VOR navigation question

midlifeflyer said:
Thanks you. Appreciate it.

I guess I mean the difference between "you can" and "you may."

While the regs and guidance may leave some arguable wiggle room, I think (assuming no vectoring) that while Airplane A is permitted to fly IFR Direct BREDY with even a single VOR, airplane B requires some form of approved RNAV capability.
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The question is if aircraft B can maintain +/-4 miles of the route centerline. If your ded reckoing is off by 10 degrees (+/-5 deg, which is a pretty generous margin), you will have to fly 45 miles to fall outside the +/- 4 mile protected space. We are not talking about Amelia Earhart type distances. Having said that, I wouldn't do ded reckoning in non-radar mountainous terrain in IMC. But I don't see it as problematic for short distances over flat land to get to an airway intersection.
 
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flyingron said:
GPS has nothing to do with it. And while it is OBVIOUS (which is why the "Huh?") That's not what you said. And you don't even need to be on an airway or established radial. I've gotten clearances that involve taking off and intercepting an airway.
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So explain how I can legally navigate from a departure airport to an intersection on an airway without using radar vectors or GPS? How did you navigate to the airway that you were cleared to intercept?

Are you suggesting I can use dead reckoning to fly IFR from the airport to the intersection?
 
Clip4 said:
Considering MON coming they ought to bring it back because without the magenta line most would be lost.
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Depending on the circumstances, losing the magenta line might be an emergency sufficient to justify relying on 91.3(b) authority to use whatever navigation means you need to in order to bring the flight to a safe conclusion.
 
Flyingfanatic said:
So explain how I can legally navigate from a departure airport to an intersection on an airway without using radar vectors or GPS? How did you navigate to the airway that you were cleared to intercept?

Are you suggesting I can use dead reckoning to fly IFR from the airport to the intersection?
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DR, RV, and assigned headings all appear in SIDs to get people to the en route structure. How do you depart from any airport that's not on an airway?
 
midlifeflyer said:
Thanks you. Appreciate it.

I guess I mean the difference between "you can" and "you may."

While the regs and guidance may leave some arguable wiggle room, I think (assuming no vectoring) that while Airplane A is permitted to fly IFR Direct BREDY with even a single VOR, airplane B requires some form of approved RNAV capability.
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A minor quibble, perhaps, but I think an important one. If I interpret what you're trying to show by the map, Aircraft A is still not going "direct" to BREDY. Rather, they are flying the 030 radial to BREDY. It's effectively almost the same thing, and perhaps even identical in ground track, but not quite identical in application or terminology.
 
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@RussR . On Approaches that have DR Segments, they usually put Hdg on the Chart. Are the headings to intercept on DP's called DR segments, legs or whatever?
 
RussR said:
A minor quibble, perhaps, but I think an important one. If I interpret what you're trying to show by the map, Aircraft A is still not going "direct" to BREDY. Rather, they are flying the 030 radial to BREDY. It's effectively almost the same thing, and perhaps even identical in ground track, but not quite identical in application or terminology.
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Minor quibble accepted.
 
luvflyin said:
@RussR . On Approaches that have DR Segments, they usually put Hdg on the Chart. Are the headings to intercept on DP's called DR segments, legs or whatever?
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Yes, in general terms.

The 8260.3E (TERPS) calls DP segments that are just a heading a "Dead Reckoning" segment. This is also referenced in 8260.46G when listing possible design options.

When talking about leg types (generally for avionics behind-the-scenes coding purposes), these would most commonly fit under VI or VA types. VI = fly a Heading to Intercept (like a course to follow). VA = fly a Heading to an Altitude (then usually turn direct somewhere). There is also the VM, Heading to "Manual Termination", which you wouldn't see on a SID but you do see on STARS all the time - "After AAAAA, fly heading 230, expect radar vectors to final approach course." There are a few other much-lesser-used types, at least in the U.S., as well.
 
RussR said:
Yes, in general terms.

The 8260.3E (TERPS) calls DP segments that are just a heading a "Dead Reckoning" segment. This is also referenced in 8260.46G when listing possible design options.

