Airway nav help- >80mi between VOR

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Tokirbymd

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Tokirbymd
Prepping for IFR checkride- nav route given has segment between BNA and DYR on V140 that is 128 miles between VOR on Lo-Enroute chart. Low altitude VOR service volumes are guaranteed to 40mi. No in-between checkpoints have alternate intersecting VOR radials to use as intermediate point. How can you confirm navigation between those two VOR (assuming GPS is lost) with >80mi distance? Has this specific route been surveyed and the protected corridor expanded wider than 4mi each side?
 
If it's published, it is navigable.

Standard service volumes are for when you are off published routes.
 
You are confusing 2 items. When off airway the VORs must be within 80 nm. On airway you are guaranteed reception provided you are following airway rules. (Altitudes, change over points, ect.)
 
what the others said. The reference is AIM paragraph 1-1-8c. “Standard Service Volume limitations do not apply to published IFR routes or procedures.”
 
BNA is an H VORTAC. It’s good for 100 miles below 14,500, 130 miles up to 45,000 and then 100 again above that. I’ve never heard of exceeding the 8 mile width via ‘survey.’ However Airways widths do exceed 8 miles beyond 51 miles from the VOR. It’s based on plus or minus 4.5 degrees from the airway radial. Basic Service Volumes can be exceeded via ‘survey,’ if that’s the right word. The Frequency Management Office does that. Seeing as how V140 there doesn’t have a Change Over Point, I’m guessing that’s been done.

EDIT: @Tokirbymd , disregard the service volume stuff. It wouldn’t apply to V140 or any airway
AIM 1-1-8 c. Standard Service Volume limitations do not
apply to published IFR routes or procedures.

More EDIT: sheesh @MauleSkinner had already said this. Note to self, read the thread before replying
 
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luvflyin said:
BNA is an H VORTAC. It’s good for 100 miles below 14,500, 130 miles up to 45,000 and then 100 again above that.
Click to expand...

40 nm up to 14500, then 100 nm to 18000. The rest is correct.

AIM Fig 1-1-1.

aim_img_cca.jpeg


Fun fact: These altitudes are above the facility elevation, so AGL not MSL.
 
RussR said:
40 nm up to 14500, then 100 nm to 18000. The rest is correct.

AIM Fig 1-1-1.

aim_img_cca.jpeg


Fun fact: These altitudes are above the facility elevation, so AGL not MSL.
Click to expand...

Thanks. My memory was scrambled, post edited.
 
aterpster said:
And, a few airways have PCG gaps. Doubt there any east of the Rockies.
Click to expand...

PCG?? Is that the same as MEA Gap

EDIT: I found it, I think, Navigational Course Gap. Did you mean NCG or is PCG really a thing?
 
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The theoretical range for a VOR, given a strong-enough signal and ideal conditions (no obstructions or radio/atmospheric interference) is the line-of-sight equation, which is approximately

d = 1.15 * sqrt(h)

where d is the reception distance in nautical miles (use 1.5 instead of 1.15 for statute miles) , and h is your height above the transmitter in feet. So If the VOR is at 2,000 ft MSL and you're flying at 9,000 ft MSL, you're 7,000 ft above the VOR and the furthest you'd reasonably have a faint hope of picking it up in perfect conditions would be

1.15 * sqrt(7,000) =~ 1.15 * 83.67 =~ 96 nm

That's an ideal, though, not necessarily a reality, and not necessarily tested for accuracy by the FAA. In rare cases, the radio beams will bend slightly over the horizon and give you a touch more range.

In my experience, even though DME also follows the line of sight rule, it usually doesn't kick in as early as the VOR signal, and the VOR CDI is pretty wonky at the outside extreme of its range.
 
luvflyin said:
PCG?? Is that the same as MEA Gap

EDIT: I found it, I think, Navigational Course Gap. Did you mean NCG or is PCG really a thing?
Click to expand...
Used in procedure design all the time.A2_82603B.jpg
 
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