Intercepting the ILS

Roy Smith wrote:

wrote:

Yesterday I was out getting an IPC. We were doing the Stockton, CA
ILS. ATC had us intercepting the localizer at 2000 feet. The
altitude for glideslope interception is 1800 ( underlined ).
[...]
The new CFII criticized this procedure and told me that the plate
specified 1800, and it was wrong to intercept at 2000.


I can't see any reason not to intercept at 2000. I think your new guy
is full of it.

As a matter of regulation, the G/S is to be used as primary vertical
guidance only from the PFAF inbound. There are some places, where early
use of the G/S has resulted in airspace violations, LAX being the most
notable.

In the case cited, the CFI is nitpicking but is nonetheless legally correct.

wrote:
Roy Smith wrote:

wrote:

Yesterday I was out getting an IPC. We were doing the Stockton, CA
ILS. ATC had us intercepting the localizer at 2000 feet. The
altitude for glideslope interception is 1800 ( underlined ).
[...]
The new CFII criticized this procedure and told me that the plate
specified 1800, and it was wrong to intercept at 2000.


I can't see any reason not to intercept at 2000. I think your new guy
is full of it.

As a matter of regulation, the G/S is to be used as primary vertical
guidance only from the PFAF inbound. There are some places, where early
use of the G/S has resulted in airspace violations, LAX being the most
notable.

Let's be argumentative here. What regulation are you referring to?
In the case of LAX (the Civet 4 arrival I quoted earlier), the
problem was that following the glideslope caused the airplane to
violate published crossing restrictions.

In the case cited, the CFI is nitpicking but is nonetheless legally correct.

At SCK there was no crossing restriction either given in the
clearance or published. The pilot is free to descend *at his
discretion* from 2000 to 1800. Following the glideslope is a perfectly
acceptable way of doing that. The CFI is not only nit-picking, but in
this instance is wrong. Not only that, but he's making additional
unnecessary work.

wrote:

wrote:

Roy Smith wrote:



Let's be argumentative here. What regulation are you referring to?
In the case of LAX (the Civet 4 arrival I quoted earlier), the
problem was that following the glideslope caused the airplane to
violate published crossing restrictions.

In the Los Angeles case the violations occurred inside the CIVET
arrival, actually on the ILS profile. Those fixes are issued under Part
97 just as it the legal point at which the G/S *controls* for
descent(the PFAF).

In the case cited, the CFI is nitpicking but is nonetheless legally correct.


At SCK there was no crossing restriction either given in the
clearance or published. The pilot is free to descend *at his
discretion* from 2000 to 1800. Following the glideslope is a perfectly
acceptable way of doing that. The CFI is not only nit-picking, but in
this instance is wrong. Not only that, but he's making additional
unnecessary work.


I agree that the CFI is procedurally wrong, although legally correct.
Let me put it another way: the CFI is stuck on one aspect of the issue,
the other being that the pilot can make certain elections so long as he
does not use the G/S as primary for descent prior to the PFAF. The CFI
has a duty to teach resonable procedure while pointing out the legal
nuances of when the G/S is primary for altitude control. It sounds like
he covered only one aspect of the issue, which while correct legally, is
incorrect and out of context procedurally.

On Thu, 26 Jan 2006 09:29:10 -0800, wrote:



As a matter of regulation, the G/S is to be used as primary vertical
guidance only from the PFAF inbound. There are some places, where early
use of the G/S has resulted in airspace violations, LAX being the most
notable.

In the case cited, the CFI is nitpicking but is nonetheless legally correct.

Huh? What regulation?

Published guidance in the AIM indicates that the GS is generally usable out
to ten miles, but this may be extended at certain locations.




Ron (EPM) (N5843Q, Mooney M20E) (CP, ASEL, ASES, IA)

wrote:


As a matter of regulation, the G/S is to be used as primary vertical
guidance only from the PFAF inbound. There are some places, where early
use of the G/S has resulted in airspace violations, LAX being the most
notable.

In the case cited, the CFI is nitpicking but is nonetheless legally
correct.

Tim,

Can you give an example of how an airspace violation could occur? It
seems that as long as the pilot doesn't descend below the minimum
altitude published for the segment of the approach he's in, then
descending on the glidepath can't put the aircraft any lower than
dropping down immediately to the minimum segment altitude at the
beginning of the segment. If he's in the Intermediate, then the
glidepath will more than likely keep him higher than dropping down to
the minimum altitude due to the length of the intermediate normally
compensating for the required altitude loss at 150 ft per mile optimum.
If the airspace violation would be from the aircraft being too high,
then perhaps the procedure should have a maximum altitude shown or the
controller issue a crossing restriction.
The glideslope intercept altitude is a minimum altitude, not a mandatory
or maximum altitude. From a TERPS standpoint there's no problem with
descending on the glideslope from 2000 on the procedure in question
instead of 1800.
If the pilot uses the glideslope for backup vertical guidance to give a
smooth transition to the final segment (while using the altimeter
readout outside the FAF to ensure he doesn't descend below 1800) then
what's wrong with that?

