Currently being incorporated into the GR9/9A is the Successor Identification Friend or Foe (SIFF) system. SIFF is an electronic question and answer system that can discriminate between friendly and hostile forces. An interrogator sends a coded radar signal to unidentified targets, and a transponder responds automatically with a coded reply.
BAE Systems as prime contractor is carrying out an 'incremented upgrade', turning the current Harrier GR7/7A to the GR9/9A. But Qinetiq is playing a key role in supporting the acceptance into RAF service, producing the evidence for Military Aircraft Release Recommendations.
Roger Dilley, Qinetiq's Harrier account manager, says the Harrier team had to review their working practices in order to meet the tight programme. "
Source: Flight Daily News