Pilot Rob Hill, along with his companions Seth Dawson and Liz Redling, died last year when his single-engine plane crashed into Mount Si.
An NTSB report on the Feb. 15, 2012 crash concludes Hill was four times over the legal blood alcohol limit for a crew member aboard a civil aircraft.
According to the report, 30-year-old Hill, 31-year-old Dawson and 29-year-old Redling had attended a local hockey game and then went out to diner prior to the flight
Casey Malone was friends with Redling and said he has been waiting a long time for answers about why the plane went down.
"Where it's a sad day for me to see it's actually related to alcohol, it does bring closure and some kind of finality, I guess," he said.
Malone said he is not condemning Hill, who was an experienced pilot and flight instructor.
"Good people make mistakes," he said. "Hopefully we all can learn from this."
He hopes the tragedy can be a "learning moment" for the high school students who looked up to Hill and Dawson, who were both popular swim coaches in Federal Way.
"If it can save one life by hearing this message, don't get behind the wheel if you even think you've had too much to drink," Malone said.