On retiring from the RAF, Ernsting became a visiting professor at King's College London (KCL), where he taught a human and applied physiology Master of Science course. Later, KCL asked him to establish a research laboratory. He was active both in research and in training undergraduate and postgraduate students for 16 years. In addition to his position at KCL, he was a visiting professor at Imperial College, London. In 1998, Ernsting was appointed Head of the Human Physiology and Aerospace Medicine Group of the Guy's, King's and St Thomas's School of Biomedical Sciences.
