Airbus says it managed to expedite software replacement in many of the 6,000 A320s pulled from service to counter a bug that makes their flight control systems potentially vulnerable to intense solar radiation. The possible fault was discovered when a JetBlue A320 experienced an uncommanded drop in altitude on its way from Cancun to Newark almost a month ago. It diverted to Tampa to get 15 people treated for injuries. Subsequent investigation revealed that solar flares might mess with the code in the control system. “Analysis of a recent event involving an A320 Family aircraft has revealed that intense solar radiation may corrupt data critical to the functioning of flight controls,” Airbus said in a statement. The sun is in a period of intense solar flare activity, resulting in satellite communications disruptions and vivid displays of the aurora borealis as far south as Texas.
Airbus issued an Alert Operators Transmission (AOT) in advance of an expected Emergency AD issued by the FAA after one was released by the European Aviation Safety Agency and adopted by regulators worldwide that grounded the affected aircraft. “The subsequent investigation identified a vulnerability with the ELAC B hardware fitted with software L104 in case of exposure to solar flares. This identified vulnerability could lead in the worst case scenario to an uncommanded elevator movement that may result in exceeding the aircraft structural capability,” The Air Current quoted the AOT as saying. It was expected to take about three hours to either roll back the software that governs operation of the elevator or swap out the whole computer involved and replace it with a computer that has an earlier version of software but Airbus was able to supply a much quicker fix in many cases.
Most airlines worked through the issue over the weekend but there were still some AOG A320s late Sunday. The emergency action will affect almost half of the active aircraft in the A320 family and there were some disruptions. American Airlines told USA Today it got an early jump on fixing the 340 affected aircraft in its fleet and most were done over the weekend. “Though we expect some delays as we accomplish these updates, we are intently focused on limiting cancellations—especially with customers returning home from holiday travel,” the airline said in a statement.
I’m still wearing my tin hat…
You should wear your seat belt, too…
I have done some work under the DO-178B (Airborne Systems and Equipment Certifications). There are two major circumstances that would get into this circumstances: Data corruption and Pointer Corruption. I strongly suspect that data corruption is the problem; any program loop should handle data extremes through filtering. Pointer corruption is more likely. Instead of having a fixed address for a routine, the routine addresses are assigned at startup and stored in a table. If that address is corrupted then the address pointer will go out into the weeds.