November 27, 2013
Airbus is offering incentives for A320-family operators to upgrade legacy flight management guidance computers (FMGCs) with newer systems designed to prevent runway overruns, according to a European Aviation Safety Agency (EASA) bulletin.
The program, in place since mid-summer, targets about 385 older A319s, A320s and A321s currently in service. The program replaces FMGCs with updated logic and Runway Overrun Warning/ Runway Overrun Protection System (ROW/ROPS).
The improved systems also eliminate a long-known hazard identified as “spurious thrust increase during approach,” in which the plane’s auto thrust function can increase thrust during an overly fast approach.
Investigators believe this is what happened to an Air Mediterranee Airbus A321 that landed too fast in a dense fog and overran Runway 36R at Lyon Saint Exupery Airport on March 29. The aircraft stopped about 300 meters past the runway end. All 174 passengers and seven crew members evacuated safely.
“At this stage of the investigations, it is identified that the main contributor to this runway overrun was a non-stabilized approach not followed by a go-around,” the EASA bulletin says.
“Auto thrust misbehaviour in case of large overspeed led to an unexpected thrust increase, which is considered as a contributor to the long flare,” the safety agency adds.
Airbus identified the auto thrust problem in 1996, and began offering the FMGC upgrade to correct the issue in 2001.
The aircraft, delivered in 1997, is not equipped with the upgraded FMGC logic or ROW/ROPS.
“It has been determined that the ROPS function . . . would have triggered a «RUNWAY TOO SHORT» aural alert before touchdown,” EASA says.