Tolerances - Published Minimum Altitudes

If assigned IFR altitudes can be considered to have a tolerance of +/-
200 ft before you are "busted", what applies to published minimum
altitudes other than DH and MDA on approach plates? Most people will
say that you are not supposed to descend any amount below the DH/MDA
altitudes. Does this also apply to procedure turn altitudes,
transitions etc.? Is there a tolerance that is in effect +200 -0 that
applies?

In practical terms, whereas a decent of 100 ft below an assigned
altitude will cause no problems, is such a decent of 50-100' below a
published procedure turn altitude, transition altitude enough to get in
trouble?

John

John,

Not really answering your question, but note that descending below DH is (by
definition if you think about it) legal even if you see absolutely nothing.
MDA means don't go below this altitude, but DH means make you decision here
and immediately start to get 'er going up which implies some time spent
below DH.

Hilton


"John" wrote in message
...
If assigned IFR altitudes can be considered to have a tolerance of +/- 200
ft before you are "busted", what applies to published minimum altitudes
other than DH and MDA on approach plates? Most people will say that you
are not supposed to descend any amount below the DH/MDA altitudes. Does
this also apply to procedure turn altitudes, transitions etc.? Is there a
tolerance that is in effect +200 -0 that applies?

In practical terms, whereas a decent of 100 ft below an assigned altitude
will cause no problems, is such a decent of 50-100' below a published
procedure turn altitude, transition altitude enough to get in trouble?

John

John writes:
If assigned IFR altitudes can be considered to have a tolerance of +/-
200 ft before you are "busted", what applies to published minimum
altitudes other than DH and MDA on approach plates? Most people will
say that you are not supposed to descend any amount below the DH/MDA
altitudes. Does this also apply to procedure turn altitudes,
transitions etc.? Is there a tolerance that is in effect +200 -0 that
applies?

In practical terms, whereas a decent of 100 ft below an assigned
altitude will cause no problems, is such a decent of 50-100' below a
published procedure turn altitude, transition altitude enough to get in
trouble?

[It's "descent", not "decent".]

The question for which I've never seen a definitive
answer is where is the reference point on the airplane
for measuring the altitude to which the MDA/DH applies?
It would seem that on the largest transport aircraft,
the cockpit would be at a substantially higher altitude
than the wheels on an approach. The wheels could all
but be on the ground while the cockpit is at 50 feet.
Visibility for the pilot is the controlling factor.
If a radar altimeter is the instrument determining
altitude for a low DH, is its reading compensated for
the aircraft attitude?

John wrote:
If assigned IFR altitudes can be considered to have a tolerance of +/-
200 ft before you are "busted", what applies to published minimum
altitudes other than DH and MDA on approach plates? Most people will
say that you are not supposed to descend any amount below the DH/MDA
altitudes. Does this also apply to procedure turn altitudes,
transitions etc.? Is there a tolerance that is in effect +200 -0 that
applies?

In practical terms, whereas a decent of 100 ft below an assigned
altitude will cause no problems, is such a decent of 50-100' below a
published procedure turn altitude, transition altitude enough to get in
trouble?

John

The practical test standards are simply wrong when it comes to MEAs or
any minimum altitude on an IAP.

The minimum is the minimum by law...period.

The only exception is not really an exception at all, DA. As a matter
of regulation DA does not have the word "minimum" associated with it.
Instead, at DA the decision must be made to continue descent with visual
reference or begin the missed approach.

Sam Spade wrote:
John wrote:
If assigned IFR altitudes can be considered to have a tolerance of +/-
200 ft before you are "busted", what applies to published minimum
altitudes other than DH and MDA on approach plates? Most people will
say that you are not supposed to descend any amount below the DH/MDA
altitudes. Does this also apply to procedure turn altitudes,
transitions etc.? Is there a tolerance that is in effect +200 -0 that
applies?

In practical terms, whereas a decent of 100 ft below an assigned
altitude will cause no problems, is such a decent of 50-100' below a
published procedure turn altitude, transition altitude enough to get
in trouble?

John

The practical test standards are simply wrong when it comes to MEAs or
any minimum altitude on an IAP.

The minimum is the minimum by law...period.

The only exception is not really an exception at all, DA. As a matter
of regulation DA does not have the word "minimum" associated with it.
Instead, at DA the decision must be made to continue descent with visual
reference or begin the missed approach.

This is in line with what I thought from a strictly legalistic
standpoint. But in practical real world terms, does this mean that if
you are hand flying an approach and say are in a procedure turn, you
will fly 100' above the published altitude to avoid going below? Or do
most ppl just fly the published altitude (I'm talking transition or PT
or something other than "close to the ground") and not worry about +/-
100 ft?

John

John wrote:

Sam Spade wrote:

John wrote:

If assigned IFR altitudes can be considered to have a tolerance of
+/- 200 ft before you are "busted", what applies to published minimum
altitudes other than DH and MDA on approach plates? Most people will
say that you are not supposed to descend any amount below the DH/MDA
altitudes. Does this also apply to procedure turn altitudes,
transitions etc.? Is there a tolerance that is in effect +200 -0
that applies?

In practical terms, whereas a decent of 100 ft below an assigned
altitude will cause no problems, is such a decent of 50-100' below a
published procedure turn altitude, transition altitude enough to get
in trouble?

John


The practical test standards are simply wrong when it comes to MEAs or
any minimum altitude on an IAP.

