Why it has been de-activated if it was so reliable ? (useless ?).
I think it has got to do with the fact that when this was manufactured in the 60s, there were no electrical PFDs and NDs that could identify the runway electrically and this was the only equipment that could at that time. Now, there is the PFD, ND and the EFB's rotating airport map layout that could confirm your a/cs runway and it's orientation to it, causing it to become obsolete.