Any software used in the control of a safety critical application is termed 'high integrity' software. This term is applied to the software if a malfunction in the software could a hazardous condition. The air transport industry is dependent on public confidence and a good safety record. Regulations and guidelines are in place to help provide that confidence. However, as technology moves on so does the pressure on these documents. The presentation will address existing avionic safety standards, their objectives and the evolution of the standards with imminent technology changes.