pilot reported to ARTCC that he was encountering turbulence and requested directions to get out of the turbulence. The pilot was then advised by the controller that if he continued straight ahead for about two minutes, he should be clear of the weather. At 1446:56 the pilot advised ARTCC that he was experiencing a two thousand foot per minute descent rate. At 1447:02 the controller then asked him if he would like to turn around and go back in the opposite direction, to which the pilot responded that he would. At 1847:07, the pilot was cleared to reverse course. Sixteen seconds later, the pilot declared an emergency, and advised that the airplane was "upside down". There were no further transmissions from the pilot, and radar contact was lost with the airplane when it descended below the radar coverage area. PERSONNEL INFORMATION According to FAA records, the pilot held a commercial pilot certificate with airplane single engine land, airplane multi-engine land, and instrument airplane ratings. His most recent FAA second-class medical certificate was issued on April 23, 2009. He reported 1,940 total hours of flight experience on that date. AIRCRAFT INFORMATION According to FAA and maintenance records, the airplane was manufactured in 1979. It was a two engine, pressurized, 7 seat airplane of conventional construction. It was approved for day and night IFR operations and was equipped with weather radar, a Stormscope weather mapping sensor, and an XM satellite receiver which enabled the pilot to receive the XM weather data stream. It had been modified from its original configuration by RAM Aircraft LP and was equipped with winglets, spoilers, and vortex generators. It was powered by two Continental GTSIO-520-L engines, each producing 375 horsepower. It could cruise at 228 knots, had a range of 1,487 nautical miles, and could operate at altitudes up to 30,000 feet msl. The airplane's most recent annual inspection was completed on August 18, 2008. The last maintenance action was performed on the airplane on July 6, 2009. At the time of the last maintenance action, the airplane had accrued 4,325.6 total hours of operation. METEOROLOGICAL INFORMATION According to the National Weather Service at the time of the accident, an area of IFR conditions existed over southern Georgia into northern Florida generally north of the accident airplane's route of flight. Associated with these conditions was a large area of reduced visibility in moderate to heavy rain. Surrounding that area was an area of marginal visual flight rules (MVFR) conditions over portions of Georgia and northern Florida, and two other areas across central Florida over the eastern and western portions of the state associated with thunderstorms and rain showers. The National Center for Atmospheric Research (NCAR) Regional Radar Mosaic Chart which was valid for the time of the accident also depicted a band of "intense to extreme" intensity echoes which extended across the Alabama and Florida panhandle into southern Georgia, and was associated with strong to potentially severe thunderstorms. A second east-to-west band of echoes associated with thunderstorms and rain showers also extended from the east to west coast of central Florida into the Gulf of Mexico. This band was characterized as a broken area of strong to intense cells along the southern portion with an extensive area of stratiform precipitation of light to moderate intensity echoes extending northward. The reported weather at Hernando County Airport (BKV), Brooksville, Florida approximately 47 miles east-north-east of the debris fields, at 1453, one minute after the accident, included: wind, 340 at 9 knots, visibility 1and 3/4 miles in light thunderstorms and rain showers mist, few clouds at 200 feet, broken clouds at 2,600 feet, overcast at 3,400 temperature 24 degrees C, dew point 23 degrees C, altimeter setting of 29.98 inches of mercury, and lightning in the distance, all quadrants. Four minutes later, the reported weather at BKV, included: wind calm, visibility 1/2 mile in heavy thunderstorms and rain showers, fog, few clouds at 200 feet, scattered clouds at 1,000 feet, overcast at 2,400 feet, temperature 24 degrees C, dewpoint 23 degrees C, altimeter setting of 29.98 inches of mercury, and lightning in the distance, all quadrants WRECKAGE AND IMPACT INFORMATION Search and rescue operations were undertaken by the United States Coast Guard (USCG), St. Petersburg Sector, utilizing surface vessels and aircraft. A 2-mile-long by 100-yard-wide debris field was located on the surface of the water at approximately 2000 on the day of the accident. On July 9, 2009, a second larger debris field was also discovered floating on the surface of the water approximately 4 miles northeast of the first debris field. At 1555, The Safety Board was advised by the USCG that no survivors had been found and that search and rescue operations had been suspended. Follow on searches by a contractor utilizing side scan sonar were conducted and multiple targets were detected. The search was suspended however, before the targets could be examined by divers, and the wreckage was never recovered. TESTS AND RESEARCH The debris fields were located near one of the stronger cells on the southern side of the band of echoes which had been depicted on the NCAR Regional Radar Mosaic Chart. At the time of the accident, The National Oceanic and Atmospheric Administration (NOAA) operated 159 high-resolution Doppler weather radar sites as part of the next generation radar network (NEXRAD). According to NOAA, these NEXRAD sites were equipped with Weather Surveillance Radar-1988, Doppler (WSR-88D) weather surveillance radar units which emit pulses of energy into the atmosphere at regular intervals. When this energy encounters something (a raindrop, a snowflake, a mountain, etc.), some of the energy is scattered back to the radar dish. The amount of energy, which was received at the radar dish, was measured in units (decibels) of Z (dBZ). It is a meteorological measure of equivalent reflectivity (Z) of a radar signal reflected off a remote object. The higher the dBZ value the larger the object i.e. large raindrops and hail produce high dBZ values. In general, dBZ values greater than 15 indicate areas where precipitation is reaching the ground. On the other hand, dBZ values less than 15 usually are an indication of very light precipitation which in most cases is evaporating in