The 12-minute audio has been pieced together from tapes dating back to the day of the incident itself.
One of the most notorious unsolved crimes in American history, the hijacking - which occurred on November 24th, 1971 - began when a man, who identified himself as Dan Cooper, boarded Northwest Orient Airlines Flight 305 to travel from Portland to Seattle.
During the trip, Cooper called over one of the flight attendants and asked them to write out a note declaring that he had a bomb in his briefcase and that the plane was being hijacked.
When the aircraft stopped at Tacoma International Airport, he allowed the passengers to leave in exchange for four parachutes and the sum of $200,000 in cash.
After the plane had taken off again, Cooper strapped the bag of money to himself, put on one of the parachutes and jumped out somewhere between Seattle and Reno. No trace of him was ever found.
Now, though, long-lost tapes containing the actual audio recordings of the flight crew and air traffic controllers communicating at the time of the hijacking have been revealed to the public.
The audio is from the time that the plane had landed at Tacoma and Cooper was still aboard.
The voices in the recording are mostly those of Captain William Scott, Co-Pilot Bill Rataczak and Northwest Airlines' Director of Flight Operations Paul Soderlind.
It also mentions Al Lee, the Chief Pilot for Northwest Airlines in Seattle who was tasked with fulfilling Cooper's ransom demands.
The recording, which lasts around 12 minutes, offers a unique perspective on the events of that day.