Don Brown and lat-long

I know Don Brown. He is a good 'ol country boy, and an entertaining writer, but he is not a pilot. His aviation world is circumscribed by the AIM and Air Traffic Control Handbook, with no latitude (no pun intended) allowed. His Avweb column about filing IFR is almost perfect, but there are airplane-owning controllers around the country who will tell you that host computers throughout the system recognize lat-longs, while a radial-distance from a VORTAC several hundred miles away might get bounced because the VORTAC is not in the host computer. Keep filing lat-longs where appropriate even if you never get up to FL390.

Bob Gardner

Oh the shame! :-)

One of Don's problems with L/L's is that by themselves they don't tell the controller diddly about which direction you will be headed. They are just a jumble of numbers on a flight progress strip to a busy ATCS. Secondly, because they don't tell the controller diddly about which direction you will be headed, the controller has no way of verifying that they are correctly filed by you, DUATS or FSS until after you get radar identified. One digit of mistake on the filer's part can cause mountians of headaches for ATC with both IFR separation requirements and just plain old inter-ATC coordination fumbles. And speaking of radar identified, what happens if you *don't* get radar identified...?

File Lat/ longs at your pleasure, but don't be surprised at the results. Down here in ATC-land, we'll probably be surprised for you...

Chip, ZTL
"Bob Gardner" wrote in message et...
I know Don Brown. He is a good 'ol country boy, and an entertaining writer, but he is not a pilot. His aviation world is circumscribed by the AIM and Air Traffic Control Handbook, with no latitude (no pun intended) allowed. His Avweb column about filing IFR is almost perfect, but there are airplane-owning controllers around the country who will tell you that host computers throughout the system recognize lat-longs, while a radial-distance from a VORTAC several hundred miles away might get bounced because the VORTAC is not in the host computer. Keep filing lat-longs where appropriate even if you never get up to FL390.

Bob Gardner

Chip Jones wrote:
: File Lat/ longs at your pleasure, but don't be surprised at the results.
Down here in ATC-land, we'll probably be surprised for you...

After reading a bunch of Don's articles, perhaps a reasonable
compromise would be comments describing what the L/L is for? I,
personally, prefer using prominent navaid radial/distance for defining an
RNAV (or unknown identifier) rather than L/L anyway. I don't think in
terms of L/L (and my VFR GPS isn't quite as approved as the DME/VOR RNAV).

YMMV
-Cory

--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

wrote in message
...

After reading a bunch of Don's articles, perhaps a reasonable
compromise would be comments describing what the L/L is for? I,
personally, prefer using prominent navaid radial/distance for defining an
RNAV (or unknown identifier) rather than L/L anyway. I don't think in
terms of L/L (and my VFR GPS isn't quite as approved as the DME/VOR RNAV).


The problem with navaid radial/distance is that it relies on the navaid
location being known to the flight data processing computer. If the
computer doesn't recognize the base fix it won't process it. The one fix
format that always works is latitude/longitude.

"Steven P. McNicoll" wrote in message link.net...

The problem with navaid radial/distance is that it relies on the navaid
location being known to the flight data processing computer. If the
computer doesn't recognize the base fix it won't process it.

Steve,

How does the flight data processing computer handle direct VOR
routing between VORs it doesn't recognize? Does it barf on that
too, or is this barfing specific to VOR radial-distance?

Thanks
Sydney

(Snowbird) wrote in
om:

"Steven P. McNicoll" wrote in
message
link.net.
..

The problem with navaid radial/distance is that it relies
on the navaid location being known to the flight data
processing computer. If the computer doesn't recognize
the base fix it won't process it.

Steve,

How does the flight data processing computer handle direct
VOR routing between VORs it doesn't recognize? Does it
barf on that too, or is this barfing specific to VOR
radial-distance?

If it doesn't recognize the VOR, it would have to barf on both.

--
Regards,

Stan

"Snowbird" wrote in message
om...

How does the flight data processing computer handle direct VOR
routing between VORs it doesn't recognize? Does it barf on that
too, or is this barfing specific to VOR radial-distance?


It will barf on that too. It can't process to a VOR/radial/distance fix if
it does not recognize the VOR the fix is based on. It'd be like asking you
to drive 50 miles due east of a town that does not appear on your road map.

Well, Chip, that is easily remedied. A west coast controller who flies a Baron in the low altitude structure recommends designating a major VOR along the route in the correct direction to obviate that kind of confusion. Beyond that, he is in the lat-long camp.

