Argyle, FL, USA
N6569L
Mitsubishi MU-2B-35
Prior to the accident flight, the pilot obtained a preflight weather briefing and filed an instrument flight rules flight plan. The briefer noted no adverse weather conditions along the route. The airplane departed the airport at 0853, and climbed to FL190. The first two hours of the flight was uneventful, and the aircraft was handed off to Jacksonville Air Route Traffic Control Center (ZJX ARTCC) at 1053. The pilot contacted ZJX Crestview sector at 1054:45 with the airplane level at FL190. At 1102, the Crestview controller broadcasted an alert for Significant Meteorological Information (SIGMET) 32E, which pertained to thunderstorms in portions of Florida southwest of the pilot's route. At 1103, the controller cleared to the airplane to descend to 11,000 feet and the pilot again acknowledged. At 1110:21, the pilot was instructed to contact Tyndall Approach. The pilot checked in with the Tyndall RAPCON North Approach controller at 1110:39. The pilot was told to expect a visual approach. Shortly thereafter, the pilot transmitted, "...we're at 11,000, like to get down lower so we can get underneath this stuff." The controller told the pilot to stand by and expect lower [altitude] in 3 miles. About 15 seconds later, the controller cleared to pilot to descend to 6,000 feet, and the pilot acknowledged. At 1112:27, the pilot was instructed to contact Tyndall Approach on another frequency. The airplane's position at that time was just northwest of REBBA intersection. The Panama sector controller cleared the pilot to descend to 3,000 feet at his discretion, and the pilot acknowledged. There was no further contact with the airplane. The controller attempted to advise the pilot that radar contact was lost, but repeated attempts to establish communications and locate the airplane were unsuccessful. A witness, located approximately 1 mile south of the accident site, reported he heard a "loud bang," looked up and observed the airplane in a nose down spiral. The witness reported there were parts separating from the airplane during the descent. The witness stated it was raining and there was lightning and thunder in the area. Local authorities reported that the weather "was raining real good with lightning and the thunderstorm materialized very quickly." The main wreckage came to rest near the edge of a swamp in tree covered and high grassy terrain. The left wing, left engine, and the left wing tip tank were located in a wooded area approximately 0.6 miles northwest of the main wreckage. The left wing separated from the airplane inboard of the left engine and nacelle. Examination of the fracture surfaces indicated that both the front and rear spars failed from "catastrophic static up-bending overstress..." The airplane flew through an intense to extreme weather radar echo containing a thunderstorm. Although the controllers denied that there was any weather displayed ahead of the airplane, recorded radar and display data indicated that moderate to extreme precipitation was depicted on and near the route of flight. During the flight, the pilot was given no real-time information on the weather ahead. The airplane was equipped with a weather radar system and the system provided continuous en route weather information relative to cloud formation, rainfall rate, thunderstorms, icing conditions, and storm detection up to a distance of 240 miles. No anomalies were noted with the airframe and engines.
HISTORY OF FLIGHT On September 1, 2006, approximately 1115 central daylight time, a Mitsubishi MU-2B-35 twin-engine turboprop airplane, N6569L, was destroyed when it impacted terrain near Argyle, Florida. The airline transport pilot, who was the sole occupant, was fatally injured. The airplane was registered to Intercontinental Jet Incorporated, Tulsa, Oklahoma, and operated by Berg Steel Pipe Corporation, Panama City, Florida. Day instrument meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan was filed for the Title 14 Code of Federal Regulations Part 91 positioning flight. The flight departed Tulsa International Airport (TUL), Tulsa, Oklahoma, approximately 0853, and was en route to Panama City Bay County International Airport (PFN), Panama City, Florida. According to transcripts provided by Lockheed Martin, the pilot contacted the McAllister, Oklahoma, Federal Contract Facility at 0726 to file an IFR flight plan and obtain a preflight weather briefing for the flight from TUL to PFN. The briefer noted no adverse weather conditions along the route, stating that the pilot could expect to encounter only some showers between Tulsa and Fort Smith, Arkansas, and no other significant weather. The pilot then filed a flight plan from TUL direct to DEFUN intersection (near DeFuniak Springs, Florida), then direct to PFN, requesting flight level (FL) 190. The briefer accepted the flight plan, asked the pilot if he had any further questions, then terminated the call. The airplane departed TUL at 0853 and climbed to FL190. The