R.P.G.Collinson was chief systems engineer and later manager of the Flight Automation Research Laboratory of GEC Avionics Ltd. (now part of BAE Systems), in Rochester, Kent, UK. The Laboratory has been responsible for many innovative systems and techniques which have subsequently been used in the development of avionic equipment for many current European and United States aircraft. During his time with GEC Avionics, he also served as manager of the Flight Instruments Division and the Inertial Navigation Division. He was a Chartered Engineer and Fellow of The Institution of Engineering and Technology (The IET) and the Royal Aeronautical Society. Following service in the Royal Navy, he studied electrical engineering at London University, graduating with a First-Class Honours Degree. He was awarded the Silver Medal of the Royal Aeronautical Society for his contribution to the research and development of advanced avionic equipment. Following his retirement, he gave numeroustalks on avionic and aviation topics to lay and technical audiences and presented specialist lectures at two [...], R P G Collinson passed away on 16th February 2022 just as Edition 4 was nearing completion. With the kind permission of the publisher, Edition 4 has been completed by his sons M R Collinson and S W Collinson and technically reviewed by C Bartlett, former Chief Technologist, BAE Systems, Rochester, Kent.