| No. 4 Operational Training Unit RAAF | |
|---|---|
 Vultee Vengeance dive bomber at Williamtown, c. 1943 | |
| Active | 1942–44 |
| Country | Australia |
| Branch | Royal Australian Air Force |
| Role | Operational training |
| Garrison/HQ | Williamtown, New South Wales |
| Engagements | World War II |
| Aircraft flown | |
| Bomber | Vultee Vengeance |
| Trainer | CAC Wirraway |
No. 4 Operational Training Unit (No. 4 OTU) was an operational conversion unit of the Royal Australian Air Force (RAAF) during the Second World War. It was formed at Williamtown, New South Wales, in October 1942 to train pilots and wireless air gunners to operate Vultee Vengeance dive bombers. The school was equipped with Vengeances and CAC Wirraway aircraft. Accidents were common in operational conversion units and No. 4 OTU suffered several fatal crashes during its existence. It was disbanded in April 1944, handing Williamtown over to No. 5 Operational Training Unit.