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enilria
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Class 3 Aircraft And Class 4 Aircraft

Tue Jan 12, 2010 4:14 pm

Does anybody know the width requirements for each of these classes? Also, are any aircraft in danger of moving from Class 3 to 4 with the addition of modern winglets? I know a 757-200 is Class 4 and a 737-700 is Class 3. I don't know much else...anybody have a link?
 
arffdude
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RE: Class 3 Aircraft And Class 4 Aircraft

Tue Jan 12, 2010 4:40 pm

Aircraft wingspans fall into six different design groups, which are as follows:

Group I - < 49'
Group 2 - 49'-78'
Group 3 - 79'-117'
Group 4 - 118'-170'
Group 5 - 171'-213'
Group 6 - 214'-262'

Aircraft can also be arranged in order of approach speeds, which are labeled as A through E, with E being the highest. Every airport has an Airport Reference Code, which is the design group plus the approach speed category of the most demanding aircraft it is expected to handle. Most small/medium size airports for example fall into Airport Reference Code CIII.

While design groups measure aircraft wingspans, aircraft lengths also fall into five categories that determine the ARFF index of an airport, which specifies minimum firefighting equipment and agent that an airport must have on hand.
 
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enilria
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RE: Class 3 Aircraft And Class 4 Aircraft

Tue Jan 12, 2010 4:47 pm

Quoting ARFFdude (Reply 1):
Aircraft wingspans fall into six different design groups, which are as follows:


Just what I needed! I added you to my resp list. Happen to know if any are so close to Type 4 that winglet mods are putting them over the line?

[Edited 2010-01-12 08:48:42 by enilria]
 
BMI727
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RE: Class 3 Aircraft And Class 4 Aircraft

Tue Jan 12, 2010 4:59 pm



Quoting Enilria (Reply 2):
Happen to know if any are so close to Type 4 that winglet mods are putting them over the line?

If the winglets on the 737 were any larger it would be Class 4, since it measures in at 117' 5" with the winglets and 112' 7" without. The A32x baseline wingspan is about 112' as well. I would guess that the sharklets have been sized so as not to put them into Class 4.
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enilria
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RE: Class 3 Aircraft And Class 4 Aircraft

Tue Jan 12, 2010 5:03 pm



Quoting BMI727 (Reply 3):
If the winglets on the 737 were any larger it would be Class 4, since it measures in at 117' 5" with the winglets and 112' 7" without. The A32x baseline wingspan is about 112' as well. I would guess that the sharklets have been sized so as not to put them into Class 4.

I assume the fuel savings grows with the length? Any truth to that? Over time with high fuel there might be more pressure to extend them. Just wondering the impact it will have on gates at tight airports like LGA/DCA.
 
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RE: Class 3 Aircraft And Class 4 Aircraft

Tue Jan 12, 2010 5:07 pm



Quoting Enilria (Reply 4):
I assume the fuel savings grows with the length? Any truth to that?

Essentially, adding winglets (or raked wingtips) is in many ways like increasing the span.

Quoting Enilria (Reply 4):
Over time with high fuel there might be more pressure to extend them.

I'm sure that Tdscanuck can give a better answer than I, but my guess would be that there is a point of diminishing returns on the size of winglets. But the potential gains from bigger winglets may be cancelled out by the need for bigger gates.
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enilria
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RE: Class 3 Aircraft And Class 4 Aircraft

Tue Jan 12, 2010 5:16 pm



Quoting BMI727 (Reply 5):
I'm sure that Tdscanuck can give a better answer than I, but my guess would be that there is a point of diminishing returns on the size of winglets. But the potential gains from bigger winglets may be cancelled out by the need for bigger gates.

I found a document from Boeing:
http://www.boeing.com/commercial/airports/faqs/wingletspans.pdf

They show the 757 got a much larger winglet (8% wingspan increase instead of 4% increase). The Group 4 wingspan limits are wide enough to handle that. That makes me think there is additional savings from a bigger winglet.
 
arffdude
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RE: Class 3 Aircraft And Class 4 Aircraft

Tue Jan 12, 2010 6:11 pm



Quoting Enilria (Reply 2):
Happen to know if any are so close to Type 4 that winglet mods are putting them over the line?

I'm not aware of any off the top of my head, but along the same lines, the 737-800 is an ARFF index C airplane, whereas the previous 737 versions have fallen under ARFF index B. Index B covers aircraft up to 126', and then index C picks up from 126' - 159'. The 737-800 is 129' 6", so airports that previously only served smaller 737s had to step up their firefighting capabilities.
 
