IEC 62396-3:2013(E) provides guidance and furthermore it provides necessary requirements for those involved in the design of avionic systems and equipment and the resultant effects of atmospheric radiation-induced single event effects (SEE) on those avionic systems. The outputs of the activities and objectives described in this part of IEC 62396 will become inputs to higher level certification activities and required evidences. It builds on the initial guidance on the system level approach to single event effects in IEC 62396-1:2012, considers some avionic systems and provides basic methods to accommodate SEE so that system development assurance levels are met.