How much protection on approach?

[Michael]

How much protection do we have on an off-field VOR approach? I was
always under the impression that as long as the equipment was within
tolerances for an airborne VOR receiver check (+/- 6 degrees) and the
approach was flown to PTS tolerances (no more than 3/4 scale
deflection) it was impossible to hit anything. I now know this is not
necessarily true.

The approach in question is the VOR-B to LVJ; the URL for the plate is
http://www.myairplane.com/databases/approach/SouthCentral/LVJ_vB.pdf

The long and the short of it is this. The Cat-A altitude minimum on
the approach is 520 MSL; there is a 1200 ft MSL tower less than 4 nm
South of the airport, and the FAC is 260. The VOR is 25.8 nm from the
MAP, which is over the field. No matter how you slice it, that's less
than 9 degrees off the FAC. 3/4 scale deflecion on a VOR is more than
7 degrees in itself.

So what am I missing?

Michael

[EDR]

In article >, Michael
> wrote:

> How much protection do we have on an off-field VOR approach? I was
> always under the impression that as long as the equipment was within
> tolerances for an airborne VOR receiver check (+/- 6 degrees) and the
> approach was flown to PTS tolerances (no more than 3/4 scale
> deflection) it was impossible to hit anything. I now know this is not
> necessarily true.
>
> The approach in question is the VOR-B to LVJ; the URL for the plate is
> http://www.myairplane.com/databases/approach/SouthCentral/LVJ_vB.pdf
>
> The long and the short of it is this. The Cat-A altitude minimum on
> the approach is 520 MSL; there is a 1200 ft MSL tower less than 4 nm
> South of the airport, and the FAC is 260. The VOR is 25.8 nm from the
> MAP, which is over the field. No matter how you slice it, that's less
> than 9 degrees off the FAC. 3/4 scale deflecion on a VOR is more than
> 7 degrees in itself.

Without going into my copy of TERPS, I believe the obstruction
clearance is a 20:1 slope for non-precision approaches.

[Roy Smith]

In article >,
(Michael) wrote:

> How much protection do we have on an off-field VOR approach? I was
> always under the impression that as long as the equipment was within
> tolerances for an airborne VOR receiver check (+/- 6 degrees) and the
> approach was flown to PTS tolerances (no more than 3/4 scale
> deflection) it was impossible to hit anything. I now know this is not
> necessarily true.
>
> The approach in question is the VOR-B to LVJ; the URL for the plate is
> http://www.myairplane.com/databases/approach/SouthCentral/LVJ_vB.pdf
>
> The long and the short of it is this. The Cat-A altitude minimum on
> the approach is 520 MSL; there is a 1200 ft MSL tower less than 4 nm
> South of the airport, and the FAC is 260. The VOR is 25.8 nm from the
> MAP, which is over the field. No matter how you slice it, that's less
> than 9 degrees off the FAC. 3/4 scale deflecion on a VOR is more than
> 7 degrees in itself.
>
> So what am I missing?

The tower, I hope!

[Ron Rosenfeld]

On 8 Jan 2004 11:41:53 -0800, (Michael) wrote:

>How much protection do we have on an off-field VOR approach? I was
>always under the impression that as long as the equipment was within
>tolerances for an airborne VOR receiver check (+/- 6 degrees) and the
>approach was flown to PTS tolerances (no more than 3/4 scale
>deflection) it was impossible to hit anything. I now know this is not
>necessarily true.
>
>The approach in question is the VOR-B to LVJ; the URL for the plate is
>http://www.myairplane.com/databases/approach/SouthCentral/LVJ_vB.pdf
>
>The long and the short of it is this. The Cat-A altitude minimum on
>the approach is 520 MSL; there is a 1200 ft MSL tower less than 4 nm
>South of the airport, and the FAC is 260. The VOR is 25.8 nm from the
>MAP, which is over the field. No matter how you slice it, that's less
>than 9 degrees off the FAC. 3/4 scale deflecion on a VOR is more than
>7 degrees in itself.
>
>So what am I missing?
>
>Michael

Just some discussion without going into the math of what happens if you are
flying to the maximum allowed PTS variance.

Assuming I remember my math and have read the rules correctly:

A line from the tower perpendicular to the FAC would intersect at about 25
miles from the VOR. At that point, the primary protected area should be
about 2.25 miles on either side of the centerline; and the secondary area
about 5/6 mile or a total of about 3.082NM.

