APNewsBreak: Airspeed systems failed on US planes

APNewsBreak: Airspeed systems failed on US planes

By JOAN LOWY
Associated Press Writer


WASHINGTON (AP) -- On at least a dozen recent flights by U.S. jetliners, malfunctioning equipment made it impossible for pilots to know how fast they were flying, federal investigators have discovered. A similar breakdown is believed to have played a role in the Air France crash into the Atlantic that killed all 228 people aboard in June.

The discovery suggests the equipment problems are more widespread than previously believed. And it gives new urgency to airlines already scrambling to replace air sensors and figure out how the errors went undetected despite safety systems.

The equipment failures, all involving Northwest Airlines Airbus A330s, were brief and were noticed only after safety officials began investigating the Air France crash - on a Rio de Janeiro to Paris flight - and two other recent in-flight malfunctions. The failures were described by people familiar with the investigation who spoke only on condition of anonymity because they were not authorized to comment publicly.

While a car's speedometer uses tire rotation to calculate speed, an airplane relies on sensors known as Pitot tubes to measure changing air pressure. Computers interpret that information as speed. And while a car with a broken speedometer might be little more than an inconvenience, many airplane control systems rely on accurate speed information to work properly.

Like the fatal Air France flight, the newly discovered Northwest incidents and the two other malfunctions under investigation all involved planes with sensors made by the European electronics giant Thales Corp. The Air France crash called into question the reliability of the sensors and touched off a rush to replace them.

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I think we have a contributing factor to the Air France crash.

it also affects the vertical airspeed and altimeter.Obviously not a good situation....I don't know how these problems would occur unless there's a problem with the sampling tubes to these gages. I guess the issue is that these are linked to sensors/computer, not analog gages like in a Cessna which create another level of complexity altogether.