The pilot who flew a single-engine plane into the side of Mount Si last year, killing himself and two passengers, was intoxicated, according to findings by the National Transportation and Safety Board (NTSB).

A factual report published last month on the Feb. 15, 2012 accident found that pilot Rob Hill had a blood alcohol content of 0.15 percent, nearly four times the 0.04 allowed for a crew member on a civil aircraft, according to the findings. The factual report is written in preparation of the NTSB’s final report.

Hill, 30, was an experienced commercial pilot and flight instructor at AcuWings flying school in Renton. According to the company officials, he took one of the flight school’s planes at the Renton Municipal Airport without permission for a late-night flight.

Baha Acunar, the co-owner and executive vice president of AcuWings, said Hill had a set of keys to the flight school’s office and took the plane without signing it out, apparently planning to “borrow” it for the evening

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Hill, along with friends Seth Dawson, 31, and Liz Redling, 29, took off around 1:30 a.m. after attending a local hockey game and going out to dinner, according to the report.

Redling posted photographs of herself and Hill in the plane on a social-network page less than an hour before the crash.

The NTSB determined that Hill, who had nearly 1,000 hours behind the controls, flew into the side of the mountain, near North Bend, in the dark. Both wings and the rudder were sheared off the Cessna 172 by trees before it slammed upside down into the steep hillside, board investigators found.

The crash occurred at 1:54 a.m., according to the NTSB.

NTSB investigator Wayne Pollack said the plane was flying under nighttime visual rules, in which flying without contacting air traffic control is permitted and not unusual.

Hill and Dawson both coached on the Valley Aquatics Swim Team in Federal Way and at local high schools. Hill also coached at his alma mater, Decatur High School in Federal Way.

“This is just so sad,” said Casey Malone, who was a friend of Redling’s. He said nearly 1,000 people showed up at her funeral.

“This was not an accident. It was a crime,” he said. ”Losing a friend like this is difficult.”

Mike Carter:

or 206-464-3706