IEC 62396-1:2012(E) is intended to provide guidance on atmospheric radiation effects on avionics electronics used in aircraft operating at altitudes up to 60 000 feet (18,3 km). It defines the radiation environment, the effects of that environment on electronics and provides design considerations for the accommodation of those effects within avionics systems. This International Standard is intended to help aerospace equipment manufacturers and designers to standardise their approach to single event effects in avionics by providing guidance, leading to a standard methodology. This International Standard includes the following technical changes with respect to the previous Technical Specification: - Guidance has been provided on the environment for altitudes above 60 000 feet (18,3 km) and the effects on electronics are documented; - a new Annex has been added to provide late news as of 2011 on SEE cross-sections applicable to the atmospheric neutron environment. Keywords: avionics, atmospheric radiation, electronic equipment