Keith,
yes, it does get complicated, but only because of the age old debates. It's pretty clear in the regs. There is always doubt and confusion when it comes to complex procedures, which is what leads to the debates, but the alphabet police won't excuse us for not knowing or being unsure. If something goes wrong you become liable when you break the "technically" correct rules and I would rather understand which side of that line I am on at all times.
To answer your questions,
- "what is gained by going to the airport first, then proceeding to an IAF?"
It is the legally correct thing to do and all approaches are easily accessible from there.
- "if you're /A or /U, how are you supposed to navigate from MZB to SAN before proceeding to an IAF?"
it is the pilot's responsibility to plan that last direct leg regardless of equipment, in this case the MZB133003 at or above the MIA (i would cheat and take V317 to LOC, but that option's not always available). The pilot is responsible for getting to/from the ATS if he is not on a published procedure or ATC procedure to/from the runway. This is via an 'unpublished route segment' with minimum altitudes defined in §91.185(c)(2)(ii) (and §91.121(c) and §91.177).
- "However, it's less clear if the last fix is not on an approach."
In actuality it is clear according to the regs. You have to remain on your cleared route if in IMC conditions until beginning an approach from your clearance limit. You can only start an approach before reaching the clearance limit if you were advised by ATC to expect an approach, and you encounter a fix that begins that approach before you arrive at your clearance limit. That's it. If passing an IAF without an expect clearance, you must continue to the clearance limit.
Yes emergency authority and common sense can override, but you have to justify these things in the post incident interview and I would still want to know what's correct.
§91.185 IFR operations: Two-way radio communications failure.
(a) General. Unless otherwise authorized by ATC, each pilot who has two-way radio communications failure when operating under IFR shall comply with the rules of this section.
(b) VFR conditions. If the failure occurs in VFR conditions, or if VFR conditions are encountered after the failure, each pilot shall continue the flight under VFR and land as soon as practicable.
(c) IFR conditions. If the failure occurs in
IFR conditions, or if paragraph (b) of this section cannot be complied with, each pilot shall continue the flight according to the following:
- (1) Route.
- (i) By the route assigned in the last ATC clearance received;
(ii) If being radar vectored, by the direct route from the point of radio failure to the fix, route, or airway specified in the vector clearance;
(iii) In the absence of an assigned route, by the route that ATC has advised may be expected in a further clearance; or
(iv) In the absence of an assigned route or a route that ATC has advised may be expected in a further clearance, by the route filed in the flight plan.
(2) Altitude. At the highest of the following altitudes or flight levels for the route segment being flown:
- (i) The altitude or flight level assigned in the last ATC clearance received;
- (ii) The minimum altitude (converted, if appropriate, to minimum flight level as prescribed in §91.121(c)) for IFR operations;
(3) Leave clearance limit.
- (i) When the clearance limit is a fix from which an approach begins, commence descent or descent and approach as close as possible to the expect-further-clearance time if one has been received, or if one has not been received, as close as possible to the estimated time of arrival as calculated from the filed or amended (with ATC) estimated time en route.
- (ii) If the clearance limit is not a fix from which an approach begins, leave the clearance limit at the expect-further-clearance time if one has been received, or if none has been received, upon arrival over the clearance limit, and proceed to a fix from which an approach begins and commence descent or descent and approach as close as possible to the estimated time of arrival as calculated from the filed or amended (with ATC) estimated time en route.
] from there)? I'm pretty sure this may have actually been used as an example in the workshops, but honestly there's hours of video - no chance I'd be able to find it.