The minimum is the minimum by law...period.

The only exception is not really an exception at all, DA. As a matter
of regulation DA does not have the word "minimum" associated with it.
Instead, at DA the decision must be made to continue descent with
visual reference or begin the missed approach.


This is in line with what I thought from a strictly legalistic
standpoint. But in practical real world terms, does this mean that if
you are hand flying an approach and say are in a procedure turn, you
will fly 100' above the published altitude to avoid going below? Or do
most ppl just fly the published altitude (I'm talking transition or PT
or something other than "close to the ground") and not worry about +/-
100 ft?

John

I wouldn't worry about the regulation until passing the IF, where
obstacle clearance becomes 500 feet (perhaps less because of temperature
or other altimeter errors).

The PTS limits MDA to +100 feet, - zero feet, which is very important at
that point.

On May 9, 11:03 pm, John wrote:
If assigned IFR altitudes can be considered to have a tolerance of +/-
200 ft before you are "busted", what applies to published minimum
altitudes other than DH and MDA on approach plates? Most people will
say that you are not supposed to descend any amount below the DH/MDA
altitudes. Does this also apply to procedure turn altitudes,
transitions etc.? Is there a tolerance that is in effect +200 -0 that
applies?

In practical terms, whereas a decent of 100 ft below an assigned
altitude will cause no problems, is such a decent of 50-100' below a
published procedure turn altitude, transition altitude enough to get in
trouble?

John

Where is the +/-200ft tolerance specified except in the PTS? I've
heard many people refer to it, but could not find it in the FAR or AIM.

Andrew Sarangan wrote:
On May 9, 11:03 pm, John wrote:

If assigned IFR altitudes can be considered to have a tolerance of +/-
200 ft before you are "busted", what applies to published minimum
altitudes other than DH and MDA on approach plates? Most people will
say that you are not supposed to descend any amount below the DH/MDA
altitudes. Does this also apply to procedure turn altitudes,
transitions etc.? Is there a tolerance that is in effect +200 -0 that
applies?

In practical terms, whereas a decent of 100 ft below an assigned
altitude will cause no problems, is such a decent of 50-100' below a
published procedure turn altitude, transition altitude enough to get in
trouble?

John


Where is the +/-200ft tolerance specified except in the PTS? I've
heard many people refer to it, but could not find it in the FAR or AIM.

It isn't.

I am currently working through the King Schools IFR DVDs in
preparation for my US IFR written. Something is really bugging me,
and I figured someone here might know the answer.... (And I am too
impatient to wait for my next lesson.)

In one section of this course, we learn that the outer merker and
middle marker used to matter. It used to be the case that if they
were broken you had to increase your approach minimums by some amount.
But the King's don't think we have to know why your minimums used to
change, how the rule about minimums changed (other than getting
abolished), or why the rule changed -- simply that it no longer
matters any more, and you must know that since some FAA questions will
try to "trick" you by giving you the old rules (which I don't know
anyways) as potential answers.

They then go and devote a whole section of the course to suitable
substitutions for the broken devices. So now I know that if I want to
ignore the outer marker on an ILS, and it happens to be broken, it is
legal for me to substitute an NDB and ignore that instead.

So my question is twofold:

a) are marker beacons used for any real (regulatory) purpose any more,
or are they simply for positional awareness?

b) if the answer to (a) is "no, they are no longer used", why do we
have to memorize a set of rules about what we can legally substitute
for these unused beacons?

Chris

"SUMMARY: The FAA is amending its regulations to reflect technological
advances that support area navigation (RNAV); include provisions on the use
of suitable RNAV systems for navigation; amend certain terms for consistency
with those of the International Civil Aviation Organization (ICAO); remove
reference to the middle marker in certain sections because a middle marker
is no longer operationally required; clarify airspace terminology; and
incorporate by reference obstacle departure procedures into Federal
regulations. The changes will facilitate the use of new navigation reference
sources, enable advancements in technology, and increase efficiency of the
National Airspace System."

The bottom line answer to your question is that the test writers in Oklahoma
City have always been several years behind the times. Take a knowledge test
today and you will be faced with black-and-white weather maps that require
diligent searching to find on the ADDS page...the color graphics that we use
every day have not yet been recognized by the test writers.

Bob Gardner


"Christopher Brian Colohan" wrote in message
.. .
I am currently working through the King Schools IFR DVDs in
preparation for my US IFR written. Something is really bugging me,
and I figured someone here might know the answer.... (And I am too
impatient to wait for my next lesson.)

In one section of this course, we learn that the outer merker and
middle marker used to matter. It used to be the case that if they
were broken you had to increase your approach minimums by some amount.
But the King's don't think we have to know why your minimums used to
change, how the rule about minimums changed (other than getting
abolished), or why the rule changed -- simply that it no longer
matters any more, and you must know that since some FAA questions will
try to "trick" you by giving you the old rules (which I don't know
anyways) as potential answers.

They then go and devote a whole section of the course to suitable
substitutions for the broken devices. So now I know that if I want to
ignore the outer marker on an ILS, and it happens to be broken, it is
legal for me to substitute an NDB and ignore that instead.

So my question is twofold:

a) are marker beacons used for any real (regulatory) purpose any more,
or are they simply for positional awareness?

b) if the answer to (a) is "no, they are no longer used", why do we
have to memorize a set of rules about what we can legally substitute
for these unused beacons?

Chris