The deadly crash of a Virginia State Police helicopter that had been flying near a white-nationalist rally in Charlottesville in 2017 was probably caused by “the pilot’s loss of helicopter control” as the aircraft headed swiftly toward the ground, federal investigators have found.

Also contributing to the crash, according to the National Transportation Safety Board, was pilot Lt. H. Jay Cullen’s “lack of recent and recurrent training” on how to recover from such a downward rush.

Investigators pointed to a Federal Aviation Administration handbook that says helicopter pilots should be trained to understand that such a dangerous condition, known as “settling with power,” can happen when a pilot tries to descend “at an excessively low airspeed in a downwind condition” or attempts to hover in circumstances beyond what “the helicopter’s performance allows.”

Investigators said they found anecdotal information that Cullen was aware of the risks of such an aerodynamic condition, also known in aviation parlance as “vortex ring state.”

However, “review of the accident pilot’s training records from 2001 to the accident found no record of him receiving settling with power or vortex ring state recognition and recovery training on the accident helicopter make and model,” the NTSB wrote in a report this week.

The training manual for the state police aviation unit did not list the dangerous condition, and how to avoid it, in its sample lesson plans, according to the NTSB.

The NTSB previously discussed the training issue in a report issued in May.

State police spokeswoman Corinne Geller declined to answer questions about whether the aviation unit is requiring such recurrent training now. “Due to the pending litigation related to the crash, state police is not able to comment,” Geller said.

Survivors of Cullen and his colleague, Trooper-Pilot Berke Bates, who was serving as an observer on the Aug. 12, 2017, flight, have filed wrongful-death suits against the state and manufacturers of the helicopter and its components, among them Bell.

Philadelphia aviation lawyer Arthur Alan Wolk, who represents the families, said Cullen was an “expert in vortex ring state avoidance and the Bell 407 he was flying is virtually impossible to suffer from that phenomenon.”

Wolk said Cullen “was trained at least yearly” in that aerodynamic condition and “taught his students all about it and demonstrated the recovery from it.” He said the NTSB had wrongly “relied solely on training records” in making its determination regarding Cullen.

“This report was a hideous effort to shield the manufacturer, the engine maker and the maintenance facilities from bad design and bad maintenance,” Wolk said.

NTSB spokesman Christopher O’Neil said Wolk’s comments on the findings “are without merit.”

“NTSB investigations and the resulting reports are comprehensive, fact-driven and objective. We stand by our methodology and our report,” O’Neil said.

A spokesman for Bell did not respond to a request for comment.

The helicopter had been hovering near the rally, sending a video stream to authorities, when the troopers were “tasked to provide overwatch for a motorcade” of then-Gov. Terry McAuliffe, according to the NTSB. As Cullen neared the motorcade, the aircraft “began to turn to the right and descend rapidly,” before crashing into nearby trees, investigators said.