The new Airbus A320 airliner sits on the tarmac, 22 February 1987, during his first test flight, in Toulouse, becoming the first aircraft to fly with digital computer-driven fly-by-wire controls and side-stick controllers. The Airbus A320 airliner, a significant sales success and a technological trailblazer, is one of the most produced airliner in the world. (Photo credit should read JEAN-PIERRE MULLER/AFP via Getty Images)
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Approximately 6,000 Airbus aircraft will be grounded to undergo a critical software update to avoid potential data corruption that can interfere with safe operation in flight.
On Friday, November 28, Airbus stated: “Airbus has worked proactively with the aviation authorities to request immediate precautionary action from operators via an Alert Operators Transmission (AOT) in order to implement the available software and/or hardware protection, and ensure the fleet is safe to fly. This AOT will be reflected in an Emergency Airworthiness Directive from the European Union Aviation Safety Agency (EASA).”
The FAA followed immediately with a similar Emergency Airworthiness Directive directed at US operators.
The directives cover the entire A320 family including the smaller A319 as well as the A320 and A321 narrowbody aircraft which are the workhorses of the global fleet. For 5,100 of the aircraft, the software can be updated in about three hours. However, for many of the remaining 900 aircraft, onboard flight computers may have to be replaced potentially causing delays in the system depending upon availability of the “black boxes.”
The action hits in the middle of the busy Thanksgiving weekend of which Sunday is typically the busiest travel day of the year.
Impact on carriers has been different, depending upon the airline. Air France reported delays out of Charles de Gaulle airport in Paris, but Easyjet, American and Delta, all of which operate A320 fleets, were largely unaffected.
The issue was discovered during an ongoing investigation of an October 30 incident where a JetBlue aircraft enroute from Cancun, Mexico to Newark, New Jersey unexpectedly pitched downward forcing an emergency landing at Tampa International Airport. 15 passengers were taken to hospitals for treatment of injuries associated with the incident.
Airbus discovered that intense solar radiation could corrupt onboard data used to calculate the aircraft’s altitude. Unlike Boeing designs, Airbus aircraft utilize “fly by wire” technology whereby control surfaces are commanded to move electronically and cannot be overridden by the pilot.
SEATTLE, WA – NOVEMBER 18: Boeing 737 Max airplanes sit parked at Boeing Field on November 18, 2020 in Seattle, Washington. The U.S. Federal Aviation Administration (FAA) today cleared the Max for flight after 20 months of grounding. The 737 Max has been grounded worldwide since March 2019 after two deadly crashes in Indonesia and Ethiopia. (Photo by David Ryder/Getty Images)
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The Boeing 737 series (a narrowbody competitor analogous to the A320) still uses mechanical devices to move control surfaces, however the newer Boeing 777 and 787 utilize fly by wire technology. However, pilots can override the computer commanded flight controls through excessive force on the yoke.
Airbus aircraft have side stick controllers instead of yokes and limit the pilot’s actions to prevent “departing the envelope” of safe flight operation. Problems with faulty data or flight control computers commanding movements have been a factor in many accidents including the Lion Air and Ethiopian fatal crashes of the Boeing 737MAX in 2018 and 2019.
In the October JetBlue incident, the autopilot never disengaged, despite the violent drop in altitude. At the time, the cause was thought to be a faulty Elevator and Aileron Control (ELAC) of which there are a primary and back up on Airbus aircraft. The elevator is the horizontal movable part of an aircraft’s tail that controls pitch (nose up or down). The aileron is a hinged movable part of an aircraft wing’s trailing edge and controls roll allowing it to bank for turns.
Criticism of the computer control aspect of fly by wire technology has been existent since its inception. On June 26, 1988 a brand new Airbus A320-111 crashed during the Habsheim Air Show in Germany. The aircraft made a low pass over the field but impacted trees at the end of the runway in front of thousands of spectators. The pilot, who was found culpable for the accident, claimed that the computer prevented him from applying thrust to pull the aircraft up to avoid the trees. Three people were killed due to smoke inhalation.