we do need to understand the nav systems
I dare say the crew thought much the same. Flt Lt Tapper had to resort to visiting Racal to try to work out SuperTANS. (An extraordinary event - the details of which should be available in both Racal and MoD files). He probably found it disconcerting to be told the Error messages were “meaningless” and that there was no longer any indication of how accurate GPS was – yet the same system in the Mk1 was apparently still ok. He probably wanted to know what changes had been made during Mk2 conversion, as no-one in MoD had bothered telling him. Given that single simple fact, under MoD’s own rules the aircraft should not have been released to service. That is why any inquiry should always start with this question to ACAS – “Why?”.