My VFR chart shows that tower to be about 3.35 NM from the FAC centerline,
so it is outside the protected area. My VFR chart could be off, and one
should really be using a USGS topographical map, but I don't have one for
that area.

So the first conclusion is that that tower is, indeed, outside of the
protected area.

In the primary area, you have 250' obstacle clearance, and at the outer
edge of the secondary area, you have zero clearance.

From the VOR to the outer edge of the secondary area, at 25 miles from the
VOR, would be a difference (error) from the FAC of 7°.

So to hit the tower, you would have to be more than 7° off course. Again,
one should be using topographical maps, but if the VFR charts are accurate,
it looks like a 7.6° error would put you into the tower.

I believe the FAA assumes that total VOR system error will be no more than
±4.5° (including your VOR error and station errors) 95% of the time.

So -- fly safe!


Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

[Snowbird]

(Michael) wrote in message >...
> How much protection do we have on an off-field VOR approach? I was
> always under the impression that as long as the equipment was within
> tolerances for an airborne VOR receiver check (+/- 6 degrees) and the
> approach was flown to PTS tolerances (no more than 3/4 scale
> deflection) it was impossible to hit anything. I now know this is not
> necessarily true.
<...> So what am I missing?

An approach certified GPS :)

Sorry couldn't resist...but I recall we've had past
discussions where you opined that a GPS approach
didn't give you much in the way of capability and
this is one of the places where I feel the ability to
legally request and fly GPS approaches is more than
just an issue of whether there are other IAPs and
what their minima are.

Early on, I did the math on a bunch of approaches
around here, approaches where the VOR is seriously
off-field, and came to the similar conclusions. That
one could be w/in tolerances for a VOT check, be
just over half-scale deflection, and smack into
something. Heck you can center the needle on the
VOT check, center the needle on the approach,
and come out of a cloud with the airport over
THAR.

6 degrees and 3/4 scale deflection clearly aren't
good enough.

Cheers,
Sydney

[Julian Scarfe]

"Michael" > wrote in message
m...
> How much protection do we have on an off-field VOR approach? I was
> always under the impression that as long as the equipment was within
> tolerances for an airborne VOR receiver check (+/- 6 degrees) and the
> approach was flown to PTS tolerances (no more than 3/4 scale
> deflection) it was impossible to hit anything. I now know this is not
> necessarily true.
>
> The approach in question is the VOR-B to LVJ; the URL for the plate is
> http://www.myairplane.com/databases/approach/SouthCentral/LVJ_vB.pdf
>
> The long and the short of it is this. The Cat-A altitude minimum on
> the approach is 520 MSL; there is a 1200 ft MSL tower less than 4 nm
> South of the airport, and the FAC is 260. The VOR is 25.8 nm from the
> MAP, which is over the field. No matter how you slice it, that's less
> than 9 degrees off the FAC. 3/4 scale deflecion on a VOR is more than
> 7 degrees in itself.

From my reading of TERPS para 513, the primary area is defined by a
trapezium that is 2 miles wide at the facility and 5 miles wide at 30 miles
from the facility (which is the furthest permitted). The secondary area is
a mile wider on each side at 30 miles. So at 30 miles the deviation against
which you are protected is 3.5 miles. As you say, that's about 7 degrees.
Scary stuff!

Julian Scarfe

[Doug]

My take on this is that such specifications exist, but we, as pilots,
don't have access to them. This is due to their complexity. However,
if we pilots fly reasonable approaches, and don't get "too far" off
course, we will be safe. In this case, the tower is 4 miles away from
the field. THAT is a long way. If you take a look at the approach to
ERIE, Colorado, there is a tower that is less than a mile off course,
and only 100' below where you are supposed to be. Very scary. All it
would take is a combination of bad altimeter setting, or being a
little low, and flying a couple of dots off. I always am very, very
cautious flying approaches in IMC if I have never flown in visual
conditions to acertain the radio tower and hill situation. There are
some frightenly close obstructions out there. Nevertheless, we as
pilots seem to be doing a fairly good job, as we are not plowing into
such obstacles at a very high rate. So the system seems to be working.
Certainly you bring up a good point. I would like to see the zone of
protection marked on the charts in some way. This would obviously be a
major change from current charting system.

