main dog:
Some international airports (Paris CDG for one) publish notes specifying you do exactly that: in CDG you turn on final automatically if on a vectored heading within 70˚ (if memory serves) of inbound course, provided you were previously informed you were being vectored for that localizer and you can't get a word in edgewise.
However in absence of such specific local rules, I would be very wary of wavering from any clearance in such a busy environment... you'd
certainly get LAX APP's attention though, can't argue with that
, but I don't think it's the kind of attention you'd be happy to get
.
But, there is
not an absence of specific "local" rules. The rules I cited in Post #4 apply to the entire United States. They don't apply to Paris or Rome or Lima.
Here is the official FAA AIM current and free of charge:
http://www.faa.gov/air_traffic/publications/atpubs/aim/
You will note it is arranged by chapters so you easily find the cites I set forth in Post #4.
Chapter 5-4-3 for instrument approaches.
Chapter 5-4-23 for visual approaches.