Hi Baigar,
As I remember it, the BAe Hawk T Mk 1 in RAF service had the "AHRS" as an upgrade to the flight instrumentation in about 1981. The fit was referred to as "A-hars" by the aircrew, and was a very good upgrade of the original Hawk attitude system which toppled in aerobatics. Generally, the aircraft with the A-hars upgrade were much preferred by the pilots. Cheers
OAP