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Fix to Fix Nav.

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minitour

Well-known member
Joined
Apr 17, 2004
Posts
3,249
Was on a flight before christmas with a delightful (read: HOT!) young lady in the Air Force (Trainer on 707 variants). We got to talking about flying (I was studying for the Comm oral) and she was telling me about Fix to Fix nav and how it's not as hard as it sounds. If I had some paper, she would have shown me how to do it, but...unfortunately, I'm never prepared.

Anyone know how it's done?

If I was able to navigate that way and had two VOR recievers and an ADF (no GPS or DME) could I file IFR from XYZ airport direct ABC fix direct DEF fix for an approach? I realize that I may not get ABC direct DEF, but I'd like to avoid the hassle of having to file XYZ airport direct 123 VOR (15 miles the other way), then the victor airway, when there's a fix about 5 miles northeast of the field that's ON the victor airway...this is all assuming non-radar, so no vectors on course.

I can't see why I can't file that, since I have the required nav radios (vor navigation), but I've always been told "no, you have to file to a VOR first so you know where you're at".

Anyone?

-mini
 
Shure, you just make shure that you are within the station distances (low, high, terminal) at the right altitude.
 
I've filed to a radial/DME before...lotsa times.

Say I wanted to use the SPS 018 radial at 30DME for my point along the route. The entry on the flight plan (we use DD-175) for that point looks like this: SPS01830

Maybe it's done a little differently in the civ world. I dunno.

I suppose you could file IFR from point to point, creating a route as a series of fixes...but why would you want to? Ugh...just use victor airways or go direct as much as possible until you reach your terminal area...THEN do a fix to fix as necessary. Don't make it hard on yourself :)
 
minitour said:
Was on a flight before christmas with a delightful (read: HOT!) young lady in the Air Force (Trainer on 707 variants). We got to talking about flying (I was studying for the Comm oral) and she was telling me about Fix to Fix nav and how it's not as hard as it sounds. If I had some paper, she would have shown me how to do it, but...unfortunately, I'm never prepared.

Anyone know how it's done?

If I was able to navigate that way and had two VOR recievers and an ADF (no GPS or DME) could I file IFR from XYZ airport direct ABC fix direct DEF fix for an approach? I realize that I may not get ABC direct DEF, but I'd like to avoid the hassle of having to file XYZ airport direct 123 VOR (15 miles the other way), then the victor airway, when there's a fix about 5 miles northeast of the field that's ON the victor airway...this is all assuming non-radar, so no vectors on course.

I can't see why I can't file that, since I have the required nav radios (vor navigation), but I've always been told "no, you have to file to a VOR first so you know where you're at".

Anyone?

-mini

Sure. But unless your aircraft has an HSI with a bearing pointer (with a head AND a tail), it's more trouble than it's worth.
 
minitour said:
If I was able to navigate that way and had two VOR recievers and an ADF (no GPS or DME) could I file IFR from XYZ airport direct ABC fix direct DEF fix for an approach? I realize that I may not get ABC direct DEF, but I'd like to avoid the hassle of having to file XYZ airport direct 123 VOR (15 miles the other way), then the victor airway, when there's a fix about 5 miles northeast of the field that's ON the victor airway...this is all assuming non-radar, so no vectors on course.

I can't see why I can't file that, since I have the required nav radios (vor navigation), but I've always been told "no, you have to file to a VOR first so you know where you're at".

Anyone?

-mini

I see what you're talking about now...I think. Let me see if I got this right. You want to use cross tuning to define fixes instead of VOR/DME? If so, you can ONLY file to those fixes if they are defined by cross tuning (although they'll also be defined by DME, as well...probably).

If there's a VOR/DME fix on an IAP, you can't just "come up" with a cross-tuning solution for the fix. For example, if you're looking for the initial approach fix that's, for example, the R162/10DME, you can't find another VOR nearby and plot the radial that intercepts that fix UNLESS it's depicted on the plate. Otherwise, you're basically doing TERPS work yourself. I don't know about you, but that stuff is way beyond my paygrade. :)

For enroute fix-to-fix, I'm really not sure about what you can/can't file if you're operating sans-DME. I'm more used to working with TACAN, so it's a luxury we always have. Sorry.
 
You don't have the necessary equipment to go fix to fix using just 2 vors and an adf. What you probably didn't gather from your conversation with the hottie is that she was probably describing an RNAV system to you. Anyways, ATC would not give you anything that was fix to fix since your equipment type would not indicate RNAV capable.
 
RNAV is what I thought... actually a pretty cool navigational tool.. used it quite a bit when i was flying w/o GPS or Loran. you can pretty much place your waypoint anywhere along your route of flight.
 
Maybe it was an RNAV kind of "system" she was talking about...I was too busy staring at her chest to catch a lot of details *im a pig*.

Not that it's a big deal here, because we get vectors on course, but I was wondering that if radar went down, if I could file the fix that's to the north of us (it's on the Victor Airway and defined by cross-radials and DME) as the first point of my flight plan rather than XYZ (vor) V123 DEF(vor). Instead it would be MYFIX V123 DEF...if that makes sense.

I realize that without an RNAV or GPS system of some sort, I can't really go from fix to fix...more of an initial fix type thing...

Oh well...it was worth asking. Thanks for the info!

-mini
 
Wasted said:
You don't have the necessary equipment to go fix to fix using just 2 vors and an adf. What you probably didn't gather from your conversation with the hottie is that she was probably describing an RNAV system to you. Anyways, ATC would not give you anything that was fix to fix since your equipment type would not indicate RNAV capable.

Not true.

The fix-to-fix is a part of every USAF instrument checkride that I've ever been a part of, and it does not require RNAV, just a TACAN receiver. T-38 students used to do them all day long and twice on sundays and a TACAN was the only NAVAID IN the thing.
And you can file a fix-to-fix and ATC will approve it -- as long at it is just one fix to fix. If you try to go fix to fix to fix to fix, that is apparently considered RNAV, and ATC will not approve it without the appropriate RNAV equipment.
Now.
I know this to be the case because I have filed many and done many over the years, and I have had this explained this way to me by several AIS (advanced instrument school) grads in several squadrons, because I have wondered the same thing many times. But I have never seen it written anywhere, nor have the AIS guys ever provided written documentation. In my opinion, it's really only useful as an instrument proficiency exercise, and I think that's the reason it's taught to begin with. I have never used one in "real life" with or without RNAV, nor have I ever filed for one except for an instrument check.
 
Last edited:
RNAV is fun!

If you have GPS, FMS, Manual RNAV, or LORAN, you can file direct to a fix. You can also file fix to fix.

TACAN and VOR (manual RNAV) functions by triagulating the waypoints position compared to the aircrafts current position from the VOR. It also adds in the current track of the aircraft to add the third side of the "triangle". The RNAV then computes the Desired Track, and gives you that heading to fly. Wind correction is almost always included. Only VORs are needed for this function. One or two depending on the waypoint location. Old RNAV is limited to reception range. ADF, LORAN, GPS, or WAAS can be added for further accuracy.

Hope this helps Mini!
 

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