PN,
What ME nav stream?
Given the planned OSD for the GR4, and the imminent folding of the F3 fleet about to provide some spare FJ WSOs, surely we can't be many years away from turning off the GR4 WSO system anyway? What little we need is also supposed to be going out to contract (MFTS) which presumably will mean the RAF no longer providing Dominees/Tucanos as such.