Can I fly off center on a Victor airway?

flyzone

flyzone

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Flyzone
I am a new IFR pilot flying a single engine Piper with steam gauges (ILS, VOR, DME) and no IFR GPS. I plan a trip from the northeast to Florida via V1. Below TYBEE the airway gets a bit distant from the shoreline and I prefer to be closer to the shoreline for safety. I know I can fly a bit inland on another airway but the shoreline route is much more interesting and keeps me awake :)

Can I fly a few miles right of course (say, 3) to nudge the shoreline without causing grief for anybody? I know the airway is 4 miles on each side of the center line so it seems that technically it would be ok. Is there any rule about flying the center line if you are able?
 
Should be no issue at all. If you want to fly more than 4 miles off center just ask ATC
 
A controller once asked me to fly on the center line of an airway. Apparently he was unaware that VOR receivers are allowed to be off by as much as four or six degrees (depending on how they're checked). My CDI said I was already on the center line, so I offset the OBS a little to make him happy.
 
Airways are 4nm from either side for obstacle clearance purposes. ATC still expects you to fly down the center of it. If you want to deviate from the clearance, tell ATC what you want to do. Just be prepared to hold, change altitude, vectored, etc. if ATC cannot accommodate. Always have a plan B (and C and D for that matter).
 
Palmpilot said:
A controller once asked me to fly on the center line of an airway. Apparently he was unaware that VOR receivers are allowed to be off by as much as four or six degrees (depending on how they're checked). My CDI said I was already on the center line, so I offset the OBS a little to make him happy.
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Controllers these days are spoiled by GPS, which puts everybody smack dab on the centerline (for better or worse).
 
V1 CHS SAV V37 CRG Keeps you over land and you can see plenty of shore line.

I filed and flew that instead of over water from Jupiter FL. I would have flown it heading south but wx pushed me inland from Virginia well into Georgia.
 
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When you get to the Savanah area ,the controllers like you to stay on the airway.
 
Part 91.181:

§91.181 Course to be flown.
Unless otherwise authorized by ATC, no person may operate an aircraft within controlled airspace under IFR except as follows:

(a) On an ATS route, along the centerline of that airway.

(b) On any other route, along the direct course between the navigational aids or fixes defining that route. However, this section does not prohibit maneuvering the aircraft to pass well clear of other air traffic or the maneuvering of the aircraft in VFR conditions to clear the intended flight path both before and during climb or descent.
 
Thanks for the responses. I guess, like almost always, the answer is "just ask". But newbies like me don't want to ask stupid questions (if we can avoid it) :)
 
aterpster said:
Part 91.181:

§91.181 Course to be flown.
Unless otherwise authorized by ATC, no person may operate an aircraft within controlled airspace under IFR except as follows:

(a) On an ATS route, along the centerline of that airway.

(b) On any other route, along the direct course between the navigational aids or fixes defining that route. However, this section does not prohibit maneuvering the aircraft to pass well clear of other air traffic or the maneuvering of the aircraft in VFR conditions to clear the intended flight path both before and during climb or descent.
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Well, that pretty much explains it. Thanks. On the centerline unless you are maneuvering for traffic, etc.

As metioned by Palmpilot above, I have had the experience of the VOR being centered but still off course by a considerable amount (i.e. miles). I later checked the AFD and found that the VOR had more unusable radials than good ones. The controller I was working with didn't seem to know this nor did I. I think you are more likely to encounter this off airways and when filing direct since that makes radial selection a crap shoot but it is becoming more of a factor for those of us still fiying steam guages as this equipment ages. My tablet helps but I don't want to rely on that since it has been known to lose its signal.

Now if I can only find $15K for an IFR GPS.
 
flyzone said:
See my comment on non-airway radials.
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Shouldn't be a reception problem if you're high enough and using the higher power VORs. Is that what you mean? When you file VOR to VOR that gives you a little more latitude, ie vs controller watching to make sure you're on that centerline if on an airway.
 
