I remember when 100 Sqn were complaining about the Hawk nav kit in the concept of LL intercept training over the North Sea. The only bit of nav kit they had - TACAN - was no good at 500ft 50 miles off the coast. They got pi**ed off with the procurement chain and the Eng Authority not working at an answer that they requested the authority to purchase hand held GPIs.
They were refused, on the grounds that the units would have to be procured through the normal channels and trialled by Boscombe. Lead time was quoted in years, so they went out and bought several from Sqn funds anyway!
They didn't have to be accurate to the last metre, but at least it gave them a fighting chance to provide a reasonable position [I don't know how well they worked - I was not on the Sqn].
I am somewhat surprised that the subject of the dodgy nav kit was not discussed amongst the ships Execs. Even further surprised that the Exec Cadre did not do the same and buy one out of their own pocket, knowing just how much of a career stopper is running aground or getting lost.