List of Royal Air Force Conversion Units

Conversion Units and Operational Conversion Units (OCU) were training units of the Royal Air Force.

History
With the introduction of the new heavy bombers, the 4-engined Short Stirling, Avro Lancaster and Handley Page Halifax, into service, the Royal Air Force introduced Heavy Conversion Units. The Heavy Conversion Units began forming in late 1941 to qualify crews trained on medium bombers to operate the heavy bombers prior to assignment to an Operational Training Unit to gain experience before final posting to the operational squadrons.

After the end of the war their role was taken over by the Operational Conversion Units. Although the units had nominal bases it was usual for different flights and individual aircraft to be detached nearer the operational bases. Some of the Heavy Conversion Units were involved in bombing operations over Germany.

Royal Air Force Operational Conversion Units (OCU) are training units that prepare aircrew for operations on a particular type or types of aircraft or roles. Some OCUs have a Shadow or reserve squadron designation which is used if the unit has a war role.