VOR approach- when to descend from the FAF

On Sat, 16 Feb 2008 18:56:05 -0800, Terence Wilson
wrote:

When flying a VOR approach in which the FAF is defined by the VOR, is
it appropriate to start the descent to the MAP, or next stepdown,
immediately after overflying the VOR or should I wait until I have
positive course guidance for the final approach segment?

I ask because it can sometimes take 1-2nm for the CDI to move, which
may require a rushed descent to the MAP on some approaches.

Good question. Yes you may. Don't have the aim or far in front of
me, but I've always waited for first positive indication of the FROM
indicator. You do not need pos course guidance to start descent.

On Feb 17, 7:00*am, wrote:
On Sat, 16 Feb 2008 18:56:05 -0800, Terence Wilson
wrote:

When flying a VOR approach in which the FAF is defined by the VOR, is
it appropriate to start the descent to the MAP, or next stepdown,
immediately after overflying the VOR or should I wait until I have
positive course guidance for the final approach segment?

I ask because it can sometimes take 1-2nm for the CDI to move, which
may require a rushed descent to the MAP on some approaches.

Good question. * Yes you may. *Don't have the aim or far in front of
me,

You do if you're online. Just Google "Aeronautical Information
Manual" or "CFRs". (I don't find that information in those documents,
however. But perhaps I didn't look in the right places.)

but I've always waited for first positive indication of the FROM
indicator. *You do not need pos course guidance to start descent.

pstanley wrote:

You do not need pos course guidance to start descent.

Such a statement needs documentation, IMO.

On Tue, 19 Feb 2008 08:07:11 -0800 (PST), Greg Esres
wrote:

pstanley wrote:

You do not need pos course guidance to start descent.

Such a statement needs documentation, IMO.





This is being treated like some kind of academic
angels-on-the-head-of-a-pin question. It is not.

Stuff happens. I have seen enough "competent" pilots screw up a
course intercept to know that it doesn't take all that much for a
pilot to end up well below the FAF altitude with no positive course
guidance, if he starts his descent with none. Distractions can mount
up in a hurry, and one can find himself in a situation with a high
pucker factor in a hurry. Few pilots who find themselves in this
situation then take the proper corrective action, in my experience.
They usually "try harder" to reintercept the course while going still
lower. This practially always ends up in a situation that could be
disastrous in actual conditions.

Advising someone new to instrument flying that it is an OK thing to
start a descent with no positive course guidance is a really bad
thing, in my opinion, and I base that opinion on watching a lot of
pilots, many of them experienced and instrument rated, screw
approaches up pretty badly, for any number of reasons.

I don't care what the "book" says.

Les Izmore wrote:

This is being treated like some kind of academic angels-on-the-head-
of-a-pin question. It is not.

Not to you, maybe. People ask questions here for a variety of
reasons: 1) legality, 2) safety, 3) passing checkrides, 4) curiosity,
etc.

Regarding safety, no doubt you're 100% correct.

We have a local VOR approach with a course change at the FAF and a
high descent gradient on final. Without descending immediately pass
the VOR, the odds of getting in shrink rapidly.

Greg Esres wrote:

Les Izmore wrote:

This is being treated like some kind of academic angels-on-the-head-
of-a-pin question. It is not.

Not to you, maybe. People ask questions here for a variety of
reasons: 1) legality, 2) safety, 3) passing checkrides, 4) curiosity,
etc.

Regarding safety, no doubt you're 100% correct.

We have a local VOR approach with a course change at the FAF and a
high descent gradient on final. Without descending immediately pass
the VOR, the odds of getting in shrink rapidly.

Not to mention real issues trying to do a slam-dunk low to the ground.

On Feb 19, 2:53*pm, Les Izmore wrote:

This is being treated like some kind of academic
angels-on-the-head-of-a-pin question. *It is not.

It is academic.

Two choices, very simple. Either you are on the final approach
course, or not. If not, you go missed, nothing complicated.

They usually "try harder" *to reintercept the course while going still
lower. *This practially always ends up in a situation that could be
disastrous in actual conditions.

Then that pilot is behind the plane. See above for choices of
action. Really very academic. It may not be a training issue, but a
currency issue, thus the IMPORTANCE of staying current.

and I base that opinion on watching a lot of
pilots, many of them experienced and *instrument rated, screw
approaches up pretty badly, for any number of reasons.

At anytime a pilot "screws up" as you alleged, missed is always that
option. Very academic. I personally experience quite the opposite
for IA pilots when I was their safety pilot, they get it right and
never gone full deflection. I am not a CFI by any means for what this
is worth.

I don't care what the "book" says.

Book is very clear. If you are not on the final approach course
within the established tolerances, you go missed. What part of the
book is hard to understand?

The orignal question is a very elementary question for IA flying.

For what it's worth, in my 600 hours of instrument flying, it takes a
hell of a lot more then 1 or 2 miles for the CDI to start moving. If
that is happening to the original poster, or you experienced that,
then there is something wrong with that station signal or airplane
equipment and a missed approach is in order. KMBO has the VOR alpha
approach and I can pick up the VOR signal strong on both my NAV1 and
NAV2 within 20 miles.

When you are within 1 or 2 miles of a final approach fix (I.E. VOR) it
is normal to get a full deflection from that "zone of confusion" for
the CDI. The needles will recapture within a mile or two of station
passage.

But you do not descend before getting the from flag on your NAV1 or
NAV2 AND being on the final approach course. If you don't get a from
flag you go missed even if you are on the final approach course as
something is radically wrong equipment wise.. Note the word AND, both
being on the approach course AND from flag, BOTH must be present.
VERY SIMPLE!

