HVN VOR-A -- why such a high MDA?

[Roy Smith]

The VOR-A at New Haven
(http://www.myairplane.com/databases/approach/pdfs/00671VG2.PDF) has an
MDA of 720, which is about 300 feet higher than the towers in the area.
The VOR-2
(http://www.myairplane.com/databases/approach/pdfs/00671VG2.PDF) gets
you down to 380, and has to deal with the same towers. Why does it get
to have an MDA 340 feet lower than the VOR-A?

In fact, the VOR-A is almost perfectly lined up with runway 32; I don't
see why it couldn't have been the VOR-32 with an MDA about 300 feet
lower. Any of you TERPs-heads out there understand what's going on here?

[Steven P. McNicoll]

"Roy Smith" > wrote in message
...
>
> The VOR-A at New Haven
> (http://www.myairplane.com/databases/approach/pdfs/00671VG2.PDF) has an
> MDA of 720, which is about 300 feet higher than the towers in the area.
> The VOR-2
> (http://www.myairplane.com/databases/approach/pdfs/00671VG2.PDF) gets
> you down to 380, and has to deal with the same towers. Why does it get
> to have an MDA 340 feet lower than the VOR-A?
>
> In fact, the VOR-A is almost perfectly lined up with runway 32; I don't
> see why it couldn't have been the VOR-32 with an MDA about 300 feet
> lower. Any of you TERPs-heads out there understand what's going on here?
>

Apples and oranges. You're comparing the straight-in MDA of the VOR RWY 2
to the MDA of the VOR-A. The VOR-A has only a circling MDA, which is 720
feet, the same as the circling MDA of the VOR RWY 2.

[Roy Smith]

In article .net>,
"Steven P. McNicoll" > wrote:

> "Roy Smith" > wrote in message
> ...
> >
> > The VOR-A at New Haven
> > (http://www.myairplane.com/databases/approach/pdfs/00671VG2.PDF) has an
> > MDA of 720, which is about 300 feet higher than the towers in the area.
> > The VOR-2
> > (http://www.myairplane.com/databases/approach/pdfs/00671VG2.PDF) gets
> > you down to 380, and has to deal with the same towers. Why does it get
> > to have an MDA 340 feet lower than the VOR-A?
> >
> > In fact, the VOR-A is almost perfectly lined up with runway 32; I don't
> > see why it couldn't have been the VOR-32 with an MDA about 300 feet
> > lower. Any of you TERPs-heads out there understand what's going on here?
> >
>
> Apples and oranges. You're comparing the straight-in MDA of the VOR RWY 2
> to the MDA of the VOR-A. The VOR-A has only a circling MDA, which is 720
> feet, the same as the circling MDA of the VOR RWY 2.

Yeah, but the point of my question was, "Why didn't they publish
straight-in minimums for the VOR-A and call it the VOR-32?"

[Steven P. McNicoll]

"Roy Smith" > wrote in message
...
>>
>> Apples and oranges. You're comparing the straight-in MDA of the VOR RWY
>> 2
>> to the MDA of the VOR-A. The VOR-A has only a circling MDA, which is 720
>> feet, the same as the circling MDA of the VOR RWY 2.
>>
>
> Yeah, but the point of my question was, "Why didn't they publish
> straight-in minimums for the VOR-A and call it the VOR-32?"
>

I don't know, I'm no TERPS expert, but I'd wager it's because the MAP is
beyond the runway 32 threshold.

[Andrew Sarangan]

"Steven P. McNicoll" > wrote in
link.net:

>
> "Roy Smith" > wrote in message
> ...
>>>
>>> Apples and oranges. You're comparing the straight-in MDA of the VOR
>>> RWY 2
>>> to the MDA of the VOR-A. The VOR-A has only a circling MDA, which
>>> is 720 feet, the same as the circling MDA of the VOR RWY 2.
>>>
>>
>> Yeah, but the point of my question was, "Why didn't they publish
>> straight-in minimums for the VOR-A and call it the VOR-32?"
>>
>
> I don't know, I'm no TERPS expert, but I'd wager it's because the MAP
> is beyond the runway 32 threshold.
>
>
>

But there are straight-in approaches with the MAP well past the runway
threshold. Look at VOR24@RID for example.

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[Ron Rosenfeld]

On Sat, 30 Oct 2004 19:34:19 -0400, Roy Smith > wrote:

>The VOR-A at New Haven
>(http://www.myairplane.com/databases/approach/pdfs/00671VG2.PDF) has an
>MDA of 720, which is about 300 feet higher than the towers in the area.
>The VOR-2
>(http://www.myairplane.com/databases/approach/pdfs/00671VG2.PDF) gets
>you down to 380, and has to deal with the same towers. Why does it get
>to have an MDA 340 feet lower than the VOR-A?
>
>In fact, the VOR-A is almost perfectly lined up with runway 32; I don't
>see why it couldn't have been the VOR-32 with an MDA about 300 feet
>lower. Any of you TERPs-heads out there understand what's going on here?

