The A2A Simulations Community

"Come share your passion for flight"
It is currently Fri Sep 21, 2018 9:48 am

All times are UTC - 5 hours




Post new topic Reply to topic  [ 14 posts ] 
Author Message
 Post subject: SEY VOR
PostPosted: Sun Aug 14, 2016 5:58 am 
Offline
Airman

Joined: Tue Jun 14, 2016 10:17 am
Posts: 24
I'm trying to interpret the following: 1.VOR/DME UNUSBL 245-250 BYD 20 NM BELOW 3500 FT.

I think it means that the VOR/DME is unusable below 3500' under the condition 245-250 BYD 20 NM. What does that condition mean?


Top
 Profile  
 
 Post subject: Re: SEY VOR
PostPosted: Sun Aug 14, 2016 6:02 am 
Offline
A2A Captain
User avatar

Joined: Fri Jun 06, 2014 1:06 pm
Posts: 7010
Location: United Kingdom
Jim,

I'm guessing it means that it's only the radials 245-250 which are unusable beyond 20 nautical miles and (or should that be or) below 3,500 feet. Presumably this would be a result of terrain masking or something similar.

I'll leave it to the proper pilots to confirm though! :wink:

Nick


Top
 Profile  
 
 Post subject: Re: SEY VOR
PostPosted: Sun Aug 14, 2016 6:26 am 
Offline
A2A Mechanic
User avatar

Joined: Sun May 26, 2013 5:03 am
Posts: 3846
Not a proper pilot here, but that how it read unless I totally misinterpret it! (Beyond 20 nm when below 3500 ft on that given direction from the station.)

I don't recall where the criteria for aerial navigation aids were laid out for FAA, but certain other source provided the info that combined ground station error and site effect error must be less than ±3°, and "scalloping" amplitude, where observed, must be less than ±2°. It is likely, that in this case, these requirements (or jurisdiction's equivalents) or some others are not met by the station in question, or it is masked altogether. One often finds these limitations with localizers (while their working principle is of course a little different) but with VORs they seem to be relatively rare, as the signal is modestly robust for an analog one.

-Esa

_________________
I shall bear the entire responsibility for my actions and shall in no way discharge them on another.


Top
 Profile  
 
 Post subject: Re: SEY VOR
PostPosted: Sun Aug 14, 2016 11:08 am 
Offline
Technical Sergeant
User avatar

Joined: Tue Jul 03, 2012 12:46 am
Posts: 685
Location: California
The restrictions are common for VORs, especially in mountainous areas or city areas where the lower level portion of the signal can be distorted, blocked, or otherwise attenuated. Here are a few examples with the restrictions you cite:
Cleveland OH http://www.airnav.com/cgi-bin/navaid-info?DJB
Missoula MT http://www.airnav.com/cgi-bin/navaid-info?id=MSO
St. Louis MO http://www.fltplan.com/nav/CSX.htm

Always check any VOR you will use for these kind of things that might affect your flight.
Also be aware their are high level and low level VORs and VORs with varying ranges, etc.


Top
 Profile  
 
 Post subject: Re: SEY VOR
PostPosted: Sun Aug 14, 2016 12:10 pm 
Offline
A2A Mechanic
User avatar

Joined: Sun May 26, 2013 5:03 am
Posts: 3846
Ah yes, in mountainous areas these are most certainly more common issues. For sake of it, I checked the neighbors with some bumps, Sweden [PDF] and Norway [PDF] where there are a couple of navigational aids that are remarked with "known issues".

In the sim I don't bother checking them as they are all "perfect" anyway, albeit some kind of rudimentary terrain masking appears to be modeled. Also, they won't go down in the sim even if there was a NOTAM in reality. Obviously, a true hardcore simmer would kill them by hand for each flight if they happen to be down in reality! :D

It would be cool, btw, if these errors were "simulatable" but perhaps not these days yet.

-Esa

_________________
I shall bear the entire responsibility for my actions and shall in no way discharge them on another.


Top
 Profile  
 
 Post subject: Re: SEY VOR
PostPosted: Wed Aug 17, 2016 11:31 pm 
Offline
Technical Sergeant
User avatar

Joined: Tue Jul 03, 2012 12:46 am
Posts: 685
Location: California
AKar wrote:
Obviously, a true hardcore simmer would kill them by hand for each flight if they happen to be down in reality! :D


I laughed very hard when I read your statement. That would be a true hardcore simmer! Thanks for the laugh!


