In the ATC, a Group Captain is the OC (Officer Commanding) of a Region.
As the name suggests, a Wing Commander is generally the Officer Commanding of a Wing.
The third rank in the diagram above is Squadron Leader. Officers who hold this rank are either given command of Areas within Wings, or given specific responsibilities within a Wing.
In the Air Training Corps, a Flight Lieutenant is usually the Officer Commanding of a Squadron.
Flying Officers and Pilot Officers are often Squadron Officers who hold specific responsibilities, for example, IC Duke of Edinburgh's Award or IC Adventure Training.
NCO (Non-Commissioned Officer) Ranks
Visit 2175 (Rolls-Royce) Squadron's website to see NCO Ranks of the ATC.