The pilot who crashed a Cessna 172 plane last year into Mount Si in North Bend that killed himself and both passengers, including Kentlake High School swim coach Seth Dawson, was intoxicated, according to a factual report issued by the National Transportation Safety Board (NTSB).

Pilot Rob Hill, 30, swim coach at Federal Way’s Decatur High School, had a blood alcohol level of 0.15 percent, according to the report issued last month. The Code of Federal Regulations prescribed by the Federal Aviation Administration (FAA) prohibits civil aircraft pilots from flying if their blood alcohol level is 0.04.

The FAA’s Civil Aeromedical Institute in Oklahoma City, Okla., performed toxicology tests on Hill.

NTSB investigators determined that “the on-site examination of the airframe and engine revealed no evidence of a mechanical malfunction or failure with the airframe or engine prior to impact,” according to the factual report.

Elizabeth Redling, 29, of Federal Way, also was killed in the Feb. 15, 2012 accident. The three were on a “personal sightseeing flight,” according to the report. The plane crashed at about 1:54 a.m. after leaving the Renton Municipal Airport at about 1:35 a.m.

The three went to a Seattle Thunderbirds hockey game earlier in the night at the ShoWare Center in Kent and then out to dinner, according to the report.

The NTSB issued a preliminary report a few days after the accident and the factual report last month. A final probable cause report is expected to be issued later this month, according to the NTSB website.

The airplane fragmented upon impacting trees and up-sloping mountainous terrain, which resulted in substantial structural damage,” according to the report. The fuselage was found upside down.

Hill had a commercial pilot certificate and a flight instructor certificate. He had accumulated 991 hours of flight time.

Dawson, 31, was in his second season of coaching the Kentlake boys swim and dive team. He coached the Kentlake girls team in the fall of 2011. Hill had been the Decatur swim coach for five years.

According to the report, Christiansen Aviation, Inc., of Wilmington, Del., the plane’s registered owner, leased the plane to AcuWings, a Renton flight school.

The flight originated from Renton Municipal Airport, but no flight plan was filed. A NTSB crash investigator said there is no law that requires a flight plan for a sightseeing personal flight.

A review of FAA recorded radar showed the aircraft had an initial climb out of Renton to 2,400 feet mean sea level as indicated by its altitude encoding transponder.

“Initially, the aircraft proceeded in a northeasterly direction,” according to the report. “However, as the aircraft approached Snoqualmie Falls, it descended to 1,500 feet and proceeded on an east-southeasterly course. The last radar hit occurred at 1:46 a.m., at which time the aircraft was about 1 mile southwest of the falls, and about 1 mile north of Interstate 90. During the last minute of recorded flight, the aircraft’s ground speed decreased from about 112 to 106 knots.”

Dawson grew up in Vancouver, Wash., where he was a state championship swimmer at Hudson’s Bay High before competing on scholarship at California State Bakersfield.

In 2009, Dawson was coaching boys and girls high school swim in Corbett, Ore., but decided he wanted to move closer to home and took a position with Valley Aquatics, a club team that uses pools in Federal Way, Auburn and Puyallup. Hill also coached at the club.