Tester you say,
It does work on the aircraft - those in the know can read the 41(R) OpEval and Advice to Aircrew reports which followed BAES trials last year.
,
This seems to be at variance with what MoD and others are saying. It may be working on the aircraft but there appears to be problems with integration. The IFF mode 4 worked on the aircraft back in 2003, but it was not correctly integrated.
DV