Friday, September 17, 2021

NTSB releases preliminary report on Argyle plane crash

plane_crash2-5-15The National Transportation Safety Board has released a preliminary report on the plane crash in Argyle that killed pilot William Blake Graves, a Flower Mound resident.

His twin-engine Cessna 441 twin turbo prop airplane was on approach to Denton Enterprise Airport on Feb. 4 when the crash occurred shortly after 9 p.m. in a grassy area of a construction site in the 1400 block of Stonecrest Road.

The plane, registered to Del Air Enterprises II, LLC, left Willmar Municipal Airport in Willmar, Minn., at 6:29 p.m. According to the report, the plane was about 35 miles northwest of Denton Enterprise Airport when a southbound course was established with the air traffic controller. Graves was flying on an instrument flight rules plan, not a  visual flight plan.

The report indicates ongoing conversation between the pilot and the airport control tower regarding final approach. An air traffic controller told Graves that another plane’s pilot reported light-to-moderate turbulence with visibility limited to 1.5 miles.

At 9:03, the Denton airport’s automated surface observing system reported 2-mile surface visibility with light rain, mist and winds at just over 19 mph, gusting to 28.7 mph.

The information was relayed to Graves, who was told to descend to 2,500 feet mean sea level. Graves also was told to turn to a south heading and later to an east heading but, according to radar data, he did not make the eastern turn.

The plane continued to descend heading south. The report indicates that while the pilot acknowledged most requests, he did not change course.

At 9:08 p.m., an automated low altitude alert sounded, indicating the plane had descended to 1,500 mean sea level. Though Graves indicated he was “going back up,” the plane continued to descend. The air traffic controller tried to contact the pilot again but heard no response, according to the report.

According to preliminary airplane performance calculations, based on available radar data, during the time period 9:06:43 p.m. to 9:08:43 p.m., the airplane’s ground speed decreased from about 145 knots to 95 knots and the airplane descended from 2,400 feet mean sea level to 1,500 feet mean sea level. During the final 28 seconds of radar data, the airplane’s ground speed further decreased from 95 knots to 55 knots, while the descent rate decreased from 1,300 feet per minute to 650 feet per minute.

The plane’s flight path was captured by a security video camera installed on a building about a half mile southeast of the accident site, according to the report.

The video camera captured the accident airplane’s wingtip navigation and strobe lights as it crossed from left to right.

According to a preliminary review of the camera footage, the airplane entered the camera’s field of view at 9:08:48 p.m. and appeared to be in a wings level descent as it continued across the first half of the camera’s lateral field of view. At 9:09 p.m., the descent angle increased substantially before the airplane entered a near-vertical spiraling descent. The airplane’s navigational lights and strobes were not visible after 9:09:09 p.m.

In 911-emergency calls received following the accident, several individuals reported hearing an airplane overfly their position at a low altitude followed by the sound of a large ground impact.

First responders with the Argyle Fire Department, upon arrival at the accident site, told investigators there was no evidence of ice or frost accumulation on the airplane’s fuselage, wings, or tail. Additionally, the first responders reported that there was a substantial smell of fuel at the accident site. There was no evidence of an explosion or postimpact fire. The pilot was seated in the left cockpit seat, secured by a lap belt.

Investigators reported no wreckage debris path at the accident site. The entire lower fuselage surface was crushed upward, consistent with a vertical impact. The airplane tail section was found partially separated, according to the report.

The landing gear was extended as were wing flaps at a 10-degree angle.

The wing flaps were found extended about 10-degrees. Two approximately 12-inch deep holes were observed aside and slightly behind the engines where the rotating propellers had dug into the soil. Both propellers exhibited significant bending of their blades opposite the direction of rotation.

Investigators indicated in the report that evaluations of flight instruments, other parts of the plane and mobile devices found inside the cabin were ongoing.

Graves, 52, was a pilot for 28 years and enjoyed flying as a hobby.He was licensed as a commercial pilot.

Graves embarked on his career with Domino’s Pizza as a driver in the 1980’s, opening his first store in Willmar in 1985. He continued growing his presence at Dominos throughout his life, with the opening of his 100th store on Nov. 15, 2014.  This year marked his 30th as a Domino’s

Graves was married to Susan “Sue” Strodtman on July 2, 1994. Together, the couple had six children.


CTG Staff
The Cross Timbers Gazette News Department

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