JPH

JPH wrote:

Can you give an example of how an airspace violation could occur? It
seems that as long as the pilot doesn't descend below the minimum
altitude published for the segment of the approach he's in, then
descending on the glidepath can't put the aircraft any lower than
dropping down immediately to the minimum segment altitude at the
beginning of the segment. If he's in the Intermediate, then the
glidepath will more than likely keep him higher than dropping down to
the minimum altitude due to the length of the intermediate normally
compensating for the required altitude loss at 150 ft per mile optimum.
If the airspace violation would be from the aircraft being too high,
then perhaps the procedure should have a maximum altitude shown or the
controller issue a crossing restriction.

It's happen at LAX quite a few times when the air is hot and the
underlying Ontario airspace rises to provide less than 1,000 feet of
vertical on the LAX G/Ses. The G/S doesn't move.

The glideslope intercept altitude is a minimum altitude, not a mandatory
or maximum altitude. From a TERPS standpoint there's no problem with
descending on the glideslope from 2000 on the procedure in question
instead of 1800.

True enough, and if the pilot wants to remain above the G/S that is
perfectly legal. But, any charted minimum stepdown altitudes prior to
the PFAF are governing, not the G/S.

If the pilot uses the glideslope for backup vertical guidance to give a
smooth transition to the final segment (while using the altimeter
readout outside the FAF to ensure he doesn't descend below 1800) then
what's wrong with that?

Nothing wrong with that.

If the pilot uses the glideslope for backup vertical guidance to give a
smooth transition to the final segment (while using the altimeter
readout outside the FAF to ensure he doesn't descend below 1800) then
what's wrong with that?

Nothing wrong with that.

That isn't really correct either. There's no necessity to monitor
the altimeter at SCK because there's no step-down fixes or other
crossing restrictions at issue. Above 1800 feet on the glideslope, the
glideslope is advisory, but the pilot is perforce satisfying the =1800
foot minimum altitude requirement. Below 1800 feet the glideslope
becomes primary. So in practical terms nothing happens at 1800 feet.
There's nothing to monitor. (OK. I know, you part 121 types have now
reached a point where the weather can below minimums without
necessitating a miss.)

At *Stockton* (the subject of the question), there is no legal issue.
At LAX on the Civet arrival, and other situations where there are
step-down altitudes on the localizer outside the PFAF, there is a
potential issue. The step down minima take precedence over the GS
altitude.

The altitude at the marker is a double check on the
altimeter and the glide slope. If the altimeter is set
incorrectly or broken or if you have intercepted the wrong
glide slope lobe, the pilot has an opportunity to catch the
error and figure out what is wrong.


--
James H. Macklin
ATP,CFI,A&P

--
The people think the Constitution protects their rights;
But government sees it as an obstacle to be overcome.
some support
http://www.usdoj.gov/olc/secondamendment2.htm
See http://www.fija.org/ more about your rights and duties.


wrote in message
oups.com...
| If the pilot uses the glideslope for backup vertical
guidance to give a
| smooth transition to the final segment (while using the
altimeter
| readout outside the FAF to ensure he doesn't descend
below 1800) then
| what's wrong with that?
|
| Nothing wrong with that.
|
| That isn't really correct either. There's no necessity
to monitor
| the altimeter at SCK because there's no step-down fixes or
other
| crossing restrictions at issue. Above 1800 feet on the
glideslope, the
| glideslope is advisory, but the pilot is perforce
satisfying the =1800
| foot minimum altitude requirement. Below 1800 feet the
glideslope
| becomes primary. So in practical terms nothing happens at
1800 feet.
| There's nothing to monitor. (OK. I know, you part 121
types have now
| reached a point where the weather can below minimums
without
| necessitating a miss.)
|
| At *Stockton* (the subject of the question), there is no
legal issue.
| At LAX on the Civet arrival, and other situations where
there are
| step-down altitudes on the localizer outside the PFAF,
there is a
| potential issue. The step down minima take precedence over
the GS
| altitude.
|

The altitude at the marker is a double check on the
altimeter and the glide slope. If the altimeter is set
incorrectly or broken or if you have intercepted the wrong
glide slope lobe, the pilot has an opportunity to catch the
error and figure out what is wrong.

That is of course true - but it's a different altitude, 1758 in this
case. It's the 1800 altiitude that loses significance once the GS has
been intercepted.

BTW, the chances of following the wrong lobe of the GS to the FAF
without noticing a problem is close to nil. It either has reverse
sensing or requires ridiculous rates of descent.

wrote:
If the pilot uses the glideslope for backup vertical guidance to give a
smooth transition to the final segment (while using the altimeter
readout outside the FAF to ensure he doesn't descend below 1800) then
what's wrong with that?


Nothing wrong with that.


That isn't really correct either. There's no necessity to monitor
the altimeter at SCK because there's no step-down fixes or other
crossing restrictions at issue. Above 1800 feet on the glideslope, the
glideslope is advisory, but the pilot is perforce satisfying the =1800
foot minimum altitude requirement. Below 1800 feet the glideslope
becomes primary. So in practical terms nothing happens at 1800 feet.
There's nothing to monitor. (OK. I know, you part 121 types have now
reached a point where the weather can below minimums without
necessitating a miss.)

At *Stockton* (the subject of the question), there is no legal issue.
At LAX on the Civet arrival, and other situations where there are
step-down altitudes on the localizer outside the PFAF, there is a
potential issue. The step down minima take precedence over the GS
altitude.

We are procedurally in violent agreement. Nonetheless, the G/S is not
primary prior to the PFAF, any minimum altitude constraints
notwithstanding. That is the legalese of Part 97. I am just the messenger.