The GCA (Ground Controlled Approach), or more specifically PAR (Precision Approach Radar), until recently was the main precision approach procedure used by military; in some cases used by civilian flights as well. It consists of a radar controller that gives you continuosly azimuth and vertical path deviations indications toward the runway. It's considered almost reliable as an ILS of Cat.1, which means it's capable of drive you to the Runway with visibility down to ~600 mt and vertical visibility of 2~300 feet.
Requires Civil Aircraft Mod: https://cam.em-key.de
-=Updated 13/05: corrected a couple of errors=-
In this mission you have to scramble to intercept an incoming unknown aircraft. Ground radars lost its contact near the ADIZ and air defence suspects it is a foreign military jet hiding under the belly of a civilian wide body. Your task is to intercept it and persuade to fly out of friendly airspace. It may or may not turn hostile...
After that, you have to land back to your base under inclement weather: ceiling 300ft, visibilty 800mt, rain...
The script is activated via F10 menu, better request the GCA approach 20~40 nm from the airport. Initially the controller will vector you 8~10 nm from runway threshold. Then, on final approach, she will give you indications of your position related to the final approach nominal path (RWY centerline extension and glide path angle of 3°). Contrary of ILS bars, if the controller tells you "slightly right" you have to steer left to correct, or "well below" means that you are below the glidepath and have to decrease your rate of descent.
If your ground track is already toward the centerline she will say "correcting" or nothing, otherwise she will tell you a new heading to steer to correct.
If you are on the centerline course she says "On course", then you have to keep the runway heading corrected for the cross-wind (the controller doesn't know your heading, she can see only your ground track on the radar scope).
Same as the real life, the controller will give you steering corrections based also on rough extimate of the cross-wind.
If you fly outside the margins she will command you to go around, then you can request again another approach.
(more info about PAR here: https://www.faa.gov/air_traffic/publications/atpubs/atc_html/chap5_section_12.html
Notes for who could be interested:
- Unfortunatly I coudn't assign a frequency to the GCA controller because the function "trigger.action.radioTransmission()" is quite slow in response (at least on my rig), probably because of many variables. So i had to use the simpler trigger.action.outSound().
- The real GCA/PAR have two different controllers: "approach" and "final"... it's not simulated.
- the voice I used is the best i could find online for free... My english is awful