You may have heard in the media that the Airbus A320 family of aircraft has been grounded following a software glitch triggered by solar radiation. The incident involved a JetBlue A320 aircraft flying from Mexico to New York on 30 October. During the flight, the aircraft experienced an un-commanded nose-down pitch moment with rapid loss of altitude. The crew recovered control of the aircraft and diverted to Tampa International Airport in Florida, where a number of passengers received medical treatment.
Although details are vague at the moment, Airbus carried out an investigation and identified a vulnerability with the ELACs (elevator and aileron computers) operating on software version L104. It seems that intense solar radiation could corrupt the operation of the ELACs and potentially lead to an un-commanded elevator movement that could exceed the structural limits of the aircraft.
So how could solar radiation affect an aircraft’s electronics? It is known that solar particles can penetrate solid objects, particularly when that solid object is flying through the thin end of our atmosphere. If a solar particle passes through a microchip, it could change the value of a binary digit (bit) from 0 to 1 or vice versa. This phenomenon is known as a single-event upset, and could cause erroneous or unexpected behaviour in the ELAC’s operation.
To their credit, Airbus reacted quickly. They identified the problem, found a solution and issued an Airworthiness Bulletin requiring immediate action to ground affected aircraft until the software had been updated. It seems that the previous version of the software (L103) does not carry the same vulnerability to solar radiation as L104, but it is not publicly known why.
