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June 15, 2010

Control Issues in Libya Crash

Filed under: Incidents — aerotowfeeq @ 4:41 pm
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Disoriented pilots who failed to follow basic safety procedures are believed to have caused last month’s crash of a Libyan airliner that killed 103 people, according to people familiar with the investigation.

Preliminary data gathered by an international team of investigators, these people said, indicate the pilots lost control of the Afriqiyah Airways Airbus A330 after breaking off their landing approach to Tripoli and starting to climb away from the airport.

The accident, at the end of a flight from Johannesburg, is prompting Airbus to step up efforts to devise foolproof automated ground-collision avoidance systems, these people said. The enhanced safeguards are specifically intended to prevent the kinds of mistakes that apparently occurred in Tripoli, in which confused pilots got out of sync with the plane’s computerized controls and ended up flying an apparently functioning commercial jet into the ground.

Such ground-collision avoidance systems are likely to take years to perfect and install on new Airbus models, and they still must overcome skepticism from many pilots and regulators. But the work under way highlights Airbus’s efforts to develop cockpit-automation features designed to take control of aircraft as a last resort to keep them from flying into obstacles when pilots lose control or lack awareness of their location.

Pilots depend heavily on autopilots and flight-control systems to climb, navigate and land planes, and they also rely on automation to issue warnings about obstacles and other hazards. Airbus increasingly is looking at how computer systems could instantly seize control when pilots ignore audible or visual cockpit warnings. Creating a fail-safe solution is challenging because, to avoid nuisance warnings, some existing safety systems and devices are designed to turn off just before an airplane prepares to land.

By linking existing onboard crash-prevention devices with other advanced cockpit instruments, the goal is to have computers actually carry out evasive maneuvers if pilots fail to respond to automated warnings. In the wake of the Sept. 11, 2001, terrorist attacks, Airbus engineers devised a system to take control of jetliners to keep hijackers from using them as weapons, by preventing the planes from flying into buildings, for example. But the systems were never deployed.

Airbus is installing onboard crash-prevention protection on its superjumbo A380 models, but those systems are aimed only at preventing midair collisions if pilots fail to follow automated warnings to change altitude.

The latest Airbus development would represent a nearly foolproof way to prevent crashes caused by pilots getting confused or losing track of their position—rather than those caused by mechanical or other equipment malfunctions. Airbus’s effort to take automation to a new level contrasts with rival Boeing Co.’s continuing focus on pilot judgment and a pilot’s option to disregard or override automated commands in all circumstances.

When Afriqiyah Flight 771 crashed on May 12 in good weather and daylight less than a mile from the airport, the only survivor was a 9-year-old Dutch boy. Information from the plane’s flight-data recorders has been downloaded by investigators, though the results haven’t been made public. The pilots didn’t report any problems to air-traffic controllers during the approach, Libyan officials have said.

It is too early to draw definitive conclusions, but Libyan investigators and Airbus officials say they believe the wide-body jet was working properly. A statement released by Libya last month said there was “no sign indicating a technical failure.”

A spokesman for Airbus, a unit of European Aeronautic Defence & Space Co., said the company on Friday sent update notices about the investigation to all operators of A330s, but declined to give details.

A person familiar with the communication said it told airlines that investigators’ analysis indicates the crashed plane, which was only nine months old, had no system malfunctions, still had sufficient fuel going to its engines, and didn’t suffer a fire before impact.

When the jet was at roughly 1,000 feet in altitude and about a minute from touching down, according to people familiar with the details, the pilots reacted to some type of ground-proximity warning. The co-pilot, who was flying, increased power quickly and pulled up the nose of the plane, typically the correct steps to initiate a so-called go-around. But since there weren’t many passengers aboard and the jet had relatively little fuel, it accelerated rapidly. The captain, according to people familiar with the sequence of events, may have been looking at charts or was distracted by something else.

At that point, the co-pilot apparently believed the Airbus A330 was climbing at a dangerously steep angle and pushed the nose down, quickly losing control of the plane. The captain subsequently tried to yank the nose up again when he heard more collision warnings, but the big plane was too close to the ground for such maneuvers, these people said. That scenario is consistent with the widely scattered, small pieces of wreckage found at the site.

In recent years, so-called loss of control accidents—usually prompted by confusion involving computer controls—have become the No. 1 killer in commercial aviation world-wide.

Too many pilots “are getting tied up in knots in their automation,” Bill Voss, head of the Flight Safety Foundation, told an industry conference in Tucson last month. Sometimes, pilots get distracted and pay less attention to basic flight rules while grappling with complex computer programs. In other instances, crashes have been caused by crews simply failing to understand what computers were commanding the plane to do. Considering the early data from the Libyan crash, Mr. Voss told the participants, “You have to start wondering what happened” with the plane’s computers.

John Cox, a former U.S. airline pilot who now consults on safety matters, said the airline industry isn’t paying enough attention to training aimed at preventing “low-speed, loss-of-control accidents close to the ground.”

The lessons from such crashes, he told the same industry conference, “aren’t being learned; we’re not adequately addressing this.”

In the U.S., aviation regulators, pilot unions and safety experts are engaged in a debate over how to update simulator training to better prepare pilots to deal with aerodynamic stalls and related emergencies.

In principle, the broader collision-avoidance system that Airbus is currently focused on would have prevented the pilots of a Polish air force jetliner carrying senior government officials, including the president and his wife, from crashing their Tupolev 154 during an attempted landing in bad weather at a military airfield in Smolensk, Russia, in April. The cockpit crew ignored repeated automated warnings that the plane was too close to the ground. All 96 people aboard were killed.

According to its proponents, the Airbus system also could have prevented several other fatal crashes in recent years that stemmed from pilots losing control of their aircraft.

The pilots of an Air France plane that crashed in the Atlantic Ocean on a flight from Rio de Janeiro to Paris a year ago may have been overwhelmed by alarms in the cockpit and become disoriented amid stormy weather and strong turbulence, experts say. All 228 people aboard the plane died.

Although the plane’s data recorders haven’t been recovered, automated maintenance messages sent by the Airbus A330 moments before it disappeared indicate that its speed sensors malfunctioned and the plane suffered a cascading series of system failures. But those problems, by themselves, shouldn’t have caused the jet to crash. Other planes have faced similar malfunctions and emerged without incident.

The crash of a Yemenia Airways jetliner just weeks after the Air France crash also appears to have resulted from pilot disorientation. Pilots of the Airbus A310 were on approach to Moroni, Comoros, at night amid heavy winds and apparently hadn’t adequately prepared for the landing, according to investigators. The plane crashed in the Indian Ocean, killing all but one of the 153 people aboard.

A similar accident occurred in May 2006, when an Armenian Armavia flight was approaching the airport in Sochi, Russia, over the Black Sea in bad weather. After lengthy discussions with the control tower about whether to attempt a landing, the crew approached the airport, but at the final moment decided not to land on that try. The pilot became disoriented during the climb and pointed the Airbus A320 downward, investigators said. It crashed, killing all 113 people aboard.



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    Comment by how much should i weigh — June 20, 2010 @ 9:34 am | Reply

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