flight was uneventful, and the aircraft was handed off to Jacksonville Air Route Traffic Control Center (ZJX ARTCC) at 1053. The pilot contacted ZJX Crestview sector at 1054:45 with the airplane level at FL190. At 1100, the radar controller instructed the pilot to descend to 15,000 feet mean sea level (msl) and provided the Crestview altimeter setting. The pilot acknowledged. At 1102, the Crestview controller broadcasted an alert for Significant Meteorological Information (SIGMET) 32E, which pertained to thunderstorms in portions of Florida, southwest of the pilot's route. At 1103, the controller cleared the pilot to descend to 11,000 feet, and the pilot again acknowledged. At 1110:21, the pilot was instructed to contact Tyndall Approach on frequency 125.2 MHz. Review of the interphone communications between the Tyndall Radar Approach Control (RAPCON) North Approach radar assistant and a controller at Eglin Air Force Base (AFB) showed that at 1110:18, the Tyndall radar assistant asked Eglin for information on the intensity of radar-depicted weather in the area of DEFUN intersection (Eglin AFB was responsible for airspace north and west of the Tyndall area, and their system provided good coverage of the accident airplane's track and radar-observed precipitation in the area of the accident). The Eglin controller responded that his display was showing intensities one through six. The Tyndall radar assistant replied, "One through six?...Nothing specific? Okay, thanks," and concluded the call. The pilot checked in with the Tyndall RAPCON North Approach controller at 1110:39. The pilot reported having automatic terminal information service (ATIS) information Tango. The Tyndall controller advised that Uniform ATIS was current and provided the pilot with the updated information. PFN was reporting estimated wind from 250 degrees at 5 knots, visibility 10 miles, and few clouds at 3,000 feet. The pilot was told to expect a visual approach. He acknowledged the new weather, and then transmitted, "...we're at 11,000, like to get down lower so we can get underneath this stuff." The controller told the pilot to stand by and expect lower [altitude] in 3 miles. About 15 seconds later, the controller cleared to pilot to descend to 6,000 feet, and the pilot acknowledged. At 1112:27, the pilot was instructed to contact Tyndall Approach on 119.1 MHz (the Panama sector), and he did so at 1112:42. Recorded keyboard entries obtained from ZJX Data Analysis and Reduction Tool (DART) data reduction showed that the Crestview radar controller dropped the data block for the airplane from her display at 1112:34 as the airplane descended through 10,000 feet. The airplane's position at that time was just northwest of REBBA (accident site located 1.1 nautical miles southeast) intersection. The Panama controller cleared the pilot to descend to 3,000 feet at his discretion, and the pilot acknowledged. There was no further contact with the airplane. At 1115:40, the Panama controller attempted to advise the pilot that radar contact was lost, but repeated attempts to establish communications and locate the airplane were unsuccessful. A witness, located approximately 1 mile south of the accident site, reported he heard a "loud bang," looked up and observed the airplane in a nose down spiral toward the terrain. The witness reported there were parts separating from the airplane during the nose-down descent. At the time of accident, the witness stated it was raining and there was lightning and thunder in the area. Local authorities, who responded to the accident site, reported that the weather "was raining real good with lightning and the thunderstorm materialized very quickly." PERSONNEL INFORMATION The pilot, who was seated in the left front seat position, held an airline transport pilot certificate, issued May 9, 1975, with an airplane multi-engine land rating, and a commercial pilot certificate with an airplane single-engine land rating. The pilot held type ratings in BE400, DC-B26, DC-3, FA-C123, MU300, G-TBM, L-18, and N-B25 aircraft. The pilot was issued a second-class medical certificate on August 29, 2006, with a limitation for corrective lenses. According to the Federal Aviation Administration's (FAA) airman records, the pilot reported on March 28, 2006, he had accumulated 30,780 total flight hours and 18,650 total flight hours in turboprop airplanes. The pilot's logbooks were not located. According to the pilot's records, on February 28, 2006, at SimCom International Flight Academy, the pilot satisfactorily completed Wings Program Phase IV training requirements outlined in the FAA's Advisory Circular 61-91H. According to the pilot's son, the pilot had approximately 10,000 flight hours in the Mitsubishi MU-2 model airplanes, and 50 to 100 flight hours in the accident airplane. In addition, the son stated the pilot was a former sales representative and pilot for Mitsubishi. AIRCRAFT INFORMATION The accident airplane, a long-body Mitsubishi MU-2B-35, serial number 