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COMMENTARY: Aging aircraft were coping with wear

By GEORGE JONAS

JULY 26 -- Flight AF-4590 crashed shortly after takoff from Charles de Gaulle airport at 4:44 p.m. Paris time on Tuesday. Had Air France's sleek Concorde continued, the airliner would have grown some nine inches in length after it reached crusing altitude somewhere in the stratosphere around 55,000 feet. The expansion would have been caused by the heat of its supersonic airspeed of about 2.0 Mach, or 2207 kilometres per hour.

The outside wall of the cabin would have felt warm to the touch. Even in the brisk minus 56 degrees Celsius that reigns in the lower reaches of outer space, the friction would have heated Flight AF4590 at the "hot spot", the jet's nose, to a toasty 127 degrees C. But the thrust from the spectacular deltawing jet's four Rolls-Royce/SNECMA Olympus engines would have carried its 100 passengers and 9 crew from Paris to New York in a little over 3hours.

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The world's only supersonic airliner is old news in aviation. John F. Kennedy was still U.S. president when French and British design teams joined forces to produce a supersonic civilian transport in 1962. The prototype plane, 001, first flew in March, 1969. It first reached supersonic speeds in October of the same year.

The partnership between British Aerospace and Aerospatiale of France produced 14 Concordes over the decades that followed. They were expensive to fly, for the airlines as well as for passengers, but they were elegant, fast, and safe. None of them ever had a fatal accident. Until yesterday, Air France and British Air each had seven operational "Speedbirds" (as air traffic controllers call Concordes) in their fleets.

After yesterday, there are thirteen left.

Just as sailing ships reached the pinnacle of their development around the time when steam ships where making their first clumsy appearance, Concordes were state-of-the art-expressions of an older aviation technology.

The supersonic marvel that has become synonymous with luxury and sophistication in international travel, has no "glass cockpit". It has none of the up-to-date avionics that make the flight deck of the Airbus resemble a computer game. For the most part, the Concorde still boasts the kind of old-fashioned instrumentation pilots call "steam-engine gauges."

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But with its speed, comfort, and service, not to mention its separate and superior terminal at airports, the Concorde is an aeroplane that reminds travellers of what air trasportation used to be in the dim past of a more civilized era, before it became mass transportation. Technologically as well as in sheer convenience, the Concorde represents the apex of a bygone period.

When I flew the Concorde from New York to London in the early 1990's, a ticket still cost a mere $7000 instead of the current $9875. I was on assignment, and fortunate enough to be invited on the flight deck.

The Concordes in the British fleet have always been commanded by rather senior airmen. Our captain was so senior that he wore trifocals.

Along with the grey fringes on his domed forehead, his looks and demeanour created the impression of an Oxford don rather than a flyboy.

But the skipper was a true aviator. When his first officer disdained the automated flight director and hand-flew a beautiful climb profile after takeoff, the captain turned to me in the jump seat to make sure I didn't miss the spectacle. "He's showing off for you," he said, with an unmistakable flyboy's twinkle behind his trifocals.

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The flight engineer was proud of the intricate pumps required the keep the Concorde's delicate balance in the thin air of high altitudes. As fuel is burned, the pumps keep shifting the remainder to maintain the plane's required centre of gravity. If the pumps ever failed, the three-men crew would have to engage in some fancy footwork to slow the jet down and lose altitude in a hurry, two tasks that normally work against each other.

During our flight, the warning lights above one set of pumps started to flicker. The captain and the flight engineer agreed that it was nothing to worry about. "Did the same thing on the way over," the flight engineer said. "It's all pretty old stuff, you know," he added defensively, tapping his finger on the glass face of the instrument.

Old stuff is right. Even then the Concorde was getting long in the tooth. After 31 years the fleet was aging. Only a few month ago micro-cracks were found in the wings of both the French and British planes. Last week British Air reportedly grounded one of its Concordes to fix a three inch (76 millimetre) crack.

At this time it's impossible to say what went wrong with Flight AF-4590. Any theorizing about a cause can only be speculative. Even when informed, speculation can be misleading.

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Still, the account of one expert eyewitness, a Fedex courier pilot named Sid Hare, who happened to be looking out the window of a nearby hotel, points to a possible uncontained engine failure. He saw the plane trailing smoke and fire right after takeoff.

"It raised its nose, then stalled and then rolled over and fell to earth in a huge fireball," Hare told CNN television. "It appeared to be a catastrophic engine failure."

Ironically, Air France President Jean-Cyril Spinetta witnessed the accident from his office window. His description of what he saw is similar to the Fedex pilot's. A still photograph of the doomed plane right after takeoff plainly shows a plume of fire from the left engines. This also confirms Hare's account.

When something fractures inside a jet engine -- a rare occurence -- it's possible for pieces to penetrate the outer shell. The projectiles can then enter the cabin structure or an adjacent engine. Shrapnel can rupture fuel lines or cells, injure people, or damage another powerplant. It can also disrupt control structures or surfaces, from hydraulic lines to ailerons, rendering the aircraft unflyable. In 1989 such a failure resulted in the crash of to a United DC-10 at Sioux City, Iowa.

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At no point is a flying machine more vulnerable than at takeoff. It has neither much flying speed nor altitude. It needs to convert whatever airspeed it has to more altitude to avoid rising terrain or obstacles. As a plane climbs, it needs all the power from its healthy engines to avoid slowing to a point of aerodynamic "stall", i.e. below the minimum speed it requires to fly.

That's why engine failure at takeoff is dangerous. Uncontained failure-that is, failure that damages other structures or other engines is often fatal. The Concorde, depending on its weight, needs an airspeed of about 180 knots (333 kilometres) just to maintain level flight, let alone to climb.

If the plane was trailing fire and smoke at takeoff, the sign of a possible engine failure, it may have stalled as it attempted to climb. "Stall" in this sense doesn't mean engine stoppage. It's an aerodynamic condition. A stalled wing has the flying characteristic of a brick. In the case of a plane, it can be a brick hurled at the ground at 333 kilometres an hour.

All this is speculation. The engine wouldn't have had to fail to start a fire; it could have ingested a flock of birds. Even sabotage can't be ruled out at this point. We only know that for 100 German tourists who chartered the plane for a dream holiday, as well as for four people on the ground, the end was unexpected, tragic and sudden.

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(George Jonas is a writer, columnist and pilot, who writes for the Southam newspapers in Canada.)

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