Top
 Profile  
 
 Post subject: Re: SEY VOR
PostPosted: Tue Aug 23, 2016 6:17 pm 
Offline
Senior Airman

Joined: Sat Dec 13, 2014 11:38 am
Posts: 217
Location: Vancouver, BC
FSX does seem to have the range functionality, which is 1.23 times the square root of the altitude difference in feet, built in. There is also a service range defined for each station about signal power. I don't recall much more than that. In practice I have picked up a VOR signal much further than I should have, but the needle can jump all over the place, even when close. The GPS is much more stable.

They occasionally shut them off for odd reasons, and sometimes will NOTAM out sectors for construction related or building related things. Some victor airways get closed (if using the VOR that is) due to service hassle for a while, or unreliable reception, or just out of spec beacons (due to not having been tested recently, not due to actually being no good.)

_________________
Clear Direct


Top
 Profile  
 
 Post subject: Re: SEY VOR
PostPosted: Sat Aug 27, 2016 6:13 am 
Offline
Staff Sergeant

Joined: Tue Feb 01, 2005 8:13 am
Posts: 352
Having written a few such NOTAMs, I agree with the previous interpretation.

Some NOTAM writers do seem to go out of their way to save single letters, sometimes to the point of potential for confusion. Omitting the 'R' designating radials as radials would qualify IMO. Without an 'R', it is supposed to be a a heading/bearing, so in this case we just do not know what to make of it. I've seen national chart publishers do the same thing...

The governing documents outside of the FAA pond would be ICAO Annex 10 Vol I, 'Radio Navigation Aids' and then Doc 8071 as the go-to on how to verify the functionality through flight inspection (and when to publish restrictions).

BTW, the range formula coefficient got updated to 1.25 recently, to better depict the wave propagation over the horizon. That admittedly only really matters if you are to take a test on it. :)

In real life, the differences in functionality between various VORs can be very apparent. Especially C-VORs can be... interesting. If you are on published procedures, you are OK (unless NOTAMed, of course) but if you try to use the systems to support your navigation outside of that, you need to be aware of the service volumes and any restrictions.

Cheers,
/Fred

_________________
Be warned: Aero engineer, real life pilot, sim programmer. Nothing good can come out of that.


Top
 Profile  
 
 Post subject: Re: SEY VOR
PostPosted: Sat Aug 27, 2016 12:10 pm 
Offline
A2A Test Pilot
User avatar

Joined: Sat Feb 16, 2008 3:49 pm
Posts: 2054
Location: KUMP
ft wrote:
Some NOTAM writers do seem to go out of their way to save single letters, sometimes to the point of potential for confusion.

Yeah it's another language. Sometimes I go for the "plain text" if it is available.

ft wrote:
Omitting the 'R' designating radials as radials would qualify IMO. Without an 'R', it is supposed to be a a heading/bearing, so in this case we just do not know what to make of it. I've seen national chart publishers do the same thing...

For the U.S. it is defined by radials.

SEY seems like an odd one because that "unuse-ability" is over water. Must be something wrong (who knows what) when it was Flight Checked (AINonline FAA Flight Check operations).

Normally I see these Unusable Ranges in the Chart Supplements aka the Airport/Facility Directory. The Brickyard VOR (VHP) is a bit interesting to me as the A/FD lists the TACAN unusable: 312º–346º byd 25 NM blo 4,000. But if you look at Victor 24, it is defined by the VHP 311º and usable to at least JAKKS which is 31DME - the MEA is only 2700'. Northwest-bound you would want to be at 4000' for the MRA at POTES intersection. One reason why it is nice to use Enroute Charts for planning if VOR hopping. (Definitions of the MEA / MRA in an AVweb article All Those Ms.)

_________________
Rob Osborne
Flight Instructor - CFI, CFII, MEI, MEII
A & P Mechanic


FAASTeam - Safer Skies Through Education
Professionalism in aviation is the pursuit of excellence through discipline, ethical behavior and continuous improvement. NBAA


Top
 Profile  
 
 Post subject: Re: SEY VOR
PostPosted: Sat Aug 27, 2016 1:48 pm 
Offline
Staff Sergeant

Joined: Tue Feb 01, 2005 8:13 am
Posts: 352
The point is that the format ddd° should be used for bearings/headings. Radials are not in degrees, and should be prefixed by an R, in order to distinguish the two concepts.

