How wide is an NDB approach course?

What is the protected area under an NDB approach course? Since the
course guidance is cruder than an ILS, I'd expect it would be wider, but
how much wider? I ask also in the context of when I should consider
myself "established" on course (for purposes of descent).

Jose
--
He who laughs, lasts.
for Email, make the obvious change in the address.

On Tue, 16 Jan 2007 21:28:12 GMT, Jose
wrote:

What is the protected area under an NDB approach course? Since the
course guidance is cruder than an ILS, I'd expect it would be wider, but
how much wider? I ask also in the context of when I should consider
myself "established" on course (for purposes of descent).

Jose

When within 10 degrees of the published course.

When within 10 degrees of the published [NDB approach] course.

Thanks. I take it the course is then 20 degrees wide, with some lesser
protected area on the outskirts.

Jose
--
He who laughs, lasts.
for Email, make the obvious change in the address.

Just ran across this (from Instrument Procedures Handbook, FAA-H-8261-1,
page 4-6):
------
The International Civil Aviation Organization (ICAO) definition of
established is considered as being within half full scale deflection
for the ILS and VOR, or within +/- 5 degrees of the required bearing
for the nondirectional radio beacon (NDB).
------


Andrey


Jose wrote:
When within 10 degrees of the published [NDB approach] course.

Thanks. I take it the course is then 20 degrees wide, with some lesser
protected area on the outskirts.

Jose

Just ran across this (from Instrument Procedures Handbook, FAA-H-8261-1,
page 4-6):
------
The International Civil Aviation Organization (ICAO) definition of
established is considered as being within half full scale deflection
for the ILS and VOR, or within +/- 5 degrees of the required bearing
for the nondirectional radio beacon (NDB).

Thanks. That's very intersting and helpful.

Jose
--
Humans are pack animals. Above all things, they have a deep need to
follow something, be it a leader, a creed, or a mob. Whosoever fully
understands this holds the world in his hands.
for Email, make the obvious change in the address.

Bill Zaleski wrote:
On Tue, 16 Jan 2007 21:28:12 GMT, Jose
wrote:


What is the protected area under an NDB approach course? Since the
course guidance is cruder than an ILS, I'd expect it would be wider, but
how much wider? I ask also in the context of when I should consider
myself "established" on course (for purposes of descent).

Jose


When within 10 degrees of the published course.

There is no policy or rule to support that.

On Tue, 16 Jan 2007 16:50:04 -0800, Sam Spade
wrote:

Bill Zaleski wrote:
On Tue, 16 Jan 2007 21:28:12 GMT, Jose
wrote:


What is the protected area under an NDB approach course? Since the
course guidance is cruder than an ILS, I'd expect it would be wider, but
how much wider? I ask also in the context of when I should consider
myself "established" on course (for purposes of descent).

Jose


When within 10 degrees of the published course.

There is no policy or rule to support that.

He asked when he should consider himself established for the purpose
of descent. Have you got better guideline to follow when in a cockpit
looking at an instrument panel? In the absence of policy or rules, as
you say, what do you suggest a better answer would be?

Bill Zaleski wrote:
On Tue, 16 Jan 2007 16:50:04 -0800, Sam Spade
wrote:


Bill Zaleski wrote:

On Tue, 16 Jan 2007 21:28:12 GMT, Jose
wrote:



What is the protected area under an NDB approach course? Since the
course guidance is cruder than an ILS, I'd expect it would be wider, but
how much wider? I ask also in the context of when I should consider
myself "established" on course (for purposes of descent).

Jose


When within 10 degrees of the published course.


There is no policy or rule to support that.


He asked when he should consider himself established for the purpose
of descent. Have you got better guideline to follow when in a cockpit
looking at an instrument panel? In the absence of policy or rules, as
you say, what do you suggest a better answer would be?


When the bearing indicates on-course. 10 degrees is way too early.

[You're established inbound on an NDB]
When within 10 degrees of the published course.
There is no policy or rule to support that.

Taking Sam Spade's TERPs quote,

The primary area is longitudinally centered on the FAC, and is 10 miles long. The primary area is 2.5 miles wide at the facility, and expands uniformly to 6 miles wide at 10 miles from the facility.

I draw a little diagram, and find that the angle along the outside of
the primary area to be atan(((6/2)-(2.5/2))/10) = atan(7/40) = 10
degrees. So, ten degrees from the facility puts me 2.5 miles inside the
protected area. Sounds good to me. Start on down.

Jose
--
He who laughs, lasts.
for Email, make the obvious change in the address.

So, ten degrees from the facility puts me 2.5 miles inside the protected area.

Oops. 2.5/2 miles, or 1.25 miles inside the protected area. Pesky twos!

Jose
--
He who laughs, lasts.
for Email, make the obvious change in the address.