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enilria
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RE: Class 3 Aircraft And Class 4 Aircraft

Tue Jan 12, 2010 6:29 pm



Quoting ARFFdude (Reply 7):
The 737-800 is 129' 6",

The linked document shows the 737-800 is 117'5" with winglets. Any idea why the difference?
 
bassbonebobo
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RE: Class 3 Aircraft And Class 4 Aircraft

Tue Jan 12, 2010 8:48 pm



Quoting Enilria (Reply 8):

Quoting ARFFdude (Reply 7):
The 737-800 is 129' 6",

The linked document shows the 737-800 is 117'5" with winglets. Any idea why the difference?

The B738 is 129' 6" long. Aircraft length is used to determine the minimum emergency handling (firefighting, etc.) capabilities of an airport. The B731 through B73G all fall into Index B (90'-126') while the B738 and B739 fall into Index C (126'-159').
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packcheer
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RE: Class 3 Aircraft And Class 4 Aircraft

Tue Jan 12, 2010 11:55 pm

Some of you all seem to have a great deal of knowledge so question this..

Do the 757 and 767 (and their variants) fall into the same catagories for airports?

I ask because with a similar type rating, how easy is it for an airline to switch up from a 757 to a 767 at a whim if they need it? Going down in size surely isn't a problem (if a gate/firefigting equip can handle a 767 I'm sure it could handle a 757)
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vikkyvik
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RE: Class 3 Aircraft And Class 4 Aircraft

Wed Jan 13, 2010 12:04 am



Quoting Enilria (Reply 4):
I assume the fuel savings grows with the length? Any truth to that? Over time with high fuel there might be more pressure to extend them. Just wondering the impact it will have on gates at tight airports like LGA/DCA.

There will be a point at which longer winglets will start increasing fuel burn. At some point, the added structure (weight) to support the extra-long winglet will outweigh (no pun intended) the reduced drag.

It's similar to wing design, where you're considering wingflex, wingspan, sweep, etc. You want to arrive at the design that will end up costing you and your customers the least in the long run.

Quoting Enilria (Reply 6):
They show the 757 got a much larger winglet (8% wingspan increase instead of 4% increase). The Group 4 wingspan limits are wide enough to handle that. That makes me think there is additional savings from a bigger winglet.

At least for 737NGs, there is an additional consideration - the maximum wingspan accomodated at gates. Many gate spacings are sized to a 117.5 foot wingspan max. If you increase your wingspan beyond that, then you've suddenly made your 737 unable to fit at a hell of a lot of gates.
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arffdude
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RE: Class 3 Aircraft And Class 4 Aircraft

Wed Jan 13, 2010 2:37 pm



Quoting Packcheer (Reply 10):
Do the 757 and 767 (and their variants) fall into the same catagories for airports?

I ask because with a similar type rating, how easy is it for an airline to switch up from a 757 to a 767 at a whim if they need it? Going down in size surely isn't a problem (if a gate/firefigting equip can handle a 767 I'm sure it could handle a 757)

I just checked on Boeing website and apparently the 767 is 201' 4" in length, which just barely puts it into an ARFF Index E. Index E is the most demanding index and covers aircraft greater than 200' in length.

The important thing to remember though is that the regulation states that an airport's ARFF Index is determined by the longest air carrier which it is scheduled to receive five times a day or more. This means that an airline could swap a 757 for a 767 from time to time for whatever reason, but if they want to permanently upgrade the route to a 767, the airport must upgrade its ARFF facilities.
 
vikkyvik
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RE: Class 3 Aircraft And Class 4 Aircraft

Wed Jan 13, 2010 6:30 pm



Quoting ARFFdude (Reply 12):
I just checked on Boeing website and apparently the 767 is 201' 4" in length, which just barely puts it into an ARFF Index E. Index E is the most demanding index and covers aircraft greater than 200' in length.

The 767-400 is just over 200 feet. The -300 is around 180 feet, and the 200 is around 160.

The -400 also has a greater wingspan, with the addition of raked wingtips which the -300 and -200 do not have.
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HAWK21M
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RE: Class 3 Aircraft And Class 4 Aircraft

Thu Jan 14, 2010 2:28 am



Quoting Packcheer (Reply 10):

Out here AOCC prior to allotting the gates ensures the very aspect of Gate clearences depending on the Type Aircraft scheduled.
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