645, was a high performance, high wing, semi-monocoque design airplane. The airplane was powered by two 665-horsepower Honeywell TPE331-6-252M turboprop engines (serial numbers P-20126C and P-20122C). The airplane was equipped with 3-bladed, Hartzell HC-B3TN-5E single acting, hydraulically operated, constant speed with feathering and reversing capability, propellers. Flight controls for the left and right seats were installed in the airplane. The airplane was equipped with a Bendix/King RDR-1200 weather radar system and an IN-1102A radar indicator. The RDR-1200 system provided continuous en route weather information relative to cloud formation, rainfall rate, thunderstorms, icing conditions, and storm detection up to a distance of 240 miles. The IN-1102A indicator contained front panel selections of power, range, tilt adjustment of antenna, receiver gain control, hold, self-test, and stab adjust. The airplane was issued a standard airworthiness certificate on May 6, 1974. The airplane was registered to the owner on September 13, 2004, and was maintained under a manufacturer's inspection program. According to the registered owner, the airplane was on lease to Berg Steel Piper Corporation for a period of months while the operator's airplane underwent maintenance. The accident flight was the first flight of the lease agreement. In addition, the accident airplane was utilized for flight training in the FAA's Flight Standardization Board (FSB) review in 2005. According to the maintenance records obtained from the registered owner, prior to the accident flight, the airframe had a total time of 6,641.6 hours (Hobbs 2,420.0). The left engine, serial number (S/N) P-20126C, had accumulated 6,530.6 hours and 8,004 cycles since new; 3,808.6 hours and 3,921 cycles since overhaul; and 790.6 hours since hot section overhaul. The right engine, S/N P-20122C, had accumulated 6,565.8 hours and 7,992 cycles since new; 3,843.8 hours and 3,909 cycles since overhaul; and 839.8 hours since hot section overhaul. At the request of the NTSB investigator-in-charge (IIC), the airframe manufacturer calculated the airplane's weight and balance at takeoff and at the time of the accident. According to the registered owner, the airplane's fuel tanks were topped off prior to departure. The estimated weight of baggage in the rear of the airplane was 100 pounds (lbs). The airplane's takeoff weight and center of gravity were calculated to be 10,378.20 lbs and 197.54 inches, respectively. The airplane's weight and center of gravity at the time of the accident were calculated to be 8,626.20 lbs and 197.66 inches, respectively. The airplane's maximum takeoff weight was 10,775 lbs and the center of gravity limits were 190.9 to 199.4 inches. METEOROLOGICAL INFORMATION At 1012, the Bob Sikes Airport (CEW), Crestview, Florida, automated surface observing system (ASOS), located approximately 25 miles northwest of the accident site, special observation reported the wind from 260 degrees at 4 knots, visibility 10 statute miles, scattered clouds at 5,500 feet, overcast ceiling at 7,500 feet, temperature 23 degrees Celsius, dew point 19 degrees Celsius, and altimeter setting of 29.92 inches of Mercury. Remarks included distant lightning in the south, thunderstorm ended at 1006, and rain ended at 0955. At 1053, the CEW ASOS reported the wind calm, visibility 10 statute miles, broken cloud ceiling at 6,500 feet, overcast at 9,000 feet, temperature 23 degrees Celsius, dew point 20 degrees Celsius, and altimeter setting of 29.92 inches of Mercury. Remarks included distant lightning in the southeast. Level III Doppler Weather Radar data from the Fort Rucker, Alabama (EOX), WSR-88D were reviewed using McIDAS (Man-computer Data Access System). For the 1112 to 1117 scans, the EOX Composite Reflectivity Image indicated that the weather echo intensities (VIP Level 5) occurred along the route of flight and near the accident site. Level II Doppler Weather Radar data from the Tallahassee, Florida (TLH), WSR-88D were reviewed using IDV (Integrated Data Viewer). For the 1108:54 scan, the TLH Base Reflectivity Image indicated extreme (VIP Level 6) weather radar echoes in the accident area at the time of the last air traffic control (ATC) radar contact. For the 1114:38 scan, the TLH Base Reflectivity Image indicated intense (VIP Level 5) weather radar echoes in the accident area at the time of the last ATC radar contact. There were no SIGMETSs, Airmen's Meteorological Advisories (AIRMETs), Convective SIGMETs, or ZJX Weather Advisories in effect for the time and location of the accident. The following information was from a written statement of the meteorologist on duty at the time of the accident at the Aviation Weather Center in Kansas City, Missouri. A Convective SIGMET for the Florida (FL) panhandle and southeastern Alabama (AL) was not issued at 1055 because "WST criteria as described in NWS Directive 10-811 (6.41) had not been met." In addition, the meteorologist stated that "I did not issue