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flyzone said:
Can I fly a few miles right of course (say, 3) to nudge the shoreline without causing grief for anybody?
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Maybe, but why risk causing grief for anybody? Just ask to follow the shoreline.

I know the airway is 4 miles on each side of the center line so it seems that technically it would be ok. Is there any rule about flying the center line if you are able?
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Yes, FAR 91.181(a):

§91.181 Course to be flown.

Unless otherwise authorized by ATC, no person may operate an aircraft within controlled airspace under IFR except as follows:

(a) On an ATS route, along the centerline of that airway.

(b) On any other route, along the direct course between the navigational aids or fixes defining that route. However, this section does not prohibit maneuvering the aircraft to pass well clear of other air traffic or the maneuvering of the aircraft in VFR conditions to clear the intended flight path both before and during climb or descent.


Note that airways are not always four miles on each side of the centerline. Airways accommodate a 4.5 degree splay. At 51 miles from the VOR that splay exceeds four miles and the airway expands accordingly. Within 38 miles of the VOR the width can be reduced to three miles if needed to clear another procedure.
 
flyzone said:
Thanks for the responses. I guess, like almost always, the answer is "just ask". But newbies like me don't want to ask stupid questions (if we can avoid it) :)
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Unlike many others, I believe there is such a thing as a stupid question*, although one asked in these forums rarely qualifies.

Asking ATC for a deviation for just about any reason is not (never?) a stupid question. It is a sign of being pilot in command.

[* Real question by a defendant cross-examining the victim in a criminal assault case: "How could you identify me ? Your back was turned when I hit you!"]
 
flyzone said:
As metioned by Palmpilot above, I have had the experience of the VOR being centered but still off course by a considerable amount (i.e. miles). I later checked the AFD and found that the VOR had more unusable radials than good ones. The controller I was working with didn't seem to know this nor did I. I think you are more likely to encounter this off airways and when filing direct since that makes radial selection a crap shoot but it is becoming more of a factor for those of us still fiying steam guages as this equipment ages. My tablet helps but I don't want to rely on that since it has been known to lose its signal.
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Other than a charted MEA gap you should never encounter a known unusable radial on airways.
 
Why not just cancel IFR when you get closer to the shore line weather permitting? You are supposed to fly on the centerline of an airway.
 
roncachamp said:
Note that airways are not always four miles on each side of the centerline. Airways accommodate a 4.5 degree splay. At 51 miles from the VOR that splay exceeds four miles and the airway expands accordingly. Within 38 miles of the VOR the width can be reduced to three miles if needed to clear another procedure.
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Is it correct that reduction to 3 miles can only be done where there is good ATC radar coverage and within 40 miles of the radar antenna? Seems like the 3 mile value implies that.
 
mscard88 said:
Shouldn't be a reception problem if you're high enough and using the higher power VORs. Is that what you mean? When you file VOR to VOR that gives you a little more latitude, ie controller watching to make sure you're on that centerline if on an airway.
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Apparently many of these radials are unusable even at higher altitudes. For example check out Modena (MXE) at my nearby airport with many unusable radials above 6K ft. There aren't any mountains nearby.
http://aeronav.faa.gov/afd/04feb2016/ne_278_04FEB2016.pdf
 
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aterpster said:
Is it correct that reduction to 3 miles can only be done where there is good ATC radar coverage and within 40 miles of the radar antenna? Seems like the 3 mile value implies that.
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Radar is not a factor. The three mile distance comes from the same 4.5 degree splay that pushes airway width beyond four miles at 51 miles from the VOR; at 38 miles from the VOR the splay is three miles. The bulge at 51 miles could be seen on charts where the airspace beyond the airway lateral limits was uncontrolled. I use the past tense because I can't find any examples in the US anymore. Airway width reductions were not charted. For more information see FAA Orders 7400.2K Procedures for Handling Airspace Matters, paragraph 20-3-3, and 8260.19G Flight Procedures and Airspace, paragraph 3-2-2.

