VOR approach- when to descend from the FAF

Greg Esres wrote:
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.

Correct. The protected airspace for a VOR IAP overhead the VOR when
it's the FAF is 1 mile each side of the station. This width expands as
the aircraft departs the VOR/FAF. The maximum course change permitted
at the VOR/FAF is 30 degrees.

Descent shouldn't be made unless the pilot is tracking on course inbound
to the VOR/FAF. If he is on course as station passage occurs, and a
course change is required, a turn to intercept while commencing descent
is expected in the design of the criteria; i.e., the descent gradient is
calculated from the VOR/FAF, not from some imaginary post-facility point
of intercept, and the maneuver required to reintercept is minimal
assumming reasonable comptetency.

"Terence Wilson" wrote in message
...
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.

I spend that minute or so making sure my heading and approach airspeed are
under control, and then simply catch up to the descent afterward when the
needle comes back. It'll be interesting to see how other people do it, but
that's the way I was trained.

-c

On 02/21/08 09:27, gatt wrote:
"Terence Wilson" wrote in message
...
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.

I spend that minute or so making sure my heading and approach airspeed are
under control, and then simply catch up to the descent afterward when the
needle comes back. It'll be interesting to see how other people do it, but
that's the way I was trained.

-c



I was taught to begin the descent at station passage (using the 5 'T's).
It's never taken more than just a very few seconds for the CDI to start
coming back in. A minute seems awfully long.

By the way, if the needle doesn't come back in, I would go missed. The
first thing I do there is begin a climb. I really don't see how it causes
any problems to begin the descent at station passage (assuming that is
what the procedure calls for, of course).


--
Mark Hansen, PP-ASEL, Instrument Airplane, USUA Ultralight Pilot
Cal Aggie Flying Farmers
Sacramento, CA

"Mark Hansen" wrote in message
...

I spend that minute or so making sure my heading and approach airspeed
are
under control, and then simply catch up to the descent afterward when the
needle comes back. It'll be interesting to see how other people do it,
but
that's the way I was trained.

I was taught to begin the descent at station passage (using the 5 'T's).
It's never taken more than just a very few seconds for the CDI to start
coming back in. A minute seems awfully long.

Yeah, I was just throwing that out as a ballpark figure. It shouldn't take
very long at all, which means it's even less of a problem to catch up to the
descent afterward.

I prefer to have the altitude under me rather than above me throughout the
approach, but, at that point it's not like you're going to fly into anything
if you're 50 feet lower immediately after crossing the station than if you
waited. Or, you have bigger issues.

If I were taking the IFR checkride, though, I'd definately hold the altitude
until I could demonstrate to the examiner that I had recaptured the CDI was
100% established. That's the kind of thing my examiner would have expected
and how I was taught to do it. (caveat: Since they almost always use the
examiner, they teach to his specific expectations, which may be a factor.)

-c
CP-ASEL-IA

On Thu, 21 Feb 2008 09:27:00 -0800, "gatt"
wrote:


"Terence Wilson" wrote in message
.. .
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.

I spend that minute or so making sure my heading and approach airspeed are
under control, and then simply catch up to the descent afterward when the
needle comes back. It'll be interesting to see how other people do it, but
that's the way I was trained.

-c


Trained well, in my opinion.

That's exactly the way to do it, IMHO.