National Transportation Safety Board investigators have released a preliminary report on the crash of an experimental aircraft that killed four people near Agua Dulce on January 11.

Here’s the NTSB report:

On February 11, 2018, about 10:59 Pacific Standard Time, an experimental amateur-built Cirrus VK-30, N52TH, collided with the ground while maneuvering in the vicinity of Agua Dulce, California.

The private pilot and three passengers were fatally injured. The airplane sustained damage to the fuselage and all the flight control surfaces.

The airplane was registered to and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions existed near the accident site, at the time of the accident, and no flight plan was filed for the flight.

The cross-country flight originated from Henderson Executive Airport (HND), Las Vegas, Nevada, about 1000, with an intended destination of Van Nuys Airport (VNY), Van Nuys, California.

A witness, located in the vicinity of the accident site and accustomed to hearing/seeing air traffic, reported that he observed the airplane flying straight and level, about 2,000 ft to 3,000 ft above the ground.

He stated that as the airplane got closer to the mountains it looked like the wind had pushed the right wing up. The airplane pitched downward into a near-vertical attitude. The witness added that when the right wing lifted, it sounded like the pilot “maxed the engine out.”

The witness further stated there was a distinct difference in engine sound from the first time he saw the airplane and when it went vertical. He did not see any smoke or anything fall from the airplane as it descended towards the ground.

Examination of the accident site revealed that the airplane impacted terrain adjacent to a series of power transmission lines about 2.5 miles southeast of Agua Dulce.

The wreckage was transported to a secure facility for further examination.

The complete investigation into exactly what caused the crash may take up to two years, NTSB Spokesman Eric Weiss told SCVNews.

Cirrus VK-30