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When I design SID or Missed approach procedure with a typical sequence of initial legs like "Climb to 5000 feet on R-123 ABC VOR/DME, turn left/right direct to ABC VOR/DME", the regulation checker of my flight procedure design software (IDS FPDAM) often warn about the below PANS-OPS standard because it considers the leg turning direct to the VOR/DME without track guidance:

3.1.2 Track guidance shall be provided:
b) within 10.0 km (5.4 NM) after completion of turns for turning departures.

Then most of the time I have to assign a specific course to the navaid (VOR Radial or NDB Bearing) for the aircraft to intercept on the way back to the navaid.

I see that if a specific course is not required, the aircraft will turn direct to the navaid on any course which is suitable with its performance. But the aircraft always have track guidance regarding the navaid.

Then, is the software's warning about the leg turning direct to a navaid without track guidance correct or not?

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I see that if a specific course is not required, the aircraft will turn direct to the navaid on any course which is suitable with its performance. But the aircraft always have track guidance regarding the navaid.

In the earlier paragraph you stated: "...most of the time I have to assign a specific course..."

Is it fair to presume that you only get the warning when you do NOT assign a specific course?

I am unfamiliar with the software you are using, but as you pointed out aircraft performance, (speed, angle of bank, etc.) as well as wind, will cause any turn direct to a navaid to vary, perhaps significantly. If you do not specify a radial or ground track to intercept the pilot would track whatever course they rolled out on, or could simply home in on a curving path.

By definition then; if you don't specify a track there can be no track guidance because there is no track to provide guidance to, right?

That being the case, your sentence in bold is incorrect, and the answer to your title question is NO, flying direct to a navaid (without a track specified) is not considered a leg with track guidance.

I think that is what the software warning is trying to tell you. Does that make sense?

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  • $\begingroup$ An FMS wants to see a sequence of magenta lines from point to point to point. If the procedure is to overfly AAAAA and then turn toward BBB and where-ever that turn finishes (uncertain due to unknown winds & TAS & etc), go from there to BBB, then that clean sequence of points & legs between them isn't defined at the outset. While various FMC's can do various things (like RF legs), it sounds like the rules the OP has wants "and then intercept course ### to BBB" as the solution there. (I'd expect defining AAAAA as fly-past rather than fly-over might work too.) $\endgroup$
    – Ralph J ♦
    Aug 18, 2021 at 21:05
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The problem with “turn direct” is that depending on the aircraft speed and the wind speed/direction, the ground track may be completely different.

This appears to violate the rule requiring “track guidance”, which from your problem I assume means defining a single fixed track over the ground for every flight, regardless of speed or wind. That is presumably to limit the terrain/obstacle clearance surface to something manageable.

It would appear that your choices are to (for an RNAV procedure) move the direct-to waypoint closer than 10 miles or (for a non-RNAV procedure) specify a radial to intercept within 10 miles.

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  • $\begingroup$ IRL 10miles offers quite a strech to wander around if no radial or bearing is specified. You would eventually end up at the specified waypoint, but I, for example, would prolly fly quite a dogleg on the way 🤣 $\endgroup$
    – Jpe61
    Aug 19, 2021 at 15:56
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On a direct-to (DF), there is no track guidance. Any deviation from the line between the original initiation point and the target fix / beacon, will not be corrected for. The aircraft is just steered towards the target. This offers little obstacle protection.

Direct-to-Fix (DF) navigation leg

Instead, a track-to (TF) or course-to (CF) will provide track guidance. If there is lateral deviation from the line defined by the track-to or course-to, the guidance system will steer the aircraft back on the original line.

Track-to-Fix (CF) navigation leg

Course-to-Fix (CF) navigation leg

Images from the FAA Traffic Flow Management learning centre

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