OK, here's one about clearance limits.
Suppose you issue me "Cleared direct FIX", where FIX is not part of my original clearance, and with no further instructions.
My understanding is that now FIX is my clearance limit. And the question is, what are you expecting me to do at FIX, absent further communication with ATC? Hold, or try to rejoin my previous clearance in some reasonable way?
This came up years ago when I was flying a Mooney into LAX. LAX was landing to the east, and I was coming from the south, so expecting ILS 7R. About 20 miles out, approach says "LAX is turning the boat around", going to be landing to the west now. OK, I get out the ILS 25L plate as I'm getting vectored out over the ocean while they sort things out. A few minutes later I hear "Mooney 201NV, cleared direct Seal Beach", the SLI vortac, about 15 miles southeast of LAX.
Great! Except now as I'm approaching SLI, I'm realizing: SLI was not part of my original clearance, which was given based on when LAX was landing the other way. So, technically, SLI is now my clearance limit. Am I really supposed to hold there, waiting further clearance? If I proceed past SLI, am I busting my clearance? Asking approach for clarification would be good, but he's dealing with a sky full of other airplanes that are also getting their clearances changed and there's no way to get a word in.
Thinking about it for another minute, I decide that if approach wanted me to hold at SLI they would have said so, SLI is a published initial approach fix for LAX ILS 25L so that's probably the flow they are feeding me into, best thing to do is just depart SLI on the 335 radial to join the approach as charted.
And sure enough a couple minutes after SLI, approach gives me "201NV, contact tower when established on the localizer, cleared ILS 25L approach", almost as if I knew what I was doing the whole time
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Anyway, I think back on this as a situation where trying to fit into an expected flow of traffic worked out better than getting tied up in a technical interpretation of a rule. If you're really bored you could maybe comment on the scope and limts of that as a general approach to flying IFR
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--Paul