National Transportation Safety Board public affairs officer Terry Williams said the agency’s investigation is ongoing and no new details are available.
Williams said NTSB’s investigations can take up to a year, but reports with new information can be made public periodically.
The Beechcraft 390 Premier 1 carrying five members of The Vein Guys clinic staff crashed after aborting a landing on the runway about 8 p.m. Feb. 20. The plane went airborne at the end of the runway and hit the top of a 60-foot tall concrete utility pole.
NTSB member Robert Sumwalt said the plane’s left wing was sheared off, leaking fuel and causing the aircraft to catch fire. The plane continued for another quarter-mile and went through trees before crashing in a wooded area.
Vein Guys co-founder Steven Roth was killed, along with employees Tiffany Porter, Lisa Volpitto, Kim Davidson and Heidi McCorkle. The crew was traveling from a vascular surgery practice in Nashville, Tenn., to Thomson, investigators said.
Pilots Richard Trammell and Jeremy Hayden were injured.
Investigators spent almost a week collecting evidence from the wreckage site to determine probable cause for the crash and how two survived while others perished. Sumwalt said the plane was almost destroyed by fire, and wreckage was strewn across about 100 yards.
Federal safety officials said there were no distress calls between the pilot and air traffic controllers.
Grainy footage from an airport security camera captured some of the aborted landing and was sent to a lab in Washington for analysis.