I'm not sure, but I wonder if it has something to do with the Missed
Approach path. The MA segment for the VOR-A seems to come a lot closer to
the 400+' towers than does the MA segment for the VOR-2.


--ron

[Greg Esres]

<<In fact, the VOR-A is almost perfectly lined up with runway 32;>>

In addition to the runway alignment issue, there are two other
criteria used for issuing straight in minimums: descent gradients
cannot exceed 400 ft/nm and the course must intersect the runway
center line within a certain distance of the of the runway threshold,
3000-5200 ft in this instance.

The descent gradients seem OK here, so my guess would be the point of
course intersection was out of tolerance.

[[email protected]]

There are three requirements that must be met to establish straight-in
minimums:

1. Final approach course alignment with runway.

2. Descent gradient

3. Limits on where final approach course crosses or parallels the runway
centerline, extended.

Number 3 is impossible to assess without the source data.

Finally, flight inspection can nix the straight-in minimums if they don't
like the way the approach flies.

Roy Smith wrote:

> The VOR-A at New Haven
> (http://www.myairplane.com/databases/approach/pdfs/00671VG2.PDF) has an
> MDA of 720, which is about 300 feet higher than the towers in the area.
> The VOR-2
> (http://www.myairplane.com/databases/approach/pdfs/00671VG2.PDF) gets
> you down to 380, and has to deal with the same towers. Why does it get
> to have an MDA 340 feet lower than the VOR-A?
>
> In fact, the VOR-A is almost perfectly lined up with runway 32; I don't
> see why it couldn't have been the VOR-32 with an MDA about 300 feet
> lower. Any of you TERPs-heads out there understand what's going on here?

[Roy Smith]

In article >,
Greg Esres > wrote:

> <<In fact, the VOR-A is almost perfectly lined up with runway 32;>>
>
> In addition to the runway alignment issue, there are two other
> criteria used for issuing straight in minimums: descent gradients
> cannot exceed 400 ft/nm and the course must intersect the runway
> center line within a certain distance of the of the runway threshold,
> 3000-5200 ft in this instance.
>
> The descent gradients seem OK here, so my guess would be the point of
> course intersection was out of tolerance.

The FAC is based on a VOR radial; by picking a radial up or down a
couple of degrees, they can make the FAC intersect the extended
centerline anywhere they want. The approach is over water and the VOR
is on the field, so neither terrain or signal quality should be an issue
for which radial they use.

[Steven P. McNicoll]

"Andrew Sarangan" > wrote in message
...
>
> But there are straight-in approaches with the MAP well past the runway
> threshold. Look at VOR24@RID for example.
>

Interesting. One wonders why this isn't a VOR-A approach.

[Ash Wyllie]

Steven P. McNicoll opined

>"Roy Smith" > wrote in message
...
>>>
>>> Apples and oranges. You're comparing the straight-in MDA of the VOR RWY
>>> 2
>>> to the MDA of the VOR-A. The VOR-A has only a circling MDA, which is 720
>>> feet, the same as the circling MDA of the VOR RWY 2.
>>>
>>
>> Yeah, but the point of my question was, "Why didn't they publish
>> straight-in minimums for the VOR-A and call it the VOR-32?"
>>

>I don't know, I'm no TERPS expert, but I'd wager it's because the MAP is
>beyond the runway 32 threshold.

But HVN VOR-2 has a) a greater difference between the approach course and the
runway b) the same past the threshold MAP nd c) a very simular missed
prodedure.



-ash
Cthulhu for President!
Why vote for a lesser evil?

[Greg Esres]

<<they can make the FAC intersect the extended centerline anywhere
they want.>>

In theory, yes.

However, I have called Flight Procedures to ask about approaches
similar to this, and the reason was the one I gave.

There are sometimes obstacles that can be avoided by aiming the FAC
towards the center of the airport, rather than the runway itself, and
the placement of the intersection becomes limited.

Unsatisfying, I know, because of its vagueness.

[[email protected]]

VOR-20 at BAF has straight-in minimums, and I believe the MAP is well
beyond the threshold.

I don't see why the MAP location would have anything to do with
straight in vs circling.






On Sun, 31 Oct 2004 01:14:09 GMT, "Steven P. McNicoll"
>
>I don't know, I'm no TERPS expert, but I'd wager it's because the MAP is
>beyond the runway 32 threshold.
>