Simplify the following text for a Grade 8 native English-speaking person.
Original: No. 3 Fighter Sector ( 3FS ) was a Royal Australian Air Force ( RAAF ) unit formed at Townsville Grammar School , Townsville , Australia on 25 February 1942 .
Simplified: No. 3 Fighter Sector ( 3FS ) was a Royal Australian Air Force ( RAAF ) unit during World War Two .