DEN06MA119

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 acci