To allow an aircraft to fly with so many items of equipment with just a "switch on" release is an airworthiness issue. The performance of TANS can only be regarded as "unknown" because the perfomance of the sensors feeding it were "unknown".
As an ex-Boscombe Down trials officer, who fully understands the limitations of a "switch on" release, I am surprised that this machine was allowed to taxi around the airfield.
DV