Use of Lat/Longs in IFR flight plans

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Jeffreyac

Filing Flight Plan
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Jeffreyac
Hi all,

Got into a discussion yesterday about the use of lat/longs for fixes when filing an IFR flight plan. I seem to remember that, while a radial/DME or fix name is MUCH preferred, it is also possible to identify a point using a lat/long on your flight plan in a radar environment.

The regs seem a little vague on the subject - I found a reference stating this was acceptable for RNAV aircraft filing great circle routes above FL390, but I really thought this was acceptable in other situations as well.

So, after a breif regs search - I caved and used the message boards. :rolleyes:

Can anyone confirm or deny if it is legal to define a point on an FAA flightplan using lat/longs? (I mean legal, here. I know it's not a good idea, if you have another way of identifying a fix, and I know why it's not a good idea - I'm just wondering if it is in fact legal to do so on a typical flight...)

Thanks!
Jeff

edit: the reference I've found so far is section 5-1-7, dealing with flight plans. i'm almost certain there is another reference I'm missing, though....
 
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You sure can file that way, but likely you'll hear, "Change of routing -- advise ready to copy..." once airborne (if you don't get a re-route when you get cleared).
 
Jeffreyac said:
Hi all,

Got into a discussion yesterday about the use of lat/longs for fixes when filing an IFR flight plan. I seem to remember that, while a radial/DME or fix name is MUCH preferred, it is also possible to identify a point using a lat/long on your flight plan in a radar environment.

The regs seem a little vague on the subject - I found a reference stating this was acceptable for RNAV aircraft filing great circle routes above FL390, but I really thought this was acceptable in other situations as well.

So, after a breif regs search - I caved and used the message boards. :rolleyes:

Can anyone confirm or deny if it is legal to define a point on an FAA flightplan using lat/longs? (I mean legal, here. I know it's not a good idea, if you have another way of identifying a fix, and I know why it's not a good idea - I'm just wondering if it is in fact legal to do so on a typical flight...)

Thanks!
Jeff

edit: the reference I've found so far is section 5-1-7, dealing with flight plans. i'm almost certain there is another reference I'm missing, though....
Click to expand...

Perfectly legal, the regs say only "the proposed route", there's no prohibition on the filing of coordinates.
 
dmccormack said:
You sure can file that way, but likely you'll hear, "Change of routing -- advise ready to copy..." once airborne (if you don't get a re-route when you get cleared).
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Possibly, but if the route is unacceptable it wont be because lat/longs were used. Lat/longs have an advantage over radial/DME because the computer will always recognize latitude and longitude. A radial and distance from an unknown VORTAC will be rejected.
 
roncachamp said:
Possibly, but if the route is unacceptable it wont be because lat/longs were used. Lat/longs have an advantage over radial/DME because the computer will always recognize latitude and longitude. A radial and distance from an unknown VORTAC will be rejected.
Click to expand...

The OP is flying in NJ. My guess is there are preferred routes from/to everywhere... no?
 
It's been a while but I've filed computer generated plans (/G) and gotten lat/lon fixes in my clearance. Only after entering them into the GPS did I discover "as filed" would have worked also.

Joe
 
dmccormack said:
The OP is flying in NJ. My guess is there are preferred routes from/to everywhere... no?
Click to expand...

No, not to everywhere. He may be departing from an airport where preferential departure routes apply, but there are many, many possible destinations that have no preferred arrival routes.
 
roncachamp said:
No, not to everywhere. He may be departing from an airport where preferential departure routes apply, but there are many, many possible destinations that have no preferred arrival routes.
Click to expand...

Well, there are published "IFR Preferred Routes" and then there are in-the-system, not-available-to-us preferences.
 
Thanks for all the replies.

If you're curious, we were still was searching for a reference, so we decided to break the tie by calling up the local FSDO office for guidance. The official word from on high was that filing a flight plan using lat/longs to identify the points was legal and acceptable (though, interestingly enough, they didn't have a reference for where that was written off hand, either, so I feel a little better about not being able to find it!) Anyway, thanks again for the help!

Now i've looked at the regs myself and I'm once more doubtful. There is clearly a section on Area Navigation that specifies that points must be filed as degree-distance fixes from appropriate ground based navaids, and there is a section allowing for the use of lat long in filing above FL390, but nothing on routine usage. After reading the regs, I'm forced to conclude that, despite what I thought, it isn't really legal to file this way... I've got another email pending from the FSDO office; there's probably something I've missed somewhere...
 
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dmccormack said:
The OP is flying in NJ. My guess is there are preferred routes from/to everywhere... no?
Click to expand...
Sort of. Unless you're going to the next airport over, if you're flying in the Richmond-WashDC-Balto-Philly-NY-Providence-Boston corridor, you'll be given a routing which joins a TEC route going in your general direction and follows it to a point near your destination. Filing direct is pretty much a waste of time unless it's 0230 local.
 
Jeffreyac said:
Thanks for all the replies.

It's a little bit of a long story, but the reason I asked was not so much for my personal flying (I'd just file radial/DME fixes!) but that I'm involved with a group looking at the effects/issues with flying unmanned vehicles in the National Airspace System, and one of the discussions thast came up was on filing flight plans (UAV's can't really file or fly to radial/DME fixes, as they don't have that sort of instrumentation, so they do everything by lat/long...) I was pretty certain that this was legal even today, but had another member of the group who remembered differently - and I couldnt find the regs to decide for certain.