When talking about leg types (generally for avionics behind-the-scenes coding purposes), these would most commonly fit under VI or VA types. VI = fly a Heading to Intercept (like a course to follow). VA = fly a Heading to an Altitude (then usually turn direct somewhere). There is also the VM, Heading to "Manual Termination", which you wouldn't see on a SID but you do see on STARS all the time - "After AAAAA, fly heading 230, expect radar vectors to final approach course." There are a few other much-lesser-used types, at least in the U.S., as well.
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Thx
 
I recall Machado's Instrument Survival Manual describing that TERPS restricts DR legs on SIAPs to a certain length as they have to allow for massive variations in wind conditions. It is, for all intents and purposes, DR. It's just that you're not calculating the heading to flown, that work is done for you.
 
coma24 said:
I recall Machado's Instrument Survival Manual describing that TERPS restricts DR legs on SIAPs to a certain length as they have to allow for massive variations in wind conditions. It is, for all intents and purposes, DR. It's just that you're not calculating the heading to flown, that work is done for you.
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Yes. The evaluated airspace for a DR segment is huge. It starts 6 nm either side of the heading specified, and widens at 15 degrees to account for wind. They have a maximum length of 10 nm before you must have intercepted the next course (radial/localizer).
 
coma24 said:
I recall Machado's Instrument Survival Manual describing that TERPS restricts DR legs on SIAPs to a certain length as they have to allow for massive variations in wind conditions. It is, for all intents and purposes, DR. It's just that you're not calculating the heading to flown, that work is done for you.
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The same is true of MEA gaps. The permitted length of the gap increases with altitude but there is just so much distance we can be trusted with DR.
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Although, when it comes down to it, many of us do (perhaps the better word is "did" before GPS) treat it as a course and calculate a rough heading. When it comes right down to it, the outbound leg of every holding pattern is DR.
 
Clip4 said:
I guess I can. When I got my instrument rating Dead Reckoning appropriate for IFR navigation was requirement under 61.65(b). Used to file to an intersection on an airway as the first fix, but it also was like eight mile from the departure airport.
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I used to fly a bit with a Navy Doctor in his J-Bonanza (pre GPS era). He had a gadget in his panel that enabled one to "move" a Vortac any where you wanted it. Just select the radial and DME to the fix and hit enter. Just follow the CDI to the middle-of-no-where fix. Easy as pie.

Along those lines, I and my fellow pilots had that situation departing Eglin AFB, KVPS, via an intermediate intersection, and join the Victor air way at a Vortac to the NE. Our A/C had a single VHF nav, no GS receiver and no DME. Sure we could ask "Wolfcall" (APC) for vectors, but that would label that pilot as a person of no consequence. Some did, recognizing their short comings.
It was easy to flip between two other nav aids left and right of course and read the radials off the tail of the RMI arrow. Nailed it every time. Army Aviators are known for their fast hands.
 
flyingron said:
Don't have one, but the FAA guidance certainly mentions such is possible.
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Now that we know that 'headings' in DP's are in fact 'Dead Reckoning Segments', post #51, there would probably be hundreds, maybe thousands of them. Pilot isn't doing any Dead Reckoning though, he's just flying an assigned heading. The Approach designers are the ones who done did the 'reckoning.'
 
luvflyin said:
Now that we know that 'headings' in DP's are in fact 'Dead Reckoning Segments', post #51, there would probably be hundreds, maybe thousands of them. Pilot isn't doing any Dead Reckoning though, he's just flying an assigned heading. The Approach designers are the ones who done did the 'reckoning.'
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What about an airway gap? If I had corrected for wind prior to entering the airway gap, I would not take out the wind correction while transiting the gap.
 
aterpster said:
What about an airway gap? If I had corrected for wind prior to entering the airway gap, I would not take out the wind correction while transiting the gap.
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Yeah. Pilot would be doing the ‘reckoning’ on that. Just holding your holding heading would be the obvious way to do it. If you were ‘chasing’ the needle when you lost the signal though, it could be interesting.
 
flyingron said:
DR, RV, and assigned headings all appear in SIDs to get people to the en route structure. How do you depart from any airport that's not on an airway?
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Back when I got my IFR rating ( pre-GPS) I was taught to go from the airport direct to a VOR to join an airway. (VOR’s being much more plentiful) There was no DR unless it was a SID, that I recall.

Thankfully, GPS has solved this problem.

I guess what I can’t wrap my head around is, if you can use DR to get to an intersection, why couldn’t you fly direct from an airport to airport back then using DR?

As has been said before in his thread, you have DR on SIDS and STARs, but those were designed by the FAA, so the calculations and obstacle clearances were already determined.
 
Flyingfanatic said:
Back when I got my IFR rating ( pre-GPS) I was taught to go from the airport direct to a VOR to join an airway. (VOR’s being much more plentiful) There was no DR unless it was a SID, that I recall.

