Ping Sam Spade: DA versus DH on an ILS?

On 2/28/2007 10:11:34 AM, Sam Spade wrote:

Peter R. wrote:


Sorta like the transistion from SID to DP....




You mean SID to DP to SID in FAA-land. ;-)

Ah, sheesh... I didn't realize they are going back to SIDs. Just when you
think you have this stuff down.

--
Peter

FAA-H-8261-1
page 5-18

DA is currently used on RNAV approach charts with vertical descent guidance.
DA will replace DH for Category I precision IAPs. MDA and DA are referenced
to MSL and measured with a barometric altimeter. CAT II and III approach DHs
are referenced to AGL and measured with a radio altimeter.

Gordy wrote:

FAA-H-8261-1
page 5-18

DA is currently used on RNAV approach charts with vertical descent guidance.
DA will replace DH for Category I precision IAPs. MDA and DA are referenced
to MSL and measured with a barometric altimeter. CAT II and III approach DHs
are referenced to AGL and measured with a radio altimeter.




CAT II is DH/DA. Unrestricted CAT III Is Alert Height, measure in MSL.
Radar altitude is not used as a determination of Alert Height.

DA/DH is used in restricted CAT III operations.

On 2/28/2007 10:38:03 AM, "Gordy" wrote:

FAA-H-8261-1
page 5-18

DA is currently used on RNAV approach charts with vertical descent guidance.
DA will replace DH for Category I precision IAPs. MDA and DA are referenced
to MSL and measured with a barometric altimeter. CAT II and III approach DHs
are referenced to AGL and measured with a radio altimeter.

Hmmm, I just looked at the online Instrument Procedures Handbook at page 5-18
and don't see that quote the

http://www.faa.gov/library/manuals/a...ures_handbook/

I even searched the entire chapter for a string from your quote and didn't
run across it. What am I missing? Are you quoting from a paper copy? If so,
is it one to a few years older?

--
Peter

The publication used was from 2004, FAA-H-8261-1. I was not aware it has
been updated.
The new FAA-H-8261-1A publication is dated 2007. I need buy the new version.


"Peter R." wrote in message
...
On 2/28/2007 10:38:03 AM, "Gordy" wrote:

FAA-H-8261-1
page 5-18

DA is currently used on RNAV approach charts with vertical descent
guidance.
DA will replace DH for Category I precision IAPs. MDA and DA are
referenced
to MSL and measured with a barometric altimeter. CAT II and III approach
DHs
are referenced to AGL and measured with a radio altimeter.

Hmmm, I just looked at the online Instrument Procedures Handbook at page
5-18
and don't see that quote the

http://www.faa.gov/library/manuals/a...ures_handbook/

I even searched the entire chapter for a string from your quote and didn't
run across it. What am I missing? Are you quoting from a paper copy? If
so,
is it one to a few years older?

--
Peter

Peter R. wrote:
On 2/28/2007 10:38:03 AM, "Gordy" wrote:


FAA-H-8261-1
page 5-18

DA is currently used on RNAV approach charts with vertical descent guidance.
DA will replace DH for Category I precision IAPs. MDA and DA are referenced
to MSL and measured with a barometric altimeter. CAT II and III approach DHs
are referenced to AGL and measured with a radio altimeter.


Hmmm, I just looked at the online Instrument Procedures Handbook at page 5-18
and don't see that quote the

http://www.faa.gov/library/manuals/a...ures_handbook/

I even searched the entire chapter for a string from your quote and didn't
run across it. What am I missing? Are you quoting from a paper copy? If so,
is it one to a few years older?



It is the

MINIMUM DESCENT ALTITUDE,DECISION ALTITUDE,AND DECISION HEIGHTDAis
currently used on RNAV approach chart swith vertical descent guidance.
DAwill replace DHfor Category I precision IAPs. MDAand DA are referenced
to MSL and measured with a barometric altimeter. CATII and III approach
DHs are referenced to AGL and measured with a radio altimeter.

And, it is just plain wrong as to CAT III. It is misleading as to CAT
II because CAT II DA/DH is expressed in both MSL (Da/DA) and AGL for RA
(at RA site).

The new 1A publication contains the same information. Chapter 5, page 18.

MINIMUM DESCENT ALTITUDE, DECISION ALTITUDE,

AND DECISION HEIGHT

MDA and DA are referenced to MSL and measured

with a barometric altimeter. CAT II and III

approach DHs are referenced to AGL and measured

with a radio altimeter.

"Gordy" wrote in message
...
FAA-H-8261-1
page 5-18

DA is currently used on RNAV approach charts with vertical descent
guidance. DA will replace DH for Category I precision IAPs. MDA and DA are
referenced to MSL and measured with a barometric altimeter. CAT II and III
approach DHs are referenced to AGL and measured with a radio altimeter.

On 2/28/2007 11:22:50 AM, "Gordy" wrote:

The publication used was from 2004, FAA-H-8261-1. I was not aware it has
been updated.
The new FAA-H-8261-1A publication is dated 2007. I need buy the new version.

I guess I do, too.

Thanks for the information, although as Sam pointed out, some needs to be
taken with a grain of salt. Considering that I will most likely never fly a
CAT II or CAT III approach, it is not that big a deal.

--
Peter

Gordy wrote:

The new 1A publication contains the same information. Chapter 5, page 18.

MINIMUM DESCENT ALTITUDE, DECISION ALTITUDE,

AND DECISION HEIGHT

MDA and DA are referenced to MSL and measured

with a barometric altimeter. CAT II and III

approach DHs are referenced to AGL and measured

with a radio altimeter.

"Gordy" wrote in message
...

FAA-H-8261-1
page 5-18

DA is currently used on RNAV approach charts with vertical descent
guidance. DA will replace DH for Category I precision IAPs. MDA and DA are
referenced to MSL and measured with a barometric altimeter. CAT II and III
approach DHs are referenced to AGL and measured with a radio altimeter.



I guess they didn't do much of a review. ;-)

You will not see me flying any CAT II or III approaches either.

One of my instrument instructors had me land while under the hood. It
started out as a no gyro approach simulation and continued to a full stop
landing. It is really hard not to peek when you are descending at 100/200
feet per minute on the gauges and making small corrections as directed by
your instructor. I'm not sure how much help he gave me, he said none, but I
can guarantee he was hanging on.

"Peter R." wrote in message
...
On 2/28/2007 11:22:50 AM, "Gordy" wrote:

The publication used was from 2004, FAA-H-8261-1. I was not aware it has
been updated.
The new FAA-H-8261-1A publication is dated 2007. I need buy the new
version.

I guess I do, too.

Thanks for the information, although as Sam pointed out, some needs to be
taken with a grain of salt. Considering that I will most likely never fly
a
CAT II or CAT III approach, it is not that big a deal.

--
Peter