Washington, August 08: On at least a dozen recent flights by US 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 authorised 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.
Many companies, however, simply replaced them with another Thales model. As it became clear the problem was more widespread, Airbus and European regulators told companies to replace at least two of the three sensors on each plane with models made by North Carolina-based Goodrich Corp. The planes are allowed to continue flying while the switch is made.
Thales officials declined to comment. The company has previously said its sensors were made to Airbus specifications.
The Northwest incidents were discovered when Delta Air Lines, which merged with Northwest last year, reviewed archived flight data for its fleet of 32 Airbus A330s, the people close to the inquiry said. All of the incidents took place in the Intertropical Convergence Zone, which extends from 5 degrees north of the equator to 5 degrees south, and all the planes involved landed safely, they said.
–Agencies