(Michael) wrote in message >...
> How much protection do we have on an off-field VOR approach? I was
> always under the impression that as long as the equipment was within
> tolerances for an airborne VOR receiver check (+/- 6 degrees) and the
> approach was flown to PTS tolerances (no more than 3/4 scale
> deflection) it was impossible to hit anything. I now know this is not
> necessarily true.
>
> The approach in question is the VOR-B to LVJ; the URL for the plate is
> http://www.myairplane.com/databases/approach/SouthCentral/LVJ_vB.pdf
>
> The long and the short of it is this. The Cat-A altitude minimum on
> the approach is 520 MSL; there is a 1200 ft MSL tower less than 4 nm
> South of the airport, and the FAC is 260. The VOR is 25.8 nm from the
> MAP, which is over the field. No matter how you slice it, that's less
> than 9 degrees off the FAC. 3/4 scale deflecion on a VOR is more than
> 7 degrees in itself.
>
> So what am I missing?
>
> Michael

[Michael]

(Snowbird) wrote
> An approach certified GPS :)
>
> Sorry couldn't resist...but I recall we've had past
> discussions where you opined that a GPS approach
> didn't give you much in the way of capability

Relative to a VFR GPS. With a VFR GPS, this is a non-issue since you
would never be 3.5 miles from the airport in the first place. Sorry,
no sale. However, if the point you were trying to make is that it
would be safer to shoot a VOR appproach using an uncertified VFR GPS
rather than the legally usable VOR receiver, the point is made :).

> 6 degrees and 3/4 scale deflection clearly aren't
> good enough.

Clearly.

Michael

[Snowbird]

(Michael) wrote in message >...
> (Snowbird) wrote
> > An approach certified GPS :)
> >
> > Sorry couldn't resist...but I recall we've had past
> > discussions where you opined that a GPS approach
> > didn't give you much in the way of capability

> However, if the point you were trying to make is that it
> would be safer to shoot a VOR appproach using an uncertified VFR GPS
> rather than the legally usable VOR receiver, the point is made :).

No, that wasn't my point, although it's certainly valid -- I always
felt much safer flying an NDB approach while following it on GPS.
It definately does improve the safety.

Here, let me restore the point I was trying to make:
>> I feel the ability to legally request and fly GPS approaches
>> is more than just an issue of whether there are other IAPs and
>> what their minima are.

Approaches where the navaid is off the field are of necessity
constrained by the location of the navaid. Stand-alone GPS
approaches IMO add significant capability vs. using VFR GPS
to fly an impromptu overlay approach.

You don't have to agree with my point, but please don't delete
it and then surmise that I must have been making a different
one.

Cheers,
Sydney

[Michael]

(Snowbird) wrote
> Here, let me restore the point I was trying to make:
> >> I feel the ability to legally request and fly GPS approaches
> >> is more than just an issue of whether there are other IAPs and
> >> what their minima are.
>
> Approaches where the navaid is off the field are of necessity
> constrained by the location of the navaid.

Actually, whether the navaid is on or off the field, there are still
plenty of constraints on the approach unless it's in the middle of
nowhere on flat ground. Check out the NDB and GPS approaches to my
home field of EYQ for a perfect example of what happens when you're
not in the middle of nowhere.

> Stand-alone GPS
> approaches IMO add significant capability vs. using VFR GPS
> to fly an impromptu overlay approach.

I fail to see how this is relevant to the protection offered on
approach. The hazard on the approach into LVJ is a 1200 ft tower.
That tower is actually much CLOSER to the FAC on the GPS approach.

It's simply that the GPS (VFR or IFR) is so much more accurate than
the VOR, and thus the pilot can easily avoid the hazard without the
need to keep the needle perfectly centered. If a VFR GPS is used to
back up the VOR approach, then I would argue that safety is increased
over the standalone GPS approach, since (a) the hazard is
significantly farther from the FAC and (b) a second source of
navigation, relying on a completely different signal source, is
available as a sanity check.

> You don't have to agree with my point, but please don't delete
> it and then surmise that I must have been making a different
> one.

It simply never occurred to me that your point was that having the IFR
rather than a VFR GPS was a safety issue, especially when flying into
an airport like LVJ. If that is your point, I see no support for it
whatsoever.