Thankfully, GPS has solved this problem.

I guess what I can’t wrap my head around is, if you can use DR to get to an intersection, why couldn’t you fly direct from an airport to airport back then using DR?

As has been said before in his thread, you have DR on SIDS and STARs, but those were designed by the FAA, so the calculations and obstacle clearances were already determined.
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Yeah. Practically speaking, airport to airport isn’t practical. If IFR, and IFR is what the subject here is about, you need some kind of Approach when you get there. So, airport direct to an Approach Fix would be more like it. And that is covered as to obstacle clearances. 91.177 (2)
 
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midlifeflyer said:
Thanks you. Appreciate it.

I guess I mean the difference between "you can" and "you may."

While the regs and guidance may leave some arguable wiggle room, I think (assuming no vectoring) that while Airplane A is permitted to fly IFR Direct BREDY with even a single VOR, airplane B requires some form of approved RNAV capability.
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Hi Mark, I must respectfully disagree.

If one were to zoom out a bit one would find the Stonewall VOR - once you do that you can see that navigating from Mason County to BREDY is a simple matter of using a ruler (or IFR plotter) to draw a line from STV to BREDY, determine the radial by observation and upon departure from T92 intercept and fly that radial until you identify BREDY. It is not a charted route so you are technically DR, but with 1 VOR and a wrist watch you can get there safely and lawfully. You will need to fly the published ODP and confirm your altitude is within the published standard service volume. If that all works out then direct to BREDY is simple.

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Arnold said:
Hi Mark, I must respectfully disagree.

If one were to zoom out a bit one would find the Stonewall VOR - once you do that you can see that navigating from Mason County to BREDY is a simple matter of using a ruler (or IFR plotter) to draw a line from STV to BREDY, determine the radial by observation and upon departure from T92 intercept and fly that radial until you identify BREDY. It is not a charted route so you are technically DR, but with 1 VOR and a wrist watch you can get there safely and lawfully. You will need to fly the published ODP and confirm your altitude is within the published standard service volume. If that all works out then direct to BREDY is simple.
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Taking off from T92 and intercepting a radial from STV VOR to BREDY, whether legal or not, is still not going "direct" to BREDY. It's intercepting a radial to BREDY. It may be close to direct, but that's just a happy coincidence of geometry. Direct means direct - no intercepting anything to get there, no turns, you simply go straight there.
 
RussR said:
Direct means direct - no intercepting anything to get there, no turns, you simply go straight there.
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That's the logic behind Garmin's Direct-To button.
:cheerswine:
 
luvflyin said:
Wasn't that one about to many NDB's on the same frequency or something like that?
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That started it, and at some point, the crew asked if they could go "direct". The controller, not understanding the meaning of "direct", told them they could. (The controller was interviewed for the TV docudrama on the accident, and said something like "to me direct means you will be able to go there without being delayed" and that still needed them to follow the full route in the clearance.)

However, the crew also thought "cleared to [clearance limit]" was a direct-to instruction when it was not. They should have also known there can't be "direct to" clearances out of radar contact.
 
Palmpilot said:
My recollection is that there were duplicate identifiers.
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Yes, but they were essentially pointed towards Cali, not Bogota. The simple procedure of syncing heading then using heading mode should have been step #1; i.e. sitting on your hands until you've got a sound plan.
 
Flyingfanatic said:
Without GPS or radar vectors, can you navigate from an airport to an intersection on a VOR airway or just to the airway itself without first going to a VOR?
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Seems to me the whole purpose of a diverse departure procedure is to allow a departing aircraft to aquire an airway within 25nm (46 mountainous terrain). Further, it seems listing the intersection is a limitation of computer filing technology. Too vague to simply list the airway for ATC's computer brain. But if you fly in Boston Center airspace they won't let you depart IFR without GPS even if the airport is within the lateral limits of the Victor Airway. Certain @someones (you know who you are) on this board will defend that policy by saying it's a long-standing universal one. Well I don't agree, but if it is it shouldn't be, IMO.
 
dtuuri said:
Seems to me the whole purpose of a diverse departure procedure is to allow a departing aircraft to aquire an airway within 25nm (46 mountainous terrain). Further, it seems listing the intersection is a limitation of computer filing technology…
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It is my understanding that a “diverse departure” has been renamed essentially to a “diverse vector area” and the whole purpose of it is to get you to MVA - not an airway per se (even if that’s where you wind up most of the time).
 
