Engineers investigate effects of space weather on airliners

The company is conducting commissioned research into the phenomenon, developing sensors for advanced warning and designing novel system architectures with better tolerances.

The increase in microelectronics systems in aircraft in the past few decades means that they are potentially more vulnerable to geomagnetic events originating from space.

The main threat to aircraft systems specifically is from neutrons that are created in the atmosphere through the collision of space phenomenon such as solar flares with the Earth’s magnetic field.

‘Think of what’s happening as being rather like the Large Hadron Collider going on all the time at the top of the atmosphere,’ Keith Ryden, senior consultant on space environments and effects, told The Engineer.

‘They [the neutrons] are very penetrating because they’re not charged and they go through the aircraft and into equipment. If they reach a silicon device, because they’re travelling so fast, basically a nuclear reaction happens inside the silicon that causes a certain quantity of charge to be developed.’

Studies have shown that at a very fundamental level this can lead to so-called ‘bit flips’ where a 1 changes to a 0 and a 0 to a 1 in various locations.

This can have a variety of unpredictable consequences but there is evidence to suggest that autopilot systems are particularly vulnerable. During a Qantas Airbus 330-303 flight in Australia in 2008, the autopilot dived twice without warning due to scrambled data, injuring 122 crew and passengers, 13 seriously. Subsequent investigations suggested it could have been a ‘single-event effect’ in the computer caused by geomagnetic activity.

Nevertheless, as Ryden points out: ‘It’s very difficult to pinpoint precisely the evidence saying this is the individual neutron that has caused this particular event.’

Part of addressing the problem will be more research into the phenomenon — a process that began in the 1980s with detectors being deployed on Concorde.

‘It was predicted by certain people with great foresight that these sorts of issues would start to occur in the future, even though they weren’t an issue for Concorde because the electronics were so old,’ said Ryden.

While that was done with large propane gas sensors, newer technology based on solid-state sensors could allow aircraft to employ early warnings — something Qinetiq is actively working on. Pilots might simply instruct passengers to put on their seat belts as with turbulence or reduce altitude slightly to avoid geomagnetic concentrations.

When designing systems, engineers could look at building in greater redundancy and being more selective with components. Research has shown that microprocessor chips vary in their neutron susceptibility by up to 10-fold. 

‘The tricky thing is that manufacturers can change their processes quite a lot without avionics engineers even knowing about it; electrically they’ll do the same function but from this point of view [neutron susceptibility] they change quite dramatically,’ said Ryden.

Ultimately, he hopes that these sorts of issues will become embedded in the industry certification process for new equipment.