One thing you are failing to realize is that the reason for the use of
the MHF VOR/DME as the basis of the sole non-GPS approach to LVJ has
NOTHING to do with the lack of a suitable closer navaid. HUB VOR/DME
is much closer, and would allow an approach to 32 with straight-in
minima. In fact there was such an approach. It was decomissioned
because too many people were using it. There are several flight
schools on the field, and when the CFII's filed IFR they were
interfering with arrivals into Hobby. Once IFR GPS becomes
sufficiently popular, you can rest assured the GPS 32 approach into
LVJ will be decomissioned as well, and will probably be replaced with
an approach much like the VOR-B.

Michael

[Roy Smith]

(Michael) wrote:
> I fail to see how this is relevant to the protection offered on
> approach. The hazard on the approach into LVJ is a 1200 ft tower.
> That tower is actually much CLOSER to the FAC on the GPS approach.

Why not call up the local tracon, ask to speak to the procedures guru,
and find out from somebody who is in a position to know for sure?

[Michael]

Roy Smith > wrote
> > I fail to see how this is relevant to the protection offered on
> > approach. The hazard on the approach into LVJ is a 1200 ft tower.
> > That tower is actually much CLOSER to the FAC on the GPS approach.
>
> Why not call up the local tracon, ask to speak to the procedures guru,
> and find out from somebody who is in a position to know for sure?

To know what for sure?

Michael

[Snowbird]

(Michael) wrote in message >...

> > Approaches where the navaid is off the field are of necessity
> > constrained by the location of the navaid.

> Actually, whether the navaid is on or off the field, there are still
> plenty of constraints on the approach unless it's in the middle of
> nowhere on flat ground.

Granted. Let's do the math:

GPS approach: constrained by airspace, terrain, and obstructions

off field navaid approach: constrained by airspace, terrain, obstructions
*and* the location of the navaid.

It appears pretty clear to me that the latter is more constrained.
YMMV

> > Stand-alone GPS
> > approaches IMO add significant capability vs. using VFR GPS
> > to fly an impromptu overlay approach.

> I fail to see how this is relevant to the protection offered on
> approach.

Yes, I know. We've had this discussion before. It seems
obvious to me that it's relevant. In the case you cite,
apparently the GPS approach doesn't avoid the tower. However,
with a GPS, the capability to establish a waypoint at a
convenient spot clearly allows the approach designer to work
around terrain and obstructions in a way that an approach
based on one or two ground navaids can not.

> It's simply that the GPS (VFR or IFR) is so much more accurate than
> the VOR, and thus the pilot can easily avoid the hazard without the
> need to keep the needle perfectly centered.

This is definately a factor, but it's not the factor to which
I was referring.

> If a VFR GPS is used to
> back up the VOR approach, then I would argue that safety is increased
> over the standalone GPS approach, since (a) the hazard is
> significantly farther from the FAC and (b) a second source of
> navigation, relying on a completely different signal source, is
> available as a sanity check.

You may even be correct in this instance, but I don't think that
can be generalized, nor can it be generalized that the capabilies/
safety of IFR and VFR GPS are equal.

I understand some VFR GPS can be set to precise course guidance
(full deflection = 0.3 miles) and of course a VFR GPS can be
installed so as to have the same features of IFR GPS -- RAIM
prediction and monitoring, installed antenna etc. But many
are not installed or set up that way.

> > You don't have to agree with my point, but please don't delete
> > it and then surmise that I must have been making a different
> > one.

> It simply never occurred to me that your point was that having the IFR
> rather than a VFR GPS was a safety issue

I apologize for failing to write with sufficient clarity, nor to
make clear that I was speaking to a generalized point not of your
specific airport.

> If that is your point, I see no support for it whatsoever.

Yes, I know. As I said, we've had this discussion before.

Cheers,
Sydney

[Roy Smith]

In article >,
(Michael) wrote:

> Roy Smith > wrote
> > > I fail to see how this is relevant to the protection offered on
> > > approach. The hazard on the approach into LVJ is a 1200 ft tower.
> > > That tower is actually much CLOSER to the FAC on the GPS approach.
> >
> > Why not call up the local tracon, ask to speak to the procedures guru,
> > and find out from somebody who is in a position to know for sure?
>
> To know what for sure?

Why the approach was designed the way it was, how the TERPS rules were
applied, etc.