The original question was so basic, that it sounded like an Mx
question..

Allen

On Wed, 20 Feb 2008 05:41:20 -0800 (PST), "
wrote:

On Feb 19, 2:53*pm, Les Izmore wrote:

This is being treated like some kind of academic
angels-on-the-head-of-a-pin question. *It is not.

It is academic.

Two choices, very simple. Either you are on the final approach
course, or not. If not, you go missed, nothing complicated.


I think you need to go back and re-read the original post.


They usually "try harder" *to reintercept the course while going still
lower. *This practially always ends up in a situation that could be
disastrous in actual conditions.

Then that pilot is behind the plane. See above for choices of
action. Really very academic. It may not be a training issue, but a
currency issue, thus the IMPORTANCE of staying current.

and I base that opinion on watching a lot of
pilots, many of them experienced and *instrument rated, screw
approaches up pretty badly, for any number of reasons.

At anytime a pilot "screws up" as you alleged, missed is always that
option. Very academic. I personally experience quite the opposite
for IA pilots when I was their safety pilot, they get it right and
never gone full deflection. I am not a CFI by any means for what this
is worth.

I don't care what the "book" says.

Book is very clear. If you are not on the final approach course
within the established tolerances, you go missed. What part of the
book is hard to understand?

The orignal question is a very elementary question for IA flying.

For what it's worth, in my 600 hours of instrument flying, it takes a
hell of a lot more then 1 or 2 miles for the CDI to start moving. If
that is happening to the original poster, or you experienced that,
then there is something wrong with that station signal or airplane
equipment and a missed approach is in order. KMBO has the VOR alpha
approach and I can pick up the VOR signal strong on both my NAV1 and
NAV2 within 20 miles.

When you are within 1 or 2 miles of a final approach fix (I.E. VOR) it
is normal to get a full deflection from that "zone of confusion" for
the CDI. The needles will recapture within a mile or two of station
passage.

But you do not descend before getting the from flag on your NAV1 or
NAV2 AND being on the final approach course. If you don't get a from
flag you go missed even if you are on the final approach course as
something is radically wrong equipment wise.. Note the word AND, both
being on the approach course AND from flag, BOTH must be present.
VERY SIMPLE!

The original question was so basic, that it sounded like an Mx
question..

Allen

For you folks voting to go missed if the CDI remains fully deflected
when passing the FAF...

I hope you mean that you will proceed to the missed approach fix and
then go missed. Initiating a missed approach early is not advised
because
obstacle clearance is not guarenteed per the AIM:

"...Reasonable buffers are provided for normal maneuvers. However, no
consideration is given to an abnormally early turn. Therefore, when an
early missed approach is executed, pilots should, unless otherwise
cleared by ATC, fly the IAP as specified on the approach plate to the
missed approach point at or above the MDA or DH before executing a
turning maneuver."
(5.4.21b)


wrote:
On Feb 19, 2:53�pm, Les Izmore wrote:

This is being treated like some kind of academic
angels-on-the-head-of-a-pin question. �It is not.

It is academic.

Two choices, very simple. Either you are on the final approach
course, or not. If not, you go missed, nothing complicated.

They usually "try harder" �to reintercept the course while going still
lower. �This practially always ends up in a situation that could be
disastrous in actual conditions.

Then that pilot is behind the plane. See above for choices of
action. Really very academic. It may not be a training issue, but a
currency issue, thus the IMPORTANCE of staying current.

and I base that opinion on watching a lot of
pilots, many of them experienced and �instrument rated, screw
approaches up pretty badly, for any number of reasons.

At anytime a pilot "screws up" as you alleged, missed is always that
option. Very academic. I personally experience quite the opposite
for IA pilots when I was their safety pilot, they get it right and
never gone full deflection. I am not a CFI by any means for what this
is worth.

I don't care what the "book" says.

Book is very clear. If you are not on the final approach course
within the established tolerances, you go missed. What part of the
book is hard to understand?

The orignal question is a very elementary question for IA flying.

For what it's worth, in my 600 hours of instrument flying, it takes a
hell of a lot more then 1 or 2 miles for the CDI to start moving. If
that is happening to the original poster, or you experienced that,
then there is something wrong with that station signal or airplane
equipment and a missed approach is in order. KMBO has the VOR alpha
approach and I can pick up the VOR signal strong on both my NAV1 and
NAV2 within 20 miles.

When you are within 1 or 2 miles of a final approach fix (I.E. VOR) it
is normal to get a full deflection from that "zone of confusion" for
the CDI. The needles will recapture within a mile or two of station
passage.

But you do not descend before getting the from flag on your NAV1 or
NAV2 AND being on the final approach course. If you don't get a from
flag you go missed even if you are on the final approach course as
something is radically wrong equipment wise.. Note the word AND, both
being on the approach course AND from flag, BOTH must be present.
VERY SIMPLE!

The original question was so basic, that it sounded like an Mx
question..

Allen

Peter wrote:
For what this is worth, on the European IR one is not supposed to
descend (from the platform altitude) unless one is established within
5 degrees of the track. I don't know the reference but this is what I
was always taught. To me, it makes sense and the only time I would
deviate from it would be


ICAO standards for "established" are 1/2 scale deflection. The US
doesn't have a similar definition, unfortunately. Sam Spade was
arguing that, over the VOR, that standard doesn't have much meaning.
For a staying-in-protected-airspace point of view, I'm sure he's
correct.