02 JUN 2009 _______________________________________ Detritus of Air France flight floating on Atlantic Ocean >From Wednesday's Globe and Mail, Tuesday, Jun. 02, 2009 09:35PM EDT Unravelling the grim mystery of Air France's Flight 447 will require months of painstaking investigation and - more than in most crashes - the detailed accounts of the doomed aircraft's last few fateful minutes digitally recorded by two black boxes now lying on the ocean floor. On Tuesday, search aircraft and ships found the grim detritus of the destroyed aircraft - a few floating seat cushions, some debris, an oil slick - in two widely separated patches in roughly the same area where a passing pilot thought he saw flickering flames on the water in the hours after the Paris-bound Airbus 330 vanished Sunday night. No survivors were spotted and there is no lingering hope of finding any. The deaths of all 228 passengers and crew aboard the Airbus 330 make the crash the worst aviation disaster in more than seven years. Finding the so-called black boxes is often difficult, especially with crashes at sea. Locating them in a 7,000-metre deep patch of the Atlantic presents an daunting challenge. Both bright-orange recorders, located in the tail of the aircraft, are designed to withstand the crushing pressure of the ocean, and will emit a locator signal for up to 30 days. If the locator beams can be detected, remotely-piloted submersibles will be launched, and - using claw-like probes - will attempt to find, free and recover the recorders. It has been done before. In 1985, after a terrorist bomb blew Air India's flight 182 out of the sky - killing all 329 people, most of them Canadians, on board - the Boeing 747s two recorders were recovered from a depth of more than 2,000 metres off the Irish coast. It took less than three weeks to find and recover the two recorders. After the Swissair crash off Peggy's Cove, N.S., in 1998, the Canadian navy used a submarine to detect the locator beacons, which were then recovered by salvage experts. The Air France crash location is far more remote but may be no deeper than the Air India crash site. If the electronic beacons can be detected, recovery should be possible. The two recorders - one tapes the last 30 minutes of cockpit conversation and the other contains 25 hours of flight instrument and systems data - should allow investigators to reconstruct a precise and detailed picture of the last minutes of Flight 447. Although the pilots' last communication with air traffic control was routine, the cockpit voice recorder should reveal whether they knew they were flying into a string of massive thunderstorms. Such storms are common in the tropics and pilots usually thread their way around and between them, using special weather radar to detect the massive columns, even at night. Some meteorologists, who have reviewed the satellite data from Sunday night and plotted the track followed by Flight 447, believe the aircraft may have flown straight into a huge storm "The satellite imagery indicates that numerous cumulonimbus towers were rising to at least 51,000 feet, and were embedded in extensive stratiform anvils with tops of 35,000 to 45,000 feet,'' said Tim Vasquez, of Weather Graphics. Flight 447 was flying at its assigned cruise altitude of 35,000 feet. Pilots are taught never to fly through - or over - thunderstorms, which can rapidly rise. In a detailed analysis, Mr. Vasquez says a particularly violent storm was located only a few kilometres west of the aircraft's estimated track shortly before the last cryptic computer messages were received, indicating something had gone terrible wrong. But although the storm line was big, it was not unusual for the area. Mr. Vasquez, a former military forecaster who has plotted courses for Air Force One, said, "It's my opinion that tropical storm complexes identical to this one have probably been crossed hundreds of times over the years by other flights without serious incident.'' He, too, is waiting to hear what the pilots were saying. "We can almost certainly count on some unexpected surprises once the CVR [cockpit voice recorder] is recovered,'' he said. France, which will lead the investigation because it was a French-registered aircraft that crashed in international waters, said it was sending a ship capable of deep-water exploration to the area. Search aircraft spotted two widely separated debris fields. That might normally suggest a break-up at altitude with bits of the aircraft swirling down at different rates, but the several days between the crash and the discovery of the floating debris makes extrapolation more difficult. The debris was found 650 kilometres northeast of the Brazilian archipelago of Fernando de Noronha, along the flight's intended routing from Rio de Janeiro to Paris. Curt Lewis, P.E., CSP CURT LEWIS & ASSOCIATES, LLC