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A380 - Any Wash Separation Problems In Reality?  
User currently offlineArt From United Kingdom, joined Feb 2005, 3398 posts, RR: 1
Posted (7 years 1 week 1 day 5 hours ago) and read 9293 times:

Now that the A380 is actually taking off and landing at airports every day, are there any reports regarding the anticipated wash problems?

68 replies: All unread, showing first 25:
 
User currently onlineStitch From United States of America, joined Jul 2005, 31383 posts, RR: 85
Reply 1, posted (7 years 1 week 1 day 5 hours ago) and read 9296 times:
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I don't recall anything untoward being reported. I believe she still operates under "special" considerations with slightly larger separations, but as more of them enter service and airports become more familiar with them, hopefully those considerations will be removed (and I hope the same for the 747-8).

User currently offlineIkramerica From United States of America, joined May 2005, 21580 posts, RR: 59
Reply 2, posted (7 years 1 week 1 day 5 hours ago) and read 9268 times:



Quoting Stitch (Reply 1):
I believe she still operates under "special" considerations with slightly larger separations, but as more of them enter service and airports become more familiar with them, hopefully those considerations will be removed (and I hope the same for the 747-8).

That's what I expect. I know some people got all defensive about it, but frankly, for safety reasons, there's nothing wrong with doing it this way. There won't be a critical mass of A380s until 2009 at the earliest. The only airline it might impact at all would be SQ at that time, and if SQ wants to ignore the spacing, they can get the Singapore government to do so.



Of all the things to worry about... the Wookie has no pants.
User currently offlineCubsrule From United States of America, joined May 2004, 23295 posts, RR: 20
Reply 3, posted (7 years 1 week 1 day 3 hours ago) and read 9045 times:



Quoting Ikramerica (Reply 2):
The only airline it might impact at all would be SQ at that time, and if SQ wants to ignore the spacing, they can get the Singapore government to do so.

Also, it's not like either SYD or SIN is so horribly congested that a little extra spacing makes a big difference. When there are all kinds of 380s at LHR (and 380s comprise a larger portion of SQ's fleet), that will obviously change.



I can't decide whether I miss the tulip or the bowling shoe more
User currently offlineFuturecaptain From , joined Dec 1969, posts, RR:
Reply 4, posted (7 years 1 week 1 day 3 hours ago) and read 9001 times:



Quoting Art (Thread starter):
are there any reports regarding the anticipated wash problems?

Well, those second level windows are hard to wash as is the huge tail area. Of course, AF won't care about wash problems.  Smile

Now, the wake on the other hand...


User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3592 posts, RR: 66
Reply 5, posted (7 years 1 week 1 day ago) and read 8756 times:



Quoting Stitch (Reply 1):
I believe she still operates under "special" considerations with slightly larger separations, but as more of them enter service and airports become more familiar with them, hopefully those considerations will be removed (and I hope the same for the 747-8).

Wake separation requirements are a function of the physical characteristics of the airplane in question. No amount of operational familiarity will serve to reduce separation standards.

Until Airbus can provide data taken under controlled flight test conditions to the regulatory authorities (EASA, FAA and Eurocontrol) that shows the A380 wake is no greater than the 742/3/4, the current additional 1 nm separation between the A380 and other types in trail will remain in place. So far, Airbus has been unable to provide such a data set although they have done a substantial amount of additional testing.



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineIkramerica From United States of America, joined May 2005, 21580 posts, RR: 59
Reply 6, posted (7 years 1 week 1 day ago) and read 8710 times:



Quoting OldAeroGuy (Reply 5):
Wake separation requirements are a function of the physical characteristics of the airplane in question. No amount of operational familiarity will serve to reduce separation standards.

Standards are always adjusted (up and down) in all fields based on in practical experience. Initial testing can only tell you so much, and regulations based on initial tests should always be conservative to prevent disaster. Regulations can be relaxed over time.



Of all the things to worry about... the Wookie has no pants.
User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3592 posts, RR: 66
Reply 7, posted (7 years 1 week 1 day ago) and read 8653 times:



Quoting Ikramerica (Reply 6):
Standards are always adjusted (up and down) in all fields based on in practical experience. Initial testing can only tell you so much, and regulations based on initial tests should always be conservative to prevent disaster.

Not always true. Second segment climb requirements have not changed since the initial issue of FAR Part 25 nor have structural load factor requirements.

This is one of those areas where catastrophic results cannot be tolerated. It's not in the same category as relaxed structural inspections due to no observed damage during the original inspection interval.

