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

Mark,

It's pretty clear that your instructor is mistaken, as you have
cited chapter and verse of the pertinent regulatory article.

This also agrees with the FAA's Instrument Flying Handbook,
publication faa-h-8083, pages 8-23 and 8-24, in which the approach
category speeds are based on being 1.3 times the stall speed of the
aircraft in the landing configuration at gross weight. Stall speeds are
never predicated on ground speed. The error in doing so should be
readily apparent.

If your instructor is basing his instruction and recommendation on
"ground speed" then challenge him to show you chapter and verse where
ground speed is the acceptable determining factor. Your ground speed
comes into play on instrument approaces in timing the approach and in
determining your rate of descent for a given glidepath angle. Your
instructor, while well intentioned appears to be "reading too much into
the situation". Using a lower category than authorized can result in a
bust of minimums. Using a higher category than required can result in
not being able to take full advantage of lower minimums.

It would behoove you at this point to also read and know not only
the instrument PTS, but also the FAA Instrument Flying handbook as well
as whatever texts your instructor is using for your ground based
instruction.

Good Luck
Dave

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,

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.

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.

And so it is (almost - I seem to recall it's really CAS, but that
wouldn't make much difference). That's the regulation.

However, my CFI says that this is based on the Ground Speed.

It's hard to prove a negative, so I can't say there is NO regulatory
support for what he says, but I've certainly never seen it. Have you
asked him to show you where he read this? Further, without RNAV that
works at low altitudes or DME on the approach (which isn't rare but is
far from universal), ground speed is an estimate - and these rules are
a lot older than widespread use of RNAV that works at low altitudes.

In other words - I think your CFI is totally wrong on this one.

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.

Well, yes, it will. Only I think you understand it fine; it's your
instructor who is steering you wrong.

There are situations where it makes sense to select higher minimums on
an approach (especially a circling approach) where the higher speed
makes remaining within the protected area for the lower mins
problematic. I certainly don't think it would be wrong to say "Yes, I
know that technically cat A mins apply, but I am going to use Cat B
mins because the wind conditions make remaining within the Cat A
protected area problematic." If the situation is a circling approach
with restrictions imposed and very high winds that would require an
excessive bank angle to remain within the protected area, he would
probably consider that a sign of good judgment. But you should be
clear that this is something you are choosing to do because it makes
sense, and that the regulations do permit lower mins.

Michael

"Mark Hansen" wrote in message
...

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.


I think your instructor is confusing the approach category speeds with the
timing table speeds, which 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.

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

On 7/15/2005 11:10, Dave S wrote:

Mark,

It's pretty clear that your instructor is mistaken, as you have
cited chapter and verse of the pertinent regulatory article.

This also agrees with the FAA's Instrument Flying Handbook,
publication faa-h-8083, pages 8-23 and 8-24, in which the approach
category speeds are based on being 1.3 times the stall speed of the
aircraft in the landing configuration at gross weight. Stall speeds are
never predicated on ground speed. The error in doing so should be
readily apparent.

If your instructor is basing his instruction and recommendation on
"ground speed" then challenge him to show you chapter and verse where
ground speed is the acceptable determining factor. Your ground speed
comes into play on instrument approaces in timing the approach and in
determining your rate of descent for a given glidepath angle. Your
instructor, while well intentioned appears to be "reading too much into
the situation". Using a lower category than authorized can result in a
bust of minimums. Using a higher category than required can result in
not being able to take full advantage of lower minimums.

It would behoove you at this point to also read and know not only
the instrument PTS, but also the FAA Instrument Flying handbook as well
as whatever texts your instructor is using for your ground based
instruction.

Thank you. I have gone through the Instrument Flying Handbook (as well
as the Instrument Procedures Handbook, and others...). Although I haven't
yet gone through the PTS, it is on my list of things to get to.



Good Luck
Dave

On 7/15/2005 11:12, Michael wrote:

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.

And so it is (almost - I seem to recall it's really CAS, but that
wouldn't make much difference). That's the regulation.

However, my CFI says that this is based on the Ground Speed.

It's hard to prove a negative, so I can't say there is NO regulatory
support for what he says, but I've certainly never seen it. Have you
asked him to show you where he read this? Further, without RNAV that
works at low altitudes or DME on the approach (which isn't rare but is
far from universal), ground speed is an estimate - and these rules are
a lot older than widespread use of RNAV that works at low altitudes.

In other words - I think your CFI is totally wrong on this one.

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.

Well, yes, it will. Only I think you understand it fine; it's your
instructor who is steering you wrong.

There are situations where it makes sense to select higher minimums on
an approach (especially a circling approach) where the higher speed
makes remaining within the protected area for the lower mins
problematic. I certainly don't think it would be wrong to say "Yes, I
know that technically cat A mins apply, but I am going to use Cat B
mins because the wind conditions make remaining within the Cat A
protected area problematic." If the situation is a circling approach
with restrictions imposed and very high winds that would require an
excessive bank angle to remain within the protected area, he would
probably consider that a sign of good judgment. But you should be
clear that this is something you are choosing to do because it makes
sense, and that the regulations do permit lower mins.

Thank you Michael. This is how I've been looking at it (but I didn't
express it very well).

When I've asked my CFI to show me the regs, he basically says that it
makes sense to use the higher mins, and I haven't pushed it. This isn't
the first time we've disagreed on the Regs. In another case, he claimed
that it was illegal to fly IFR without a flight plan and ATC clearance,
but that rule applies only to Controlled airspace.

I think I won't bother pushing it, as I'm clear on the concept, and
don't really need to head-but the CFI over it ;-)


Michael



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