So, anyway, it's not so much a question of preferred routing here in NJ, or even operating in the NAS as it stands anywhere today (which, as I'm sure you all know, UAV's can't do today unrestricted for a great many reasons) but just as more of a hypothetical or research issue.

EDIT: If you're curious, we were still was searching for a reference, so we decided to break the tie by calling up the local FSDO office for guidance. The official word from on high was that filing a flight plan using lat/longs to identify the points was legal and acceptable (though, interestingly enough, they didn't have a reference for where that was written off hand, either, so I feel a little better about not being able to find it!) Anyway, thanks again for the help!

EDIT (again!) Now i've looked at the regs myself and I'm once more doubtful. There is clearly a section on Area Navigation that specifies that points must be filed as degree-distance fixes from appropriate ground based navaids, and there is a section allowing for the use of lat long in filing above FL390, but nothing on routine usage. After reading the regs, I'm forced to conclude that, despite what I thought, it isn't really legal to file this way... I've got another email pending from the FSDO office; there's probably something I've missed somewhere...
Click to expand...
UAV's could have a database with the coordinates for pretty much any FIX you'd ever need to file - really a minor technical issue.
 
Areeda said:
It's been a while but I've filed computer generated plans (/G) and gotten lat/lon fixes in my clearance. Only after entering them into the GPS did I discover "as filed" would have worked also.
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I have too. It seemed that when this would happen it was usually because I had filed to an intersection in another center's airspace. Now that you mention it I can't recall that it's happened to me recently.
 
We use ARINC for our flight plans. For a short time span they decided that you needed a fix every 100nm in your routing. If there wasn't a fix nearby to go to, they inserted lat/long waypoints. Incredibly annoying when it comes time to build the flight plan in the FMS and there are 10 to 15 lat/long waypoints in it, and even more annoying when ATC says 'cleared direct to lat/long whatever'. The FMS codes them all, so you'll have LAT01, LAT02, LAT03 etc so when ATC gives a lat/long it's not the easiest thing to figure out which one it is in the flight plan. Enough complaints to ARINC eliminated the practice though. :)
 
I remember plugging a whole bible full of lat/longs on our KBAD-PGUA flight plan a couple years back. Works fine. Of course there are preferred routes over the pacific, alas they were not great circle routes. 496 WX doesn't work over the Pacific either :( Had to rely on the green blob screen downstairs and the overtly optimistic mainland WX shop. "Airman, I think that's a typhoon over in the big satellite...." "Nah sir, that'll die off by the time you're over wake island, sarge's says you're good to go" :rolleyes:

Lat/long Legal? yes. Painful? You betcha.
 
Legal, maybe, but you're NOT supposed to file Lat/Lng below 39,000', according to the AIM. Don Brown has written a good article on this.

If you don't file for FL390 or above you have no business putting Lat/Longs in your flight plan for a flight in the Lower 48 of the good old U.S. of A.
Click to expand...

-Felix
 
Jeffreyac said:
Thanks for all the replies.

If you're curious, we were still was searching for a reference, so we decided to break the tie by calling up the local FSDO office for guidance. The official word from on high was that filing a flight plan using lat/longs to identify the points was legal and acceptable (though, interestingly enough, they didn't have a reference for where that was written off hand, either, so I feel a little better about not being able to find it!) Anyway, thanks again for the help!

Now i've looked at the regs myself and I'm once more doubtful. There is clearly a section on Area Navigation that specifies that points must be filed as degree-distance fixes from appropriate ground based navaids, and there is a section allowing for the use of lat long in filing above FL390, but nothing on routine usage. After reading the regs, I'm forced to conclude that, despite what I thought, it isn't really legal to file this way... I've got another email pending from the FSDO office; there's probably something I've missed somewhere...
Click to expand...

Don't fall into the trap of thinking that the FSDO is always right...you can find differences of opinion between ops inspectors within any FSDO. The only thing you can hang your hat on is an opinion from the Office of the General Counsel.

Bob Gardner
 
sba55 said:
5-1-8 d. 3.
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It says "Pilots of aircraft equipped with latitude/longitude coordinate navigation capability, independent of VOR/TACAN references, may file for random RNAV routes at and above FL 390 within the conterminous U.S. using the following procedures." That's correct, it's also correct below FL 390. but it doesn't say you're not supposed to file Lat/Lng below 39,000'.

​
​
And I didn't say there was something wrong with filing them.
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No, you didn't, Don Brown did. He's wrong.​
 
roncachamp said:
It says "Pilots of aircraft equipped with latitude/longitude coordinate navigation capability, independent of VOR/TACAN references, may file for random RNAV routes at and above FL 390 within the conterminous U.S. using the following procedures." That's correct, it's also correct below FL 390. but it doesn't say you're not supposed to file Lat/Lng below 39,000'.
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No, not specifically. However, since that section is all about specifying what you can do, rather than what you shouldn't do, it stands to reason that filing below 30,000' is not something you're supposed to do. Otherwise - if it applied everywhere - there certainly wasn't a point in talking about 39,000' at all.
roncachamp said:
No, you didn't, Don Brown did. He's wrong.
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It's a matter of opinion. I don't think you can say that he's wrong seeing as though there's nothing factually wrong with his statement and his reasoning is sound. I tend to agree with him, but YMMV.

-Felix
 
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