We had two sets of needles with both showing glide path and line up. One was like an ILS and was just a transmitter. The ACLS needles were actually a data link between the ship and the aircraft. With ACLS if you had a good autopilot and good auto-throttles you could “couple up” with the ship and the computers would do the work. Approaches to the ship are straight-ins at night or in bad weather. You normally approached the needles from below and the left so when they sent the initial signal to the aircraft you would see your needles up and to the right. Before the controller on the ship actually locked up the ship and the aircraft he would say, “say your needles” and if your response was “up and right” you both knew it was providing valid glide slope and lineup information to the aircraft and you would “couple up”.
In my time not too many guys would actually couple up but they would have both sets fo needles displayed as a crosscheck (one in the HUD and the other on the ADI) or they might fly it to about a mile or so. It took a LOT of man hours to keep them up and on occasion it would “burp” and scare the $hit out of you with sudden pitch down or some other weird control input....not good at night. 😳
Our AT’s massaged a Tomcat for several days and I flew it up to Patuxent River for some tests. Before the test pilots got in it do their thing I had to fly a half a dozen coupled approaches to touchdown so they could check the telemetry between the aircraft and their transmitter. It was impressive; the whole plane was just quivering all the way down the glide path. There are much better systems in use today; “Magic Carpet” is exponentially better.