a Convective SIGMET Special during the next half hour for the FL panhandle and southeastern AL, because the convection remained isolated and did not meet Convective SIGMET Special criteria described in NWS Directive 10-811 (6.42). According to an email from ZJX Weather Service Unit meteorologist on duty at the time of the accident, a Center Weather Advisory (CWA) for the activity in the area of the accident was not issued because the criteria for issuance of CWAs was not met. The meteorologist noted that the criteria is contained in NWS Directive 10-803. The meteorologist also noted that during the two hours before the accident, radar showed isolated rain shower activity in the area with no lightning indicated on the Weather and Radar Processor (WARP) display. According to the meteorologist the activity remained isolated and was not impacting ARTCC operations, therefore a CWA was not required. In addition, the meteorologist noted that because of the replacement of a defective WARP display monitor, he had no WARP meteorological data during the time of monitor replacement which coincided with the time of the accident. The WARP workstation was down from about 1100 to 1115. According to the meteorologist, "while WARP workstation was down, the availability of weather data for support to the ARTCC was degraded and display weather data when WARP is unavailable." However, the meteorologist noted that they do have access to weather radar data through NWS internet sites. RADAR AND COMMUNICATIONS Tyndall RAPCON is a United States Air Force (USAF) approach facility, and is equipped with a TPX-42 radar system that does not record aircraft target or weather information. Radar data for this accident was obtained from the Tyndall AFB ARSR-4 long range radar site. This radar site is not used by Tyndall RAPCON for air traffic control purposes, but is used by both ZJX and USAF air defense controllers for surveillance. According to recorded Display System Replacement (DSR) WARP NEXRAD display data, an area of moderate, severe, and extreme level weather was along the airplane's route, and was displayed on ZJX and Eglin AFB radar displays in digital form with intensity information available to controllers at both facilities. Tyndall AFB controllers showed the weather area; however, had no direct indication of precipitation intensity. An ATC group was formed and conducted several interviews with air traffic personnel and controllers. The following are summaries of the interviews that the ATC group completed. For complete interview summaries, refer to the NTSB ATC Group Chairman's Factual Report. Crestview Radar Controller On the day of the accident, the controller was working a 0900 to 1700 shift, and the accident occurred on her first day back to work after three days off. The controller became aware of the airplane when the pilot checked on frequency northwest of CEW. At that time, the airplane was on top of the Pensacola North military operations area (MOA). After the airplane passed the MOA boundary, she cleared the pilot to descend to 15,000 feet and the pilot acknowledged. Shortly afterward, she cleared the airplane to descend to 11,000 feet and started a handoff to Tyndall RAPCON. RAPCON accepted the handoff and she instructed the pilot to contact Tyndall. The controller had no further contact with the pilot. The controller stated that there was some weather in the Eglin AFB restricted area and some scattered weather in the area northwest of Tyndall AFB, about 20 miles southeast of DEFUN. At some point while handling the airplane, the controller requested a route display to see where the flight was going, but did not see any weather along the airplane's route. After transferring the airplane to RAPCON, the controller continued working other aircraft. Approximately 12 minutes later, the RAPCON controller called back to ask about the accident airplane asking if she had seen or heard from the airplane. She replied that she had not and would start lost aircraft procedures. She again looked at the weather in the area, but observed nothing new. When asked to describe her understanding of the NEXRAD system, she stated it displayed moderate, heavy, and extreme levels of weather and described the appearance of each on the display. There are 8 NEXRAD radars which provide information to ZJX. When asked whether any were out of service at the time, she stated that there were two radars out of service, but she did not know about that until after the accident. Controllers are not routinely i
the pilot's inadvertent flight into thunderstorm activity that resulted in the loss of control, design limits of the airplane being exceeded and subsequent in-flight breakup. A contributing factor was the failure of air traffic control to use available radar information to warn the pilot he was about to encounter moderate, heavy, and extreme precipitation along his route of flight,
Source: NTSB Aviation Accident Database
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