Alot of times we hear the ATC saying fly heading 030 join the localizer inbound without actually clearing the pilot for any instrument approaches. i thought that was some sort of contact approach but then again the pilot must request it so i guess it's not...
Nope, it's not. You'll hear, "track the localizer" quite frequently and here's why:
Remember a clearance consists of 3 basic pieces. Those pieces are ROUTING, ALTITUDE, and CLEARANCE LIMIT. Every clearance contains those parts, but frequently you may not be able to identify all of them. Also frequently the clearance limit is sort of a "who cares?" or a technicality concept. Particularly on vectors.
For example, when you first start getting vectors to an ILS, the controller will say, "these will be vectors for the ILS (that's the clearance limit- up to but not including the ILS), fly heading 020 (routing), and descend and maintain 3000 (Altitude)". Of course the clearance limit part of that doesn't really matter THAT much, because it's not like you are ever going to get to your clearance "limit" and have to hold, since your routing is a vector. And a vector continues FOREVER.
So typically right before starting an approach you'll hear the controller say something like, "Turn left heading 040, descend and maintain 2,200, until established on a segment of the approach, and then cleared the ILS runway 07."
So again, we have the three pieces. Routing was 040 heading and then follow the ILS procedure to the runway to the missed approach procedure (because every clearance for an approach clears you for the missed approach or alternate climbout instructions also). The Altitude was 2,200 and then whatever was published in the instrument procedure, all the way through the missed approach procedure. And the clearance limit was the missed approach procedure.
But sometimes he'll say, "fly heading 040 and track the localizer inbound, descend and maintain 2200".
This means something different. Routing is 040 and then the localizer. But Altitude clearance has changed, since you must stay at 2200. You can't descend yet. Also, your clearance limit is still up to but not including the approach (although this is really more of a technicallity than anything else, since it's not like you'll have to hold at your clearance limit, since he told you to track the localizer).
So the simplest difference is the altitude. "Cleared the approach" means the routing and the altitudes on the approach. "Track the localizer" means follow the localizer, but you're not allowed to descend to the altitudes depicted on the plate yet.
