Expert System - Australian Flags by McGoo Software

Based on the responses you have made:

The flag is probably the Australian Air Force Ensign

Conclusion Notes:

The Air Force Ensign is for use by the Royal Australian Air Force at its facilities in Australia and overseas. The design of the Air Force Ensign has been changed twice since the Royal Australian Air Force was established in 1921. The RAAF used the ensign of the Royal Air Force of Britain until 1949, whereupon the Southern Cross and Commonwealth star were added to the ensign and the British roundel (military aircraft insignia) was moved to the lower fly. During the Vietnam War the RAAF ceased using the British roundel on its aircraft, as Britain was not involved in the Vietnam war and the continued use of the British roundel on Australian military aircraft highlighted its inappropriateness. The central red circle of the British roundel was substituted with a leaping red kangaroo to create a new Australian roundel. The Air Force Ensign with its British roundel, however, was not altered until 1982. The new Air Force ensign with the Australian roundel was proclaimed as an official Australian flag under Section 5 of the Flags Act 1953 on 6 May 1982.

Expert System Rule:

IF on the flag the Southern Cross is visible
AND on the flag there is a Union Jack present
AND the field of the flag is sky blue
THEN the flag is probably the Australian Air Force Ensign.

Calculated Certainty Factor: 0.54 = probably