FAR Part 97: Aircraft Approach Categories - IAS vs Ground Speed

I'm an Instrument Airplane student, and am having a disagreement
with my instructor on one topic - that of Aircraft Approach Categories.

According to 14 CFR Part 97.3 (b), it provides the speed ranges for
the different aircraft categories (A-E). In all the documentation I've
read, this "speed" is the IAS of the airplane.

However, my CFI says that this is based on the Ground Speed. When
we are flying an approach with a tail wind and can see that, although
we are remaining below 90kts IAS, our Ground Speed (shown by the GPS unit)
is just over 90kts, he said I must use the category B minimums.

I understand his reasoning (in that the faster we're moving across
the ground, the faster we'll move out of the protection zone, etc.),
but from what I can find, the FAR doesn't mention ground speed at all.

If I use the minimums associated with the higher of the IAS or
Ground Speed, would I get dinged during a proficiency check?

The reason I ask is that I've been asked questions before where the
examiner was trying to make sure that I completely understood the
rule, and I'm worried that selecting minimums that are higher than
necessary will show that I don't really understand it.

Thanks,

--
Mark Hansen, PP-ASEL, Instrument Student
Sacramento, CA

You are correct. There is no end to what some flight instructors will dream
up or invent. Everything the FAA does in the world of charting is predicated
on IAS.

Mark Hansen wrote:

I'm an Instrument Airplane student, and am having a disagreement
with my instructor on one topic - that of Aircraft Approach Categories.

According to 14 CFR Part 97.3 (b), it provides the speed ranges for
the different aircraft categories (A-E). In all the documentation I've
read, this "speed" is the IAS of the airplane.

However, my CFI says that this is based on the Ground Speed. When
we are flying an approach with a tail wind and can see that, although
we are remaining below 90kts IAS, our Ground Speed (shown by the GPS unit)
is just over 90kts, he said I must use the category B minimums.

I understand his reasoning (in that the faster we're moving across
the ground, the faster we'll move out of the protection zone, etc.),
but from what I can find, the FAR doesn't mention ground speed at all.

If I use the minimums associated with the higher of the IAS or
Ground Speed, would I get dinged during a proficiency check?

The reason I ask is that I've been asked questions before where the
examiner was trying to make sure that I completely understood the
rule, and I'm worried that selecting minimums that are higher than
necessary will show that I don't really understand it.

Thanks,

--
Mark Hansen, PP-ASEL, Instrument Student
Sacramento, CA

In article , wrote:
You are correct. There is no end to what some flight instructors will dream
up or invent. Everything the FAA does in the world of charting is predicated
on IAS.

The one exception would be the FAF-MAP timing chart for non-precision
approaches. That's groundspeed. Perhaps that's what got the
instructor confused.

On 7/15/2005 11:11, Roy Smith wrote:

In article , wrote:
You are correct. There is no end to what some flight instructors will dream
up or invent. Everything the FAA does in the world of charting is predicated
on IAS.

The one exception would be the FAF-MAP timing chart for non-precision
approaches. That's groundspeed. Perhaps that's what got the
instructor confused.

No. He made it clear that he was talking about the approach categories
as they apply to the minimums, and not about the timiming from FAF to
MAP.

--
Mark Hansen, PP-ASEL, Instrument Student
Sacramento, CA

Roy Smith wrote:

In article , wrote:
You are correct. There is no end to what some flight instructors will dream
up or invent. Everything the FAA does in the world of charting is predicated
on IAS.

The one exception would be the FAF-MAP timing chart for non-precision
approaches. That's groundspeed. Perhaps that's what got the
instructor confused.

The FAA doesn't provide timing tables in the source. The chart makers do those.
Those are still indicated airspeed. If you choose to convert those values to TAS,
then to G/S, that is your option and is a good operating practice. But, it is not
mandatory, at least not in the sense that courses and altitudes on an IAP chart
are mandatory.

wrote:


The FAA doesn't provide timing tables in the source. The chart makers do those.
Those are still indicated airspeed. If you choose to convert those values to TAS,
then to G/S, that is your option and is a good operating practice. But, it is not
mandatory, at least not in the sense that courses and altitudes on an IAP chart
are mandatory.

I meant to say if you choose to use those values as G/S and do the necessary
conversions from IAS to TAS to G/S, that is your option and a good operating practice.

wrote in message ...

I meant to say if you choose to use those values as G/S and do the
necessary
conversions from IAS to TAS to G/S, that is your option and a good
operating practice.


Those values are expressed in ground speed already, converting them to
anything else would be a bad operating practice.

wrote in message ...

The FAA doesn't provide timing tables in the source. The chart makers do
those.
Those are still indicated airspeed. If you choose to convert those values
to TAS,
then to G/S, that is your option and is a good operating practice. But,
it is not
mandatory, at least not in the sense that courses and altitudes on an IAP
chart
are mandatory.


The FAA is a chart maker, the speeds in the timing tables on FAA charts are
ground speed.

"Steven P. McNicoll" wrote:

wrote in message ...

The FAA doesn't provide timing tables in the source. The chart makers do
those.
Those are still indicated airspeed. If you choose to convert those values
to TAS,
then to G/S, that is your option and is a good operating practice. But,
it is not
mandatory, at least not in the sense that courses and altitudes on an IAP
chart
are mandatory.


The FAA is a chart maker, the speeds in the timing tables on FAA charts are
ground speed.

And, your reference that the speeds on NACO charts are ground speeds?

wrote in message ...

You are correct. There is no end to what some flight instructors will
dream
up or invent. Everything the FAA does in the world of charting is
predicated
on IAS.


Not quite everything. The approach timing table uses ground speed.