Technically, 312°-348° indicates a sector given by bearings, regardless of the radials contained in that sector. For a VOR, using radials usually makes more sense.

What they actually mean in these instances, well... if it was crucial to my operation, I'd ask for clarification before assuming anything.

As for the Brickyard entry, that should only be the TACAN part so the VOR should be just fine.

SEY has a hill in the direction with limitations. After looking at it in GE, I'm not surprised that they're not getting full coverage. If I'd been doing the commissioning flight check, I'd have been expecting to see something just from looking at the site.

Edit: Nice writeup in the linked article!

_________________
Be warned: Aero engineer, real life pilot, sim programmer. Nothing good can come out of that.


Top
 Profile  
 
 Post subject: Re: SEY VOR
PostPosted: Sat Aug 27, 2016 2:41 pm 
Offline
A2A Test Pilot
User avatar

Joined: Sat Feb 16, 2008 3:49 pm
Posts: 2054
Location: KUMP
ft wrote:
The point is that the format ddd° should be used for bearings/headings. Radials are not in degrees, and should be prefixed by an R, in order to distinguish the two concepts.

I don't know, Fred. I'm just explaining how the FAA does it. They are defined by radials in terms of degrees. Fwiw, both Victor Airways and Intersections are defined by radials. And why would a radial not be in degrees? Here in the U.S. that is how I see them defined. :?

ft wrote:
Technically, 312°-348° indicates a sector given by bearings,

In the UK?

ft wrote:
As for the Brickyard entry, that should only be the TACAN part so the VOR should be just fine.

Good point... that very well could be. I think of TACAN equating to VORTAC (which not necessarily so)... good to check as you say, when calling Flight Service for a briefing.

_________________
Rob Osborne
Flight Instructor - CFI, CFII, MEI, MEII
A & P Mechanic


FAASTeam - Safer Skies Through Education
Professionalism in aviation is the pursuit of excellence through discipline, ethical behavior and continuous improvement. NBAA


Top
 Profile  
 
 Post subject: Re: SEY VOR
PostPosted: Sun Aug 28, 2016 9:22 am 
Offline
A2A Aviation Consultant
User avatar

Joined: Mon Mar 03, 2008 12:06 pm
Posts: 2096
Location: Wichita Falls, Texas, USA
ft wrote:
The point is that the format ddd° should be used for bearings/headings. Radials are not in degrees, and should be prefixed by an R, in order to distinguish the two concepts.


The point is, it doesn't matter what you think it should or shouldn't be. The FAA has a format for NOTAMs and Notices and they adhere to it. That format says that whenever a VOR is used to describe a fix or area, it will state RADIAL and DME. Whenever an NDB or other fix (such as an airport) is used, BEARING and DISTANCE will be used. There is no need for a prefix or other clarification. The format is the same one used by the ICAO so I'm not sure where the confusion is. In fact, looking at the AIP for multiple countries in Europe, the only one that uses the "R" prefix is the UK. The relevant document is the AIP for the given country, then the Enroute portion, and Section 4.1. If you have a Eurocontrol login, it's under the PAMS Light application, then select the country, AIP, ENR, and then scroll down to ENR 4.1.

_________________
Image


Top
 Profile  
 
 Post subject: Re: SEY VOR
PostPosted: Tue Aug 30, 2016 1:57 pm 
Offline
Senior Airman

Joined: Sat Dec 13, 2014 11:38 am
Posts: 217
Location: Vancouver, BC
Changing reception range formulae? Good grief, the world is coming apart. Kids these days. Get off my lawn!

_________________
Clear Direct


Top
 Profile  
 
 Post subject: Re: SEY VOR
PostPosted: Thu Sep 01, 2016 1:48 pm 
Offline
A2A Mechanic
User avatar

Joined: Sun May 26, 2013 5:03 am
Posts: 3846
William Hughes wrote:
Changing reception range formulae? Good grief, the world is coming apart. Kids these days. Get off my lawn!
:mrgreen:

Someone must have felt important when filing the change! :D

-Esa

_________________
I shall bear the entire responsibility for my actions and shall in no way discharge them on another.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 14 posts ] 

All times are UTC - 5 hours


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group