IEC/TS 62396-3:2008(E) provides guidance to those involved in the design of avionic systems and equipment and the resultant affects of atmospheric radiation induced Single Event Effects (SEE) on those avionic systems. The outputs of the activities and objectives described in this Technical Specification will become inputs to higher level certification activities and required evidences. It builds on the initial guidance on the system level approach to SEE in IEC/TS 62396-1, considers some avionic systems and provides basic methods to accommodate SEE so that system development assurance levels may be met.