As I understand the latest AFI 11-217, Fix-to-fix is basically verboten:
AFI 11-217 vol. 1 22 Oct 2010 said:
5.8. Proceeding Direct to a VOR/DME or TACAN Fix. Proceeding directly to a radial/DME fix without RNAV equipment is not a normal form of navigation in the NAS. It can, however, be a useful technique for backing up RNAV equipment or navigating in a loss of communication situation. Bearing and range information from a VOR/DME or TACAN facility is sufficient for navigating direct to any fix within reception range.
5.8.1. In order to legally conform to NAS area navigation procedures and the national route program (NRP) as outlined in FLIP GP chapter 4 and FAA AC 90-91, USAF pilots and air traffic controllers should not file, give, or accept a clearance (as applicable) that requires an aircraft to navigate direct to a radial/DME fix (perform a fix-to-fix) except under the following circumstances:
5.8.1.1. The primary navigation equipment onboard the aircraft is either area navigation (RNAV) or advanced RNAV capable and operating normally.
5.8.1.2. Flight will be conducted where radar monitoring by air traffic control (ATC) is available.
5.8.1.3. Locally defined arrival/departure procedures require the navigation to/from a radial-DME fix for the sequencing of aircraft. Locally defined procedures must be evaluated by TERPS and flight checked if flown in instrument meteorological conditions (IMC) and radar monitoring is not available.
5.8.1.4. Operational necessity dictates (i.e. filing and flying an air refueling track) or conforms to military enroute operations.
5.8.2. When operating in the NAS and given a clearance to proceed to a radial/DME fix, unless the aircraft capability or operations meet one of the parameters defined above, pilots should reply with ―unable‖ and state the appropriate suffix code defined in FLIP GP chapter 4. Under these circumstances, ATC should provide navigation guidance to the radial/DME fix either via radar vectors or an alternate routing.
I am unsure whether the last sentence of 5.8.1 ("except under the following cirmunstances") means that you must satisfy ALL of the requirements of 5.8.1.1-5.8.1.4 in order to fly direct to a FIX, or only 1 of the requirements. My sense is that you need only satisfy 1 of the requirements... which means that you could argue that as long as RADAR monitoring by ATC is available, then a Fix-to-fix is legal... But again, I'm not sure if we are supposed to read that as an "AND" or as an "OR."
So I revert to the tone of the 5.8, 5.8.1 and 5.8.2 which certainly makes it seem like Fix-to-Fix is not intended to be a normal or typical practice, and used only in unusual circumstances (at least as a primary means of navigation) such as with certain navigation or communications failures. Based on that verbiage, if I'm flying truly "/A"... I think that the intent is that I don't accept a fix-to-fix.
Kind of sad, especially after teaching them in the Tweet for several years! Of course, I've seen enough of them severely garbaged up to see why ATC doesn't want us doing them, and after the T-6 swap-over the emphasis on teaching them basically disappeared (at least as of a year and a half ago).
When I left AETC, they were only taught to completion in the SIM. In the airplane, you would only do the first three steps (1. Tune, identify & monitor the NAVAID, 2. Dial in the radial of the fix, 3. Turn between the head of the bearing pointer and the desired radial, favoring the radial if the fix's DME is larger than your current DME, or favoring the head of the bearing pointer if the fix's DME is smaller). After that, they would revert to GPS direct, and use the fix-to-fix as a back-up to the GPS... which can be read as "not at all."
