No. 1 School of Technical Training (No. 1 S of TT) is the Royal Air Force's aircraft engineering school. It was based at RAF Halton from 1919 to 1993, as the Home of the Aircraft Apprentice scheme. The Aircraft Apprentice scheme trained young men in the mechanical trades for aircraft maintenance, the graduates of which were the best trained technicians in the RAF and would usually progress to Senior NCO ranks. However, ninety one ex-apprentices went on to achieve Air Rank. Many more became commissioned officers, including Sir Frank Whittle "father of the jet engine", who completed his apprenticeship at RAF Cranwell, before the move to RAF Halton. Graduates of the Aircraft Apprentice scheme at RAF Halton are known as Old Haltonians.