Complex sentence: Once a member of the Royal Air Force has reached the rank of Warrant Officer or Master Aircrew, they are eligible to apply to be a SWO, however there are a few cases of Flight Sergeants acting in the posotion of SWO.
Split into simpler sentences: Once a member of the Royal Air Force has reached the rank of Warrant Officer or Master Aircrew, they are eligible to apply to be a SWO. There are a few cases of Flight Sergeants acting in the position of SWO.