4 miles.jpg 3 miles.jpg
 
jordane93 said:
Why not just cancel IFR when you get closer to the shore line weather permitting? You are supposed to fly on the centerline of an airway.
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Weather permitting is the rub. If not now than later in the flight.
frfly172 said:
When you get to the Savanah area ,the controllers like you to stay on the airway.
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My little bit of experience has been that they give me a deviation away or around Savannah and Charleston. The last time the controller thanked me for helping him out having routed me direct to TYBEE from SSI (going north). That isn't too bad for me since you mostly follow the shoreline just a mile or two off shore. Further than that and my knees knock.
 
You're actually encouraged not to be on centerline (if you don't want to be) on a NAT track. (Grin...)
 
aterpster said:
Much of that can be attributed to aging VOR stations and limited maintenance.
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I understand that trees, buildings and other low obstacles just beyond the perimeter of the VOR site can clobber some radials. However, I can't explain why you would lose so many at higher altitudes. Maintenance, perhaps,but are parts that hard to find? I understand that 50% of the VORs will remain in use for the foreseeable future but I think they want to close this one down. I guess they will -- a radial at a time.
 
What I've heard on many of the VORs that have a bunch of radials marked unusable these days, that didn't in the past, is that certification and flight test and the capabilities of the flight test gear, got better about recognizing multi path effects on the reception of the station.

Often triggered by new physical obstacles around it.

The extreme example of this sort of "bounce" would be when I work some front range stations on 10 GHz, we are both far better off to point the dishes or Yagis west toward Pikes Peak or Mt Evans to talk on SSB, than directly at each other because terrain is in the way.

VOR signals at VHF are similarly affected but not as much.

When you're high up in an aircraft, natural reflections are going to arrive at your receiver slightly slower and somewhat weaker. The usual effect you see on the real instrument is a "wavering" needle.

The flight check aircraft, as the rumor I've heard goes, have better test gear that can see this better these days and the radial doesn't pass spec.

The station's themselves are pretty simple. There's not that much to them. I suspect the maintenance issues mostly lie around finding parts and too many techs out playing ADS-B instead. I could ask my buddy who does that sort of work. He spent weeks in and out of Trinidad last year fixing something, and I suspect it wasn't a VOR. But he specializes in radar I think.

I still don't know why they didn't just build a wide area multilaterization solution. Simple vertical antennas. Simple maintenance.

Well actually I do know why. No identification data. ADS-B isn't about just seeing aircraft. They want to know which specific aircraft. There's a subtle but important difference there.
 
denverpilot said:
...Well actually I do know why. No identification data. ADS-B isn't about just seeing aircraft. They want to know which specific aircraft. There's a subtle but important difference there.
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Big Brother?
 
roncachamp said:
Radar is not a factor. The three mile distance comes from the same 4.5 degree splay that pushes airway width beyond four miles at 51 miles from the VOR; at 38 miles from the VOR the splay is three miles. The bulge at 51 miles could be seen on charts where the airspace beyond the airway lateral limits was uncontrolled. I use the past tense because I can't find any examples in the US anymore. Airway width reductions were not charted. For more information see FAA Orders 7400.2K Procedures for Handling Airspace Matters, paragraph 20-3-3, and 8260.19G Flight Procedures and Airspace, paragraph 3-2-2.
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Thanks.

Those Part 71 51 mile bulges are gone because most of the Class G airspace above 1,200 agl in the continental U.S. has been rule-made out of existence in the past 5, or so, years. The bulges are still in Part 95, but those aren't charted.
 
aterpster said:
Those Part 71 51 mile bulges are gone because most of the Class G airspace above 1,200 agl in the continental U.S. has been rule-made out of existence in the past 5, or so, years.
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Yes, that's why examples can't be found.

The bulges are still in Part 95, but those aren't charted.
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They're on controller charts, and on Position Display Maps derived from them. Here's a PDM with several examples:

PDM jpeg.jpg
 
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