An abnormal heart condition was also listed as a possible contributing factor.
According to the report, Dahl died at a friend's house in Lakewood on May 25. She was 52.
Her husband, Jason Dahl, was the captain of United Airlines Flight 93 when it crashed in Shanksville, Penn. on Sept. 11, 2001.
She was a former flight attendant with United Airlines and watched the events of that day play out on television.
After 9/11, Dahl devoted her life to provide financial assistance for young pilots. She also worked on tributes and memorials for 9/11 victims and raised her children.
She founded the Captain Jason Dahl Scholarship fund that is awarded annually to college students majoring in aviation.
As of 2011, 16 students have been awarded scholarships. Some have already become commercial pilots.