Maybe the approach really is broken and your pointing it out will get it
fixed. Maybe the tower is just charted in the wrong place and there's
really nothing wrong with the approach (I've see that before).

I've found problems with charts and reported them. They get fixed. If
people never report them, they stay broken. It's certainly interesting
to discuss is on usenet, but it's probably not an effective way to get
problems fixed.

[Bob Gardner]

Procedures used to be designed by the Region, but those offices were shut
down and the whole works moved to either Sacramento or Oke City, I can't
remember which. I learned a lot when I was able to pick up the phone and
talk to the designer of an approach I had questions about...but that is no
longer the case. To my knowledge, procedures were never designed by TRACONS.

Bob Gardner

"Roy Smith" > wrote in message
...
> (Michael) wrote:
> > I fail to see how this is relevant to the protection offered on
> > approach. The hazard on the approach into LVJ is a 1200 ft tower.
> > That tower is actually much CLOSER to the FAC on the GPS approach.
>
> Why not call up the local tracon, ask to speak to the procedures guru,
> and find out from somebody who is in a position to know for sure?

[Michael]

(Snowbird) wrote
> Yes, I know. We've had this discussion before. It seems
> obvious to me that it's relevant. In the case you cite,
> apparently the GPS approach doesn't avoid the tower. However,
> with a GPS, the capability to establish a waypoint at a
> convenient spot clearly allows the approach designer to work
> around terrain and obstructions in a way that an approach
> based on one or two ground navaids can not.

And if the approach designer was (a) cognizant of the real world, and
not simply relying on rules (TERPS) and (b) was not constrained by the
need to expedite airline traffic at any cost to GA, this might even be
important. However, in the real world where neither (a) nor (b) is
true, I just don't believe it's an important factor.

> > If a VFR GPS is used to
> > back up the VOR approach, then I would argue that safety is increased
> > over the standalone GPS approach, since (a) the hazard is
> > significantly farther from the FAC and (b) a second source of
> > navigation, relying on a completely different signal source, is
> > available as a sanity check.
>
> You may even be correct in this instance, but I don't think that
> can be generalized

With respect to the first part, of course not. With respect to the
second (a completely different signal source) I absolutely do not
concur. In all cases, where a GPS is used in an overlay mode with the
underlying navaid still monitored, the underlying navaid, while in
general less accurate than the GPS, still provides a sanity check. A
standalone GPS approach lacks such a check in almost all cases.

This is particularly problematic due to the nature of the GPS signal.
It's quite unlikely that GPS (VFR or IFR) will be spoofed (whether
intentionally, or unintentionally due to signal reflections and/or
interference) in such a way as to cause a small error in position.
However, the underlying math of position determination by signal delay
from multiple sources of known position is such that it is possible to
spoof the device with a reflected signal in such a way as to cause it
to give reasonable track and speed information but a grossly erroneous
position. I've never actually seen a GPS do this (though I have seen
a math geek prove it's possible) but I HAVE seen LORAN do this.

Even a very low accuracy signal (such as a VOR 30 miles from the
field) will provide a crosscheck more than accurate enough to catch
such a problem. The same is not necessarily true of RAIM.

> nor can it be generalized that the capabilies/
> safety of IFR and VFR GPS are equal.
>
> I understand some VFR GPS can be set to precise course guidance
> (full deflection = 0.3 miles) and of course a VFR GPS can be
> installed so as to have the same features of IFR GPS -- RAIM
> prediction and monitoring, installed antenna etc. But many
> are not installed or set up that way.

This is absolutely correct. IFR GPS provides a certain 'guaranteed'
level of performance. I put guaranteed in quotes because I don't find
the software methods used particularly impressive, and I used to write
similar software for a living before I became a manager and ceased to
do anything useful.

A VFR GPS provides whatever level of performance you wish to have and
are willing to pay for. However, even the highest level of VFR GPS
performance comes at a lower cost than the cheapest possible IFR GPS.

Michael

[Dave Buckles]

Bob Gardner wrote:
> Procedures used to be designed by the Region, but those offices were shut
> down and the whole works moved to either Sacramento or Oke City, I can't
> remember which. I learned a lot when I was able to pick up the phone and
> talk to the designer of an approach I had questions about...but that is no
> longer the case. To my knowledge, procedures were never designed by TRACONS.
>
> Bob Gardner
>
> "Roy Smith" > wrote in message
> ...