Bob Gardner

"Chip Jones" wrote in message hlink.net...
Oh the shame! :-)

One of Don's problems with L/L's is that by themselves they don't tell the controller diddly about which direction you will be headed. They are just a jumble of numbers on a flight progress strip to a busy ATCS. Secondly, because they don't tell the controller diddly about which direction you will be headed, the controller has no way of verifying that they are correctly filed by you, DUATS or FSS until after you get radar identified. One digit of mistake on the filer's part can cause mountians of headaches for ATC with both IFR separation requirements and just plain old inter-ATC coordination fumbles. And speaking of radar identified, what happens if you *don't* get radar identified...?

File Lat/ longs at your pleasure, but don't be surprised at the results. Down here in ATC-land, we'll probably be surprised for you...

Chip, ZTL
"Bob Gardner" wrote in message et...
I know Don Brown. He is a good 'ol country boy, and an entertaining writer, but he is not a pilot. His aviation world is circumscribed by the AIM and Air Traffic Control Handbook, with no latitude (no pun intended) allowed. His Avweb column about filing IFR is almost perfect, but there are airplane-owning controllers around the country who will tell you that host computers throughout the system recognize lat-longs, while a radial-distance from a VORTAC several hundred miles away might get bounced because the VORTAC is not in the host computer. Keep filing lat-longs where appropriate even if you never get up to FL390.

Bob Gardner

"Bob Gardner" wrote in message . net...
I know Don Brown. He is a good 'ol country boy, and an entertaining
writer, but he is not a pilot. His aviation world is circumscribed by
the AIM and Air Traffic Control Handbook, with no latitude (no pun
intended) allowed. His Avweb column about filing IFR is almost perfect,
but there are airplane-owning controllers around the country who will
tell you that host computers throughout the system recognize lat-longs,
while a radial-distance from a VORTAC several hundred miles away might
get bounced because the VORTAC is not in the host computer. Keep filing
lat-longs where appropriate even if you never get up to FL390.

Bob,

I think two of Don's concerns with lat-longs a
1) they provide ATC with no information about what direction you're
headed, so coordination with other facilities is difficult. In fact,
initial separation is problematic.
2) ATC apparently has no means to verify a lat-long against an
airport identifier or navaid to ensure that the lat-long was entered
correctly. Serious lack of backup or verification redundancy.

I don't know about you, but I don't want to be in either place.

My suggested solution for filing GPS direct is:
1) provide a VOR radial-distance waypoint which will be recognized --
one w/in the facility's boundry is a good bet. That way ATC knows
which direction you're headed from a waypoint which will be in their
host computer, and coordination is easier for them
2) put a radial-distance from a VOR near your destination into your
flight plan. if you're crossing several centers, make sure there's
one in each center.

I note that the above does not fulfil the letter of the AIM for
direct flights, which require that a direct flight begin and end
over a ground-based navaid (at least as I read it) but I feel
it fulfills the spirit, in that it allows ATC to know which way
I'm headed without guessing and to verify any lat-longs in a
straighforward way. I object to the letter of the AIM because
AFAIK VORs near busy airports qualify as "designated collision
points" and I see no reason to detour and fly over one when it's
not necessary.

I also note that DUATS flightplanner direct routing for GPS/RNAV
makes the above stone-simple because it spits out a list of such
waypoints along one's route of flight.

3) put some comment about a major, recognizeable waypoint
into your remarks section. ie if I'm flying from s. FL to our new
homebase airport, it's a cinch that the Miami Center computer won't
have a clue where 1H0 is, but if I put "remarks 1H0 7 SW KSTL"
hopefully everyone in the ATC system now grasps which way
I'm intending to fly. If the lat-long has me flying in the opposite
direction, there's clearly a mistake.

This said: I don't understand your comment about why one should
file lat-longs. Yes, VORS outside a center's airspace might
not be in the host computer, but this doesn't stop pilots from
flying Victor airways or direct VOR routing which includes
VORs the ATC computer for the facility originating the flight
won't recognize. What I know about ATC host computers could be
printed on a penny and lost, but surely they have some mechanism
for accepting "I don't know where that VOR is, but the routing
through my part of the system looks OK so off you go".

So it seems to me that the lat-long vs. a VOR-radial-distance
waypoint becomes an issue only if you have NOT included some
waypoint within the airspace of each facility along the way.
And that's a no-no, both in terms of the AIM's instructions
for filing direct and in terms of filing in a manner ATC can
deal with easily.

