I know the aim para 5.4.7 says that aircraft approach categories are
based on 1.3 times the stall speed in the landing config at max
certificated gross landing weight (comes from far 97.3 (b).

However I know I have read somewhere, perhaps the aim or a far,
something along the lines that where the manufacturer has provided
data to allow the pilot to determined the approach speed based on
weight, that this can then be used to determine which category the
aircraft falls in.

Does anyone know of where I would have read something along these
lines?

Stan

On Sat, 18 Dec 2004 17:49:42 GMT, wrote:

>I know the aim para 5.4.7 says that aircraft approach categories are
>based on 1.3 times the stall speed in the landing config at max
>certificated gross landing weight (comes from far 97.3 (b).
>
>However I know I have read somewhere, perhaps the aim or a far,
>something along the lines that where the manufacturer has provided
>data to allow the pilot to determined the approach speed based on
>weight, that this can then be used to determine which category the
>aircraft falls in.
>
>Does anyone know of where I would have read something along these
>lines?
>
>Stan

Perhaps:

14 CFR 97.3

(b) Aircraft approach category means a grouping of aircraft based on a
speed of VREF, if specified, or if VREF is not specified, 1.3 VS0 at the
maximum certificated landing weight. VREF, VS0, and the maximum
certificated landing weight are those values as established for the
aircraft by the certification authority of the country of registry. The
categories are as follows: ...


--ron

"Ron Rosenfeld" > wrote in message =
...
> On Sat, 18 Dec 2004 17:49:42 GMT, wrote:
>=20
>>I know the aim para 5.4.7 says that aircraft approach categories are
>>based on 1.3 times the stall speed in the landing config at max
>>certificated gross landing weight (comes from far 97.3 (b).
>>
>>However I know I have read somewhere, perhaps the aim or a far,
>>something along the lines that where the manufacturer has provided
>>data to allow the pilot to determined the approach speed based on
>>weight, that this can then be used to determine which category the
>>aircraft falls in.
>>
>>Does anyone know of where I would have read something along these
>>lines?
>>
>>Stan
>=20
> Perhaps:
>=20
> 14 CFR 97.3
>=20
> (b) Aircraft approach category means a grouping of aircraft based on a
> speed of VREF, if specified, or if VREF is not specified, 1.3 VS0 at =
the
> maximum certificated landing weight. VREF, VS0, and the maximum
> certificated landing weight are those values as established for the
> aircraft by the certification authority of the country of registry. =
The
> categories are as follows: ...
>=20
> --ron

Stan:
Continuing beyond what Ron quoted, here's more...
"If it is necessary to maneuver at speeds in excess of the upper limit
of a speed range for a category, the minimums for the next higher
category should be used."

I don't know why it says "should". I'd expect it to say "must".
Anyway, that applies to me. I like to approach with several extra =
knots,
which bumps me into category B.

I think your question was related to the calculation of Vref for the
specific landing weight and conditions, as is done when operating
heavier, usually turbine-powered, aircraft.

In article >,
John R. Copeland > wrote:
>> (b) Aircraft approach category means a grouping of aircraft based on a
>> speed of VREF, if specified, or if VREF is not specified, 1.3 VS0 at the
>
>Continuing beyond what Ron quoted, here's more...
>"If it is necessary to maneuver at speeds in excess of the upper limit
>of a speed range for a category, the minimums for the next higher
>category should be used."

I never understood why they bothered to specify a "book" speed for
approach category when the real rule is that it's based on the speed
that you fly during the approach.

--
Ben Jackson
>
http://www.ben.com/

"Ben Jackson" > wrote in message =
news:YL5xd.284746$R05.189455@attbi_s53...
>=20
> I never understood why they bothered to specify a "book" speed for
> approach category when the real rule is that it's based on the speed
> that you fly during the approach.
>=20
> --=20
> Ben Jackson
>
The reason is based in aerodynamics.
1.3 Vs0 is an acceptable approximation to the point of maximum
lift/drag ratio of fixed-wing airfoils on typical small =
general-aviation aircraft.
That makes it a reasonable target for threshold-crossing speed.

In article >,
John R. Copeland > wrote:
>The reason is based in aerodynamics.
>1.3 Vs0 is an acceptable approximation to the point of maximum
> lift/drag ratio of fixed-wing airfoils on typical small
>general-aviation aircraft.
>That makes it a reasonable target for threshold-crossing speed.

Sure, but the rule doesn't need a number, much less a formula. The rule
is effectively "approach class is based on the speed you fly the approach".

--
Ben Jackson
>
http://www.ben.com/

<<I don't know why it says "should". I'd expect it to say "must".>>

Because wherever you got that isn't a regulatory document. Your
source must be either the Pilot/Controller Glossary or the Instrument
Flying Handbook. Ron quoted the regulation.

On Sun, 19 Dec 2004 02:33:28 GMT, (Ben Jackson) wrote:

>I never understood why they bothered to specify a "book" speed for
>approach category when the real rule is that it's based on the speed
>that you fly during the approach.

At one time, the bump in approach category based on speed flying the
approach only applied to circling approaches.


--ron

Thanks Ron. My old aim/far does not have the same wording. this is
exactly what I was looking for.
Since on most jets, Vref is specified by the manufacturer based on
weight, then at near minimum flight weight, vref may be 118 kts, cat
B. But at some higher weight, vref may be 125 kts, cat C. Hence this
** regulation ** allows that the aircraft category be determined
based on present weight, and not maximum certified weight.
And so the quandary is, why would the aim para 5.4.7 be saying that
category is based on speed at ** max certified landing weight ** ?

Ron Rosenfeld > wrote:

>On Sat, 18 Dec 2004 17:49:42 GMT, wrote:
>
>>I know the aim para 5.4.7 says that aircraft approach categories are
>>based on 1.3 times the stall speed in the landing config at max
>>certificated gross landing weight (comes from far 97.3 (b).

>
>14 CFR 97.3
>
> (b) Aircraft approach category means a grouping of aircraft based on a
>speed of VREF, if specified, or if VREF is not specified, 1.3 VS0 at the
>maximum certificated landing weight. VREF, VS0, and the maximum
>certificated landing weight are those values as established for the
>aircraft by the certification authority of the country of registry.
>--ron

On Sun, 19 Dec 2004 15:57:55 GMT, wrote:

>why would the aim para 5.4.7 be saying that
>category is based on speed at ** max certified landing weight **

Probably your AIM is old, also:

http://www.faa.gov/ATpubs/AIM/Chap5/aim0504.html#5-4-7

5-4-7. Instrument Approach Procedures

a. Aircraft approach category means a grouping of aircraft based on a
speed of VREF, if specified, or if VREF not specified, 1.3 VSO at the
maximum certificated landing weight. ...


--ron

Thanks Ron. Where I had thought "max cert weight v ref" always
governed, its nice to see the category can be based actual landing
speeds, where specified.
stan

On Sun, 19 Dec 2004 13:48:15 -0500, Ron Rosenfeld
> wrote:

>On Sun, 19 Dec 2004 15:57:55 GMT, wrote:
>
>>why would the aim para 5.4.7 be saying that
>>category is based on speed at ** max certified landing weight **
>
>Probably your AIM is old, also:
>
>http://www.faa.gov/ATpubs/AIM/Chap5/aim0504.html#5-4-7
>
>5-4-7. Instrument Approach Procedures
>
> a. Aircraft approach category means a grouping of aircraft based on a
>speed of VREF, if specified, or if VREF not specified, 1.3 VSO at the
>maximum certificated landing weight. ...
>
>
>--ron