After years of legal skirmishes, Canadians can finally hear the gripping soundtrack for one of the country's worst aviation disasters.

This memorial is one of the many that have been left over the years at the monument at Bayswater, N.S., to remember the 229 people who perished in the crash of Swissair Flight 111.

The Swissair Flight 111 air traffic control tapes, kept under lock and key since the 1998 tragedy, have been released to the Canadian Press following a tortuous court battle that went all the way to the Supreme Court of Canada.

The hours of recordings include 12 critical minutes, starting as the aircrew reports smoke in the cockpit and ending with a last desperate transmission as the aircraft nose dives at high speed into St. Margaret's Bay, N.S., near Halifax.

"Swissair One Eleven heavy is declaring emergency," says one of the pilots in a heavy Swiss-German accent, as the second pilot makes a nearly simultaneous transmission in the cockpit confusion: "We are declaring emergency now."

The aircraft's fuel tanks were nearly full as it began its transatlantic flight from New York to Geneva on Sept. 2, 1998.

The voices of the Swiss pilots — Urs Zimmermann, 50, and co-pilot Stephan Loew, 36 — become slightly muffled in the recordings when they don their oxygen masks. The official transcripts do not indicate which pilot is speaking at any time.

'We have to land'

Ten minutes later, as smoke billows through the cockpit and a massive electrical failure disables all flight controls, including the lights, there's another harrowing transmission: "Eleven heavy we starting to dump [fuel] now we have to land immediate."

There's a slight urgency in his voice as the pilot makes a final, repetitive transmission: "And we are declaring emergency now Swissair One Eleven."

The MD-11 aircraft, with 229 people aboard, flew for about six more minutes before it slammed nose first and almost upside down into the dark, choppy sea off Peggy's Cove at 10:31 p.m. AT.

As the plane hit the water at about 550 kilometres an hour, everyone aboard died instantly and the fuselage shattered into several million pieces. The tremendous impact caused seismographic needles to flutter in Halifax and Moncton, as if an earthquake had hit.

The recordings add a human dimension to otherwise sterile transcripts, as air traffic controllers and the pilots betray hints of taut emotion while the high-altitude tragedy unfolds.

As the Halifax airport controller attempts to contact the aircraft, there's a final brief radio burst, sounding like someone shouting. Investigators could not determine the source, but the electronic squeal provides an eerie coda to the drama.

Tapes expected to be painful for families

Vic Gerden, the Transportation Safety Board's chief investigator into the crash, said the families of the victims were briefed frequently at the time of the disaster but have not previously heard the audio.

"I don't recall them having the opportunity to listen to the tapes," Gerden, who retired last year, said in an interview from Winnipeg.

Miles Gerety, who lost his brother Pierce in the crash, predicted that hearing the tapes will be painful for families.

"These things bring an event back to people, the family members, who've put a lot of time and distance between the crash … and their losses," he said in an interview from his home in Redding, Conn.

"I think it would be hard to hear."

A four-year, $57-million investigation by the Transportation Safety Board blamed flammable insulation that allowed a small electrical arc fire to spread uncontrolled, melting the cockpit ceiling, shorting out all power and leaving the aircrew helpless.

Within days of the tragedy, the safety board released transcripts of the air traffic control recordings but steadfastly refused to release the audio itself, saying it contained personal information.

John Reid, then Canada's information commissioner, initially supported the refusal. "In my view, the voices, along with the tonal and emotive characteristics constitute personal information of three air traffic controllers and the two pilots," he ruled in 1999.

Information commissioner fought to release tapes

But after receiving complaints about the board's refusal to release ATC recordings for four other air disasters, Reid changed his mind and went to court. He lost at federal court in 2005, but won on appeal in 2006 when three justices dismissed the claim that ATC audio recordings by their very nature contain personal information.

The Federal Court of Appeal also dismissed a claim by Nav Canada, responsible for air traffic control, that such recordings are "commercial" and should therefore be withheld to protect the business interests of the organization.

The safety board and Nav Canada then went to the Supreme Court of Canada but were rebuffed in April when the high court refused leave to appeal.

The board was therefore compelled to turn over the Swissair tapes after an Access to Information Act request from the Canadian Press, which was a complainant in the court action over the four other air disasters.

The high court ruling brings Canada into line with the United States, where ATC recordings have been available to the public for years. Even in Canada, radio enthusiasts have long been able to freely monitor ATC transmissions because open, unencrypted communication among aircraft and ground controllers has been seen as an essential safety measure.

At least one U.S.-based website — liveatc.net  — broadcasts live ATC transmissions from airports around the world, including Toronto, Montreal and Vancouver.

In Canada, cockpit voice recordings of conversations between pilots remain legally unavailable because of privacy rules. The Swissair investigation was hobbled in part because cockpit recording equipment failed in the last few minutes of the flight, apparently due to electrical failures.