Perhaps I'm just dense here, but we file GPS direct to obscure
airports (along with the pound of flesh nearest Don Brown's
heart, I assume, sorry ) all the time. We just make sure to
include at least one VOR degree-distance waypoint for each facility
we cross, lately we've also taken to including a remark about
our destination vs. a major airport if that's possible. We've
never had anyone request a lat-long from us.

In a sane world, of course, each controller would be able to
instantly convert a lat-long into some bearing from a recognizeable
navaid or airport. It could be done on a used $50 Palm Pilot.
But that would make too much sense.

Best,
Sydney

I did not intend that pilots file lat-longs exclusively, just when they need
something far enough away from the departure airport that a radial-distance
might not be in the local host computer. I agree that filing a major VOR in
the initial direction will get things started off on the right foot.

Bob Gardner

"Snowbird" wrote in message
om...
"Bob Gardner" wrote in message
. net...
I know Don Brown. He is a good 'ol country boy, and an entertaining
writer, but he is not a pilot. His aviation world is circumscribed by
the AIM and Air Traffic Control Handbook, with no latitude (no pun
intended) allowed. His Avweb column about filing IFR is almost perfect,
but there are airplane-owning controllers around the country who will
tell you that host computers throughout the system recognize lat-longs,
while a radial-distance from a VORTAC several hundred miles away might
get bounced because the VORTAC is not in the host computer. Keep filing
lat-longs where appropriate even if you never get up to FL390.

Bob,

I think two of Don's concerns with lat-longs a
1) they provide ATC with no information about what direction you're
headed, so coordination with other facilities is difficult. In fact,
initial separation is problematic.
2) ATC apparently has no means to verify a lat-long against an
airport identifier or navaid to ensure that the lat-long was entered
correctly. Serious lack of backup or verification redundancy.

I don't know about you, but I don't want to be in either place.

My suggested solution for filing GPS direct is:
1) provide a VOR radial-distance waypoint which will be recognized --
one w/in the facility's boundry is a good bet. That way ATC knows
which direction you're headed from a waypoint which will be in their
host computer, and coordination is easier for them
2) put a radial-distance from a VOR near your destination into your
flight plan. if you're crossing several centers, make sure there's
one in each center.

I note that the above does not fulfil the letter of the AIM for
direct flights, which require that a direct flight begin and end
over a ground-based navaid (at least as I read it) but I feel
it fulfills the spirit, in that it allows ATC to know which way
I'm headed without guessing and to verify any lat-longs in a
straighforward way. I object to the letter of the AIM because
AFAIK VORs near busy airports qualify as "designated collision
points" and I see no reason to detour and fly over one when it's
not necessary.

I also note that DUATS flightplanner direct routing for GPS/RNAV
makes the above stone-simple because it spits out a list of such
waypoints along one's route of flight.

3) put some comment about a major, recognizeable waypoint
into your remarks section. ie if I'm flying from s. FL to our new
homebase airport, it's a cinch that the Miami Center computer won't
have a clue where 1H0 is, but if I put "remarks 1H0 7 SW KSTL"
hopefully everyone in the ATC system now grasps which way
I'm intending to fly. If the lat-long has me flying in the opposite
direction, there's clearly a mistake.

This said: I don't understand your comment about why one should
file lat-longs. Yes, VORS outside a center's airspace might
not be in the host computer, but this doesn't stop pilots from
flying Victor airways or direct VOR routing which includes
VORs the ATC computer for the facility originating the flight
won't recognize. What I know about ATC host computers could be
printed on a penny and lost, but surely they have some mechanism
for accepting "I don't know where that VOR is, but the routing
through my part of the system looks OK so off you go".

So it seems to me that the lat-long vs. a VOR-radial-distance
waypoint becomes an issue only if you have NOT included some
waypoint within the airspace of each facility along the way.
And that's a no-no, both in terms of the AIM's instructions
for filing direct and in terms of filing in a manner ATC can
deal with easily.

Perhaps I'm just dense here, but we file GPS direct to obscure
airports (along with the pound of flesh nearest Don Brown's
heart, I assume, sorry ) all the time. We just make sure to
include at least one VOR degree-distance waypoint for each facility
we cross, lately we've also taken to including a remark about
our destination vs. a major airport if that's possible. We've
never had anyone request a lat-long from us.

In a sane world, of course, each controller would be able to
instantly convert a lat-long into some bearing from a recognizeable
navaid or airport. It could be done on a used $50 Palm Pilot.
But that would make too much sense.

Best,
Sydney