The Apollo ADL604 LORAN bolted beneath the Nav's radar was a very accurate system in GW1 but as we got the cheap version it tended to have fits of the vapours above 150 kts.
And there was no pilot display.
And all the information was displayed on a couple of lines of green LED dots.
And there was no training other than the Nav reading the 400 page manual.
And it was an utter bastard to use...
But apart from that, what have the Romans ever done for us?