IEC PAS 62396-6:2014(E) details the mechanisms and conditions that produce \'extreme space weather\' (ESW) and the changes within the avionics environment under such conditions. Consideration is given to the impact and risks of ESW on passengers and crew travelling on aircraft in flight and the option for in flight monitoring of the environment. Avionics electronics and systems operating during flight can be affected under such conditions and these are reviewed. By testing of complete equipment for extreme space weather tolerance, the degree of robustness to ESW can be assessed. In the PAS, flight related infrastructure (not the aircraft itself) that can be affected or disabled by an extreme space weather event is identified.