Skystar
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Aircraft Performance Categories - A, B, C, D

Mon Dec 10, 2001 1:51 pm

Does anyone know what are the definitions for the aircraft performance categories, eg. Cat A, B, C & D?

I often see these on approach charts, etc, but don't actually know the definitions for such categories. Basically I look at airliners in Cat C & D.

What are the requirements to meet particular categories, etc?

Cheers,

Justin
 
Ralgha
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RE: Aircraft Performance Categories - A, B, C, D

Mon Dec 10, 2001 3:41 pm

Technically they're not preformance categories, they're approach categories.

Catagory A = Speed less than 91 knots
Catagory B = Speed >= 91 and less than 121 knots
Catagory C = Speed >= 121 and less than 141 knots
Catagory D = Speed >= 141 and less than 166 knots
Catagory E = Speed >= 166 knots (only includes certain military aircraft)

The speeds are speeds used for the final visual portion of the approach (straight in or circle to land). An airplane will only fall into one catagory at any one time, but might not always be in that catagory depending on various factors governing the maneuvering speeds of the airplane during this portion of the approach.

The approach catagory of an aircraft determines the minimums that will be used for the approach.

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PW4084
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RE: Aircraft Performance Categories - A, B, C, D

Mon Dec 10, 2001 4:40 pm

To augment what Ralgha said, the speeds he listed are based upon 1.3 times the stalling speed of the airplane in the landing configuration at maximum certificated landing weight (1.3VSO in civilian parlance). Reference 14 CFR 97.3

PW4084
 
Skystar
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RE: Aircraft Performance Categories - A, B, C, D

Tue Dec 11, 2001 8:46 am

Thanks for your responses.

Cheers,

Justin
 
SAAFNAV
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RE: Aircraft Performance Categories - A, B, C, D

Mon Jun 11, 2012 1:28 pm

Sorry to bring up this old thread.

Having a discussion at work about the Descend Rates for IFR for different Categories of aircraft.

E.g. Cat B 804fpm and 655fpm on the outbound and inbound legs respectively.

Where can I find the regulations for this?

Regards,
Erich
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Mir
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RE: Aircraft Performance Categories - A, B, C, D

Mon Jun 11, 2012 8:49 pm

Quoting saafnav (Reply 4):

Any more specifics you can provide? It's true that as your approach speed goes up, your descent rate will have to as well in order to maintain a certain glidepath angle. But I've never heard of any blanket regulations on that, nor have I heard of differences in outbound and inbound legs. There might be certain approaches that require a certain descent rate, though.

-Mir
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smartt1982
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RE: Aircraft Performance Categories - A, B, C, D

Mon Jun 11, 2012 9:36 pm

Is the reason a Boeing 737-800 is normally CAT 3 but for a 1x engine circling it becomes a CAT D. Is this because of the change of circling speed (is this simply the speed the aircraft fly’s the circling manoeuvre?) or another factor?
 
Mir
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RE: Aircraft Performance Categories - A, B, C, D

Tue Jun 12, 2012 12:36 am

Quoting smartt1982 (Reply 6):
Is this because of the change of circling speed (is this simply the speed the aircraft fly’s the circling manoeuvre?)

Yup. Not that I'd be very eager to circle in a single-engine situation, particularly to the point where Cat C vs. Cat D would make a difference. Then again, European circling radii are much larger than those in the US - 1.7 miles (Cat C) isn't all that much, even when you've got everything working.

-Mir
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SAAFNAV
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RE: Aircraft Performance Categories - A, B, C, D

Tue Jun 12, 2012 4:29 am

I think it is the 'shuttle rates'.
When I was on course I remember studying it for the C47TP.

Maybe under the heading of Maximum Theoretical Descend Rate?
I know for a Cat C aircraft it should be 1 197fpm on the outbound and 755fpm on the inbound leg of the letdown procedure, but can't find anything to prove it.

Regards,
Erich
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zeke
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RE: Aircraft Performance Categories - A, B, C, D

Tue Jun 12, 2012 6:12 pm

Quoting saafnav (Reply 4):
E.g. Cat B 804fpm and 655fpm on the outbound and inbound legs respectively.

Where can I find the regulations for this?

That is only for reversals or racetracks, it comes from Table I-4-3-1 in PAN OPS 8168 Vol2

Outbound track
Cat A/B 804 ft/min (245 m/min)
Cat C/D/E/H 1197 ft/min (365 m/min)

Inbound track

Cat A/B maximum 655 ft/min (200 m/min), minimum 394 ft/min (120 m/min)
Cat H 755 ft/min (230 m/min)
Cat C/D/E 1000 ft/min (305 m/min), minimum 590 ft/min (180 m/min)

The maximum descent gradients for the intermediate segment is done with the procedure design, they can go as high as 13.2 % if the speed is kept below 90 kts. The final segment depends on the type of approach, and if it has a FAF or not.

Quoting Mir (Reply 7):
Then again, European circling radii are much larger than those in the US

You mean the FAA TERPS standard is more restrictive than the international ICAO standard.

Quoting saafnav (Reply 8):
I know for a Cat C aircraft it should be 1 197fpm on the outbound and 755fpm on the inbound leg of the letdown procedure, but can't find anything to prove it.

Close, 1197/1000 ft/min or 365/305 is for Cat C. Your numbers would work for a CH47 (Cat H), but not for a C47TP (Cat A).
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SAAFNAV
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RE: Aircraft Performance Categories - A, B, C, D

Tue Jun 12, 2012 6:43 pm

Thanks, this is exactly what I was looking for.

Sorry for the misconfusion, was talking about the C47TP and then actually referred to the C-130 without saying so. She's a Cat C.

I appreciate the help.

Erich
On-board Direction Consultant
 
FJATP
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RE: Aircraft Performance Categories - A, B, C, D

Wed Apr 01, 2015 8:47 am

Hi Guys

My first post on the forum as I found this topic whilst doing a google search.

I am posting this just in case anybody does what I did and confuses the two different types of information.

I have copied below the frequent confusion between classes and categories, take a look:

We have Aeroplane PERFORMANCE CLASSES -

CLASS A (multi-engine JETs and some Turboprops( > 5700kg or > 9 seats)
CLASS B (small propellor)
CLASS C (large reciprocating engine -propellor)

Then we have Aeroplane Approach CATEGORIES (by approach speed)

A Less than 91 kt
B From 91 to 120 kt
C From 121 to 140 kt
D From 141 to 165 kt
E From 166 to 210 kt

(Taken from Bristol Ground School Forum)

Regards

FJATP

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