Trogdor said:
It is my understanding that a “diverse departure” has been renamed essentially to a “diverse vector area” and the whole purpose of it is to get you to MVA - not an airway per se (even if that’s where you wind up most of the time).
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That's incorrect. The two are separate procedures and serve separate functions. Every airport with an instrument approach is evaluated for a diverse departure, to see if the obstacle and terrain permit it. This allows you to climb and not hit anything if you follow any limitations in the diverse departure, regardless of whether it complies with an ATC clearance or not. It's evaluated to 25 or 46 nm from the airport. Typically there is an airway within that distance, though in some remote areas that may not be true. Radar coverage is not required or considered.

A diverse vector area tells ATC what range of headings they can assign on departure in order to get the airplane to their MVA. It's very much an ATC function, and these are developed in coordination with ATC and consider their radar coverage.

So, you will have a diverse departure (or at least an evaluation of one) at every IFR airport regardless of size or ATC services. You will only have a diverse vector area at larger airports that have the radar coverage to support it (and the need for it - note that none of the NYC airports have a DVA, for example).
 
RussR said:
It's evaluated to 25 or 46 nm from the airport. Typically there is an airway within that distance, though in some remote areas that may not be true.
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And, @Trogdor, if you aren't within an airway within that distance you should be 91.177 compliant for random routes if your climb gradient exceeded the AIM guidance of 200'/nm. Thereafter, though, obstacle avoidance is all on you. To be forewarned is to be forearmed. ;)
 
RussR said:
That's incorrect. The two are separate procedures and serve separate functions. Every airport with an instrument approach is evaluated for a diverse departure, to see if the obstacle and terrain permit it. This allows you to climb and not hit anything if you follow any limitations in the diverse departure, regardless of whether it complies with an ATC clearance or not. It's evaluated to 25 or 46 nm from the airport. Typically there is an airway within that distance, though in some remote areas that may not be true. Radar coverage is not required or considered.

A diverse vector area tells ATC what range of headings they can assign on departure in order to get the airplane to their MVA. It's very much an ATC function, and these are developed in coordination with ATC and consider their radar coverage.

So, you will have a diverse departure (or at least an evaluation of one) at every IFR airport regardless of size or ATC services. You will only have a diverse vector area at larger airports that have the radar coverage to support it (and the need for it - note that none of the NYC airports have a DVA, for example).
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I stand corrected. Yeah, that makes total sense.

@RussR

It seems if there is radar to support it and a need for it “the DD becomes a DVA as opposed to just a DD”, right?
 
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Trogdor said:
I stand corrected. Yeah, that makes total sense.

@RussR

It seems if there is radar to support it and a need for it “the DD becomes a DVA as opposed to just a DD”, right?
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No, they're two separate things. An airport can easily have both.

The complicating factor comes in that DVAs are most often established where terrain or obstacles are a factor. The DVA will tell ATC that they can vector on departure from heading 360 - 150, but NOT 150-360 because there's mountain there. But since there's a mountain there, there may likely not be a diverse departure either - instead, some kind of a departure route will be established. So you'll have both the obstacle departure procedure and the DVA listed in the book. Look at SQL, for example.

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It clearly failed a diverse departure evaluation, but that's a separate issue. So a departure route was established involving the SJC R-281, etc.

And a DVA was established allowing radar vectors. Note that here it just says "headings as assigned by ATC", there is a separate part of the DVA form that ATC gets telling them what range of headings they can assign:

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dtuuri said:
Seems to me the whole purpose of a diverse departure procedure is to allow a departing aircraft to aquire an airway within 25nm (46 mountainous terrain). Further, it seems listing the intersection is a limitation of computer filing technology. Too vague to simply list the airway for ATC's computer brain. But if you fly in Boston Center airspace they won't let you depart IFR without GPS even if the airport is within the lateral limits of the Victor Airway. Certain @someones (you know who you are) on this board will defend that policy by saying it's a long-standing universal one. Well I don't agree, but if it is it shouldn't be, IMO.
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Not sure if I know who I am, but it is a long standing policy from 7110.65Z, 4-1-1 Navaid Use Limitations and 4-1-2 Exceptions. The policy was modified to allow aircraft equipped with GPS as an exception. Senator Thune's office was very helpful in getting the FAA to add the GPS exception. With the new service volumes, it is probably appropriate to update the guidance in 4-1-1 to reflect the possibility of increased SSV.
 
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