How wide is an NDB approach course?

Jim Carter wrote:

-----Original Message-----
From: Sam Spade ]
Posted At: Saturday, January 20, 2007 6:46 PM
Posted To: rec.aviation.ifr
Conversation: How wide is an NDB approach course?
Subject: How wide is an NDB approach course?


...

With an RMI you might be somewhere in town. With a fixed card you

might

not even be in the same county.


Come on now Sam, you know that's not right. NDB approaches are safe and
accurate when properly executed by trained and current pilots. They have
been for years. I will grant that they take a lot more situational
awareness than letting the GPS steer the bird down the tracks, but even
so the NDB approach still works just fine.


NDB always worked fine in my airline's simulators. My meager experience
with them on the line was from fair to poor.

Our former cold war enemies, the Soviets, make them work by
lock-stepping one NDB on the tail and one on the nose. With RMIs and
two ADFs, that did work.

Had the USAF crew that died along with Secretary Brown understood that
concept, they all would be alive today.

Jim Carter wrote:



I realize a lot of the responses are written in humor, but lest some of
the younger readers get the wrong impression - it is still possible to
properly execute an NDB approach and safely arrive if the weather is
above published minimums. Hundreds of pilots flew LF range and NDB
approaches for many years without killing themselves or their
passengers.


Most of the NDB IAPs flown by airlines was with slaved RMI/ADF
indicators. Those approaches became seldom used by the major carriers
by the early 1960s.

-----Original Message-----
From: Sam Spade ]
Posted At: Sunday, January 21, 2007 7:32 AM
Posted To: rec.aviation.ifr
Conversation: How wide is an NDB approach course?
Subject: How wide is an NDB approach course?

....
Most of the NDB IAPs flown by airlines was with slaved RMI/ADF
indicators. Those approaches became seldom used by the major carriers
by the early 1960s.

All of my experience has been 91, 135, and 141 so I defer to those with
121 experience for that topic.

NDBs (we still called them ADFs) were still in wide use for Wichita iron
back in the early '70s and that is where my exposure started. We flew
NDB approaches quite frequently in the mid-west and plain states because
ILS was only available at major metropolitan centers and VOR was only
available at a few remote airports (like Gage, Oklahoma). There were
frequently other fields around, but there were no pub'd VOR approaches
for a lot of them so we had to use NDB.

Those approaches work just as well today as they did 35 years ago, but I
will grant you that they take more work and more diligence to execute
properly. NDB approaches are definitely not my first choice unless there
is some young pup in the right seat who's been bustin' my balls about
being an ancient aviator. Then an NDB approach can be a real humbling
experience with a good wind and maybe a few static discharges off in the
distance.

BTW, old Frontier pilots probably still have nightmares about all the
NDBs they had to fly because of all the little farm towns they serviced.

Jim Carter wrote:



BTW, old Frontier pilots probably still have nightmares about all the
NDBs they had to fly because of all the little farm towns they serviced.


Yes, that is why I mentioned majors. A friend of mine who flew with the
old North Central flew ADF approaches all the time. Then again, it was
in flat country.

You're right, the old Frontier had a lot of mountains without the dual
beacon setup in Eastern Europe.

I didn't know that. Thanks for the info!

Andrey


Jake Brodsky wrote:

the day. However at night, because the ionospheric absorption goes down
and because the signal can skip, the FCC requires most stations to dial
their power back and change antenna patterns.

Andrey Serbinenko wrote:
I didn't know that. Thanks for the info!

Andrey


Jake Brodsky wrote:

the day. However at night, because the ionospheric absorption goes down
and because the signal can skip, the FCC requires most stations to dial
their power back and change antenna patterns.

That's why pilots use different HF frequencies at night over the ocean.

Michael wrote:

Sam Spade wrote:

When within 10 degrees of the published course.

There is no policy or rule to support that.


Yeah, the FAA is so incredibly disfunctional that it is literally
possible to have a 'properly' (meaning in accordance with TERPS)
designed approach flown 'correctly' (meaning to the level required to
pass the instrument rating ride as per the PTS) with functional
(meaning working well enough to pass the mandated operational checks)
equipment, and still slam yourself into something.

Check out the LVJ VOR-B.

Michael


What's wrong with that approach, at least until leaving MDA?

If you're referring to the snake pit below MDA when circle-to-land only
minima are published, this one is a comparative cakewalk compared to the
high HAA circling MDAs in the mountains.

Bill Zaleski wrote:

On Wed, 17 Jan 2007 19:38:04 +0000, Peter
wrote:


Bill Zaleski wrote


When within 10 degrees of the published course.

That's not a lot, since NDBs can be anything up to 30 degrees off,
IME. My local one certainly can be; it's on a coast (SHM at EGKA). But
that IAP is also DME-based.


An NDB is to a shotgun, as an ILS is to a rife with a scope. It's a
let down to an area of probability at a safe, conservative altitude.


If the NDB is on the nose, I would agree. If it is on the tail,
however, and the MAP is near the max distance limites, it is a crap
shoot whether you will remain in the primary area of protected airspace.

Sam Spade wrote:
What's wrong with that approach, at least until leaving MDA?

The 1200 ft tower that you can hit. It's located outside the trapezium
that defines the protected areas (inner and outer) but your VOR
receiver can be within 4 degrees of perfect (the more restrictive
standard for the VOR check - some COR checks allow 6 degrees) and your
needle need not exceed 3/4 scale deflection (the more restrictive
standard on the instrument airplane PTS - you are allowed full scale on
the partial panel approach) to put you right into the tower.

Michael

Michael wrote:
Sam Spade wrote:

What's wrong with that approach, at least until leaving MDA?


The 1200 ft tower that you can hit. It's located outside the trapezium
that defines the protected areas (inner and outer) but your VOR
receiver can be within 4 degrees of perfect (the more restrictive
standard for the VOR check - some COR checks allow 6 degrees) and your
needle need not exceed 3/4 scale deflection (the more restrictive
standard on the instrument airplane PTS - you are allowed full scale on
the partial panel approach) to put you right into the tower.

Michael


No doubt it is pushing the criteria, although the criteria would permit
a MAP as much as approximately 5 miles further.

The real issue here is a simplistic flight test standard that is written
in terms of an on-airport VOR or one within 5 or 10 miles of the airport.

When you are flying an IAP away from a VOR station and the FAF is 20 to
25 miles out, with the final going out further, you had darn well have
the CDI centered or at least touching the centered doughnot. A sharp
CFI who understands all that would not accept PTS minimum performance on
a extreme distance VOR approach.