Fix to Fix Nav.

[hawg2hawk]

Not RNAV

After a little more research, the fix-to-fix is outlined in AFI 11-217 (the USAF instrument flight manual) as a departure or terminal procedure. That's when I remembered that every fix-to-fix I've ever done (or seen) has been within the service volume of one TACAN, e.g., from the DLF 030015 to the DLF 180025, never between TACANs, although that would be possible if the volumes overlapped enough.
I'd research more, but that's about the extent of my interest in a procedure I use once every 18 months whether I need to or not.
I do know how to do one, mini, and if you are still interested let me know and I'll try to find a visual representation and a good explanation. There has to be a FAIP out there somewhere with this on a powerpoint slideshow. If not I'll do my best to explain it.
But it is most emphatically not RNAV.

 

[Swede]

Just to elaborate, what she is referring to is a basic "rule of thumb" to derive a heading (and update it continuously) to take you to a radial/DME point. You must be tuned to the VOR/DME in question. That, and an HSI, is all you need.

Let's say you are 40 miles due west of the WAG VOR/DME, thus on the 270 radial for 40 NM. Your current heading is irrelevant. You now want to proceed to the WAG030/80. Any doofus could track inbound to WAG, then outbound on the 030, but the technique she mentioned is a direct routing.

Now it gets tricky and I will not be able to correctly relate it as it's been FAR too long and skills perish. Essentially, one examines the relationship between the head and tail of the bearing pointer, then applies the DME to generate an initial heading. You point the AC on that heading, fly a few miles, then do the mental exercise again. It will give you an updated heading. You continue this way until you magically cross the WAG030/80, flying more or less directly from your previous point.

My understanding is that it is NOT an IFR-approved technique, just a handy tool. It was used in the AF as a mental exercise and helps the student understand all of the TACAN relationships and how the HSI works.

There MUST be a T38 FAIP who can get more specific.

 

[hawg2hawk]

My understanding is that it is NOT an IFR-approved technique, just a handy tool.

11-217 says it is an IFR technique.

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[font=TimesNewRoman,Bold]7.10. Proceeding Direct to a VOR/DME or TACAN Fix. [/font]To proceed direct from one fix to another is often required during departures, approaches, or when maneuvering in a terminal area. Bearing and range information from a VOR/DME or TACAN facility is sufficient for navigating direct to any fix within reception range.

For the full description, go here:

http://www.e-publishing.af.mil/pubfiles/af/11/afman11-217v1/afman11-217v1.pdf

And look on page 127/128.


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