• 10 disasters that changed aviation – Part I

    • Image credit: Joe Pugliese
    • United 173: Crashed 10 km short of the airport. Image credit: AP/Wide World Photos
    • Air Canada 797: After an emergency landing, the DC-9"â„¢s doors were opened, fuelling an on-board fire with an influx of air. Image credit: AP/Wide World Photos
    • Delta 191: most survivors were in the tail section, which broke free. Image credit: Corbis
    • Aeromexico 498: the crash destroyed 11 houses in Cerritos, a Los Angeles suburb. Image credit: AP/Wide World Photos
    Date:30 September 2007 Tags:, , , ,

    Flying in a jetliner is extraordinarily safe. There has been only one fatal crash in the United States in the past five years, an astounding record considering that more than 30 000 flights take off there every day. How did flying get to be so reliable? In part, because of accidents that triggered crucial safety improvements. Here are eight crashes and two emergency landings whose influence is felt – for the good – each time you step on a plane.

    Grand Canyon
    ATC and FAA

    The TWA Super Constellation and the United DC-7 had taken off from Los Angeles only 3 minutes apart, both headed east. Ninety minutes later, out of contact with ground controllers and flying under see-and-avoid visual flight rules, the two aircraft were apparently manoeuvring separately to give their passengers views of the Grand Canyon when the DC-7’s left wing and propellers ripped into the Connie’s tail. Both aircraft crashed into the canyon, killing all 128 people aboard both planes. The accident spurred a R1,75 billion upgrade of the air traffic control (ATC) system – serious money in those days.

    (It worked: There hasn’t been a collision between two airliners in the United States in 47 years.) The crash also triggered the creation in 1958 of the Federal Aviation Agency (now Administration) to oversee air safety.

    Cockpit teamwork

    United Flight 173, a DC-8 approaching Portland, Oregon, with 181 passengers, circled near the airport for an hour as the crew tried in vain to sort out a landing gear problem. Although gently warned of the rapidly diminishing fuel supply by the flight engineer on board, the captain – later described by one investigator as “an arrogant S.O.B.” – waited too long to begin his final approach. The DC-8 ran out of fuel and crashed in a suburb, killing 10.

    In response, United revamped its cockpit training procedures around the then-new concept of Cockpit Resource Management (CRM). Abandoning the traditional “the captain is god” airline hierarchy, CRM emphasised teamwork and communication among the crew, and has since become the industry standard. “It’s really paid off,” says United captain Al Haynes, who in 1989 remarkably managed to crash-land a crippled DC-10 at Sioux City, Iowa, by varying engine thrust. “Without (CRM training), it’s a cinch we wouldn’t have made it.”

    Lav smoke sensors

    The first signs of trouble on Air Canada 797, a DC-9 flying at 10 000 m en route from Dallas to Toronto, were the wisps of smoke wafting out of the rear lavatory. Soon, thick black smoke started to fill the cabin, and the plane began an emergency descent. Barely able to see the instrument panel because of the smoke, the pilot landed the plane at Cincinnati. But shortly after the doors and emergency exits were opened, the cabin erupted in a flash fire before everyone could get out. Of the 46 people aboard, 23 died.

    The FAA subsequently mandated that aircraft lavatories be equipped with smoke detectors and automatic fire extinguishers. Within five years, all jetliners were retrofitted with fire-blocking layers on seat cushions and floor lighting to lead passengers to exits in dense smoke. Planes built after 1988 have more flame-resistant interior materials.

    Dallas/Fort Worth
    Downdraught detection

    As Delta Flight 191, a Lockheed L-1011, approached for landing at Dallas/Fort Worth airport, a thunderstorm lurked near the runway. Lightning flashed at 300 m, and the jetliner encountered a microburst wind shear – a strong downdraft and abrupt shift in the wind that caused it to lose 100 km/h of airspeed in a few seconds. Sinking rapidly, the L-1011 hit the ground about one and a half kilometres short of the runway and bounced across a highway, crushing a vehicle and killing the driver. The plane then veered left and crashed into two huge airport water tanks. On board, 134 of 163 people were killed. The crash triggered a seven-year Nasa/FAA research effort, which led directly to the on-board forward-looking radar wind-shear detectors that became standard equipment on airliners in the mid-1990s. Only one wind-shear-related accident has occurred since.

    Los Angeles
    Collision avoidance

    Although the post-Grand Canyon ATC system did a good job of separating airliners, it failed to account for small private planes such as the four-seat Piper Archer that wandered into the Los Ang

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