OKC. I have a friend working there now; matter of fact, he just
finished designing two approaches for an airport I frequent (*yay!*).
Their website is http://www.naco.faa.gov, and you're looking for the
National Flight Procedures Office. They can be reached at:
AVN-100
C. Fred Anderson, Manager
Phone: 405-954-3027
Fax: 405-954-4236

AVN-101
Bradley W. Rush, Assistant Manager
Phone: 405-954-0188
Fax: 405-954-4236

--Dave Buckles

http://www.flight-instruction.com

[Michael]

Roy Smith > wrote
> Why the approach was designed the way it was, how the TERPS rules were
> applied, etc.

This is well known locally. The approach was designed the way it was
to keep from interfering with Hobby operations. A North/South
approach would be guaranteed to interfere with Hobby, which is just a
few miles almost due North of LVJ. There used to be such an approach,
and it was decomissioned for that reason.

> Maybe the approach really is broken and your pointing it out will get it
> fixed. Maybe the tower is just charted in the wrong place and there's
> really nothing wrong with the approach (I've see that before).

The approach is not broken. Bob Gardner was nice enough to send me
the appropriate excerpt from TERPS (thanks Bob - but why didn't you
just post it?) and the tower is just outside the secondary area, and
thus not a factor. I simply did not know that there was no
requirement for the protected area to be large enough to contain
allowed instrument error and maximum allowable (by the PTS) deviation.
Now I do.

The tower is charted correctly - I know where it is, there is nothing
to check.

> I've found problems with charts and reported them. They get fixed.

Yes, I've had the same experience. However, those were actual
charting errors. This is not one of them. The error was on my part -
I did not know what the actual protected area was like, and assumed it
was larger than it really was.

It was a little over a year ago that I had a similar learning
experience. I discovered that when an approach is temporarily NOTAM'd
NA, the plate is not so noted, even if the approach is NA for years.
So you have current plates, a standard briefing with NOTAM's, and
unless you specifically ask for Class II NOTAM's, you will never know
the approach is not available until you ask for it. The long and the
short of it is that most IFR pilots are not aware of this (nobody at
my home field was) but that's the way the system works. This is more
of the same - the system is working as designed, but most pilots are
not aware that this is proper. I did an informal survey at my home
field, and none of the IFR pilots (including an airline captain and a
DE) knew about this. I wondered then how many more gotchas there were
in the system. I'm still wondering.

I am not far from deciding that the system is so full of gotchas that
GA IFR is simply not a reasonable thing to do.

Michael

[Julian Scarfe]

"Michael" > wrote in message
m...

> Bob Gardner was nice enough to send me
> the appropriate excerpt from TERPS

TERPS is available as a PDF or photocopied images at
http://www.dot.state.fl.us/aviation/text_version/fedpub.htm

It's large (28 Mb) but interesting.

[Barry]

> So you have current plates, a standard briefing with NOTAM's, and
> unless you specifically ask for Class II NOTAM's, you will never know
> the approach is not available until you ask for it.

Yes, the NOTAM system is still a mess, but it's a little easier to get the
published NOTAMs now that they're on line:

http://www1.faa.gov/NTAP/

Barry

[Michael]

"Barry" > wrote
> > So you have current plates, a standard briefing with NOTAM's, and
> > unless you specifically ask for Class II NOTAM's, you will never know
> > the approach is not available until you ask for it.
>
> Yes, the NOTAM system is still a mess, but it's a little easier to get the
> published NOTAMs now that they're on line:
>
> http://www1.faa.gov/NTAP/

Yes, that's great when you can get on the net. But the reality is
that if the airport with the NA approach is local, you're going to
know about it. If you get the briefing on DUATS, you can get it in
text format, get the Class II's, and search them for your
destination/alternate with a text editor.

The real problem occurs when you're on a trip, are forced to divert
due to unexpected weather, and find yourself on the ground replanning
your trip without computer access. Now your only option for getting
Class II NOTAM's is FSS. But guess what - if the weather was bad for
you, it was bad for lots of other people. FSS is going to be busy.

I'm not saying it's impossible - once you're aware of that particular
gotcha, you can work around it. The problem is that it's not
something most IFR pilots are aware of.

Michael