According to the TNI-AU's Chief of Staff Marshal Ida Bagus Putu, the RoKAF Tiger IIs are virtually in the original specification as delivered from Northrop in the 1970s, unlike the TNI-AU's fleet, which underwent an avionics upgrade in the 1990s. It was felt that the difference in configuration would add a burden to the maintenance cost.
Indonesia operates the survivors of 12 F-5Es and 4 F-5F two-seaters delivered in 1980. The aircraft underwent an upgrade in the 1990s, Belgium's SABCA installing new avionics offering commonality with the TNI-AU's F-16s and Hawk 109/209s, rewiring, structural repairs on at least one aircraft and a radar upgrade. This improved the F-5s air combat and ground attack capability, and enabled the type to serve as a lead-in trainer for the F-16s.
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