What would be the basis for a change in separation requirements? If no incidents/accidents occur with the current separation standards, do you propose a continual reduction is separation until an incident/accident does occur?



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineThreepoint From Canada, joined Oct 2005, 2185 posts, RR: 9
Reply 8, posted (7 years 1 week 1 day ago) and read 8627 times:



Quoting Ikramerica (Reply 6):
Regulations can be relaxed over time.

Could you please share with me an example of where an aviation safety regulation has been 'relaxed over time', particularly after such a limited amount of in-service experience for the airplane type in question? I find it odd that some have claimed Airbus has devoted substantial flight testing with the hope of reducing separation-in-trail distances (which would of course be to their benefit) but yet your last post states that 'initial testing can only tell you so much". I wonder, which is it?

Until it is proven that the risks associated with following an A380 are no greater than those of a 747, you can expect the standards will remain as they are today.



The nice thing about a mistake is the pleasure it gives others.
User currently offlineZeke From Hong Kong, joined Dec 2006, 9229 posts, RR: 76
Reply 9, posted (7 years 1 week 23 hours ago) and read 8567 times:



Quoting Art (Thread starter):
Now that the A380 is actually taking off and landing at airports every day, are there any reports regarding the anticipated wash problems?

In Toulouse they have been operating the A380 in the circuit with many different aircraft types, large and small, and for the most part been treating it just like any other big jet with no reported problems.

Quoting OldAeroGuy (Reply 5):
Wake separation requirements are a function of the physical characteristics of the airplane in question. No amount of operational familiarity will serve to reduce separation standards.

It was "operational familiarity" not "physical characteristics" that lead to the FAA reducing the wake separation distances in the past.

At the moment many from the US are trying to rewrite history and put glass ceilings on what is and is not allowed for certification of new types, we saw many unnecessary impediments put in the place of the A380, and with the 787 and 748 we see many things being swept under the carpet.

Quoting OldAeroGuy (Reply 5):
Until Airbus can provide data taken under controlled flight test conditions to the regulatory authorities (EASA, FAA and Eurocontrol) that shows the A380 wake is no greater than the 742/3/4, the current additional 1 nm separation between the A380 and other types in trail will remain in place. So far, Airbus has been unable to provide such a data set although they have done a substantial amount of additional testing.

Airbus has sent, or is about to send another lot of data off.

Airbus does not need to show "A380 wake is no greater than the 742/3/4", that is a false statement. The wake an aircraft generates is somewhat irrelevant, it is how that wake effects following aircraft that is relevant.

It is somewhat false to think that ONLY "physical characteristics" determine the wake of an aircraft, it is physics of the aircraft passing through the fluid, not the "physical characteristics". Through smart design of the airframe they can change the outcome. We see that all the time with aircraft design, the simplest example is the vortex generator seen on many engine nacelles.

They were expecting standard heavy separation as a result of the latest set of tests, everything so far as been interim recommendations only.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineWingedMigrator From United States of America, joined Oct 2005, 2259 posts, RR: 56
Reply 10, posted (7 years 1 week 23 hours ago) and read 8544 times:



Quoting OldAeroGuy (Reply 5):
Wake separation requirements are a function of the physical characteristics of the airplane in question.

You are making the incorrect assumption that the standards are rigorously based on physics.

Quoting OldAeroGuy (Reply 5):
No amount of operational familiarity will serve to reduce separation standards.

The temporary standards for the A380 have already been relaxed at least once:

http://www.icao.int/icao/en/ro/apac/2007/FIT_SEA5/ip05.pdf

Paragraph 3 of this ICAO document states:

Quote:
It is anticipated that the group will undertake additional studies with a view to further refinement of this guidance on the basis of operational experience

(emphasis added). Since these additional studies have yet to be completed, to my knowledge, it is possible that further relaxation will be made in the A380 wake separation standards.


User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3592 posts, RR: 66
Reply 11, posted (7 years 1 week 23 hours ago) and read 8512 times:

Quoting Zeke (Reply 9):
It is somewhat false to think that ONLY "physical characteristics" determine the wake of an aircraft, it is physics of the aircraft passing through the fluid, not the "physical characteristics". Through smart design of the airframe they can change the outcome. We see that all the time with aircraft design, the simplest example is the vortex generator seen on many engine nacelles.

Pardon me, but aren't the physical characteristics of the airplane what determines the physics of the wake? Geometry of the airframe is certainly a physical characteristic as is airplane weight. Besides airplane weight and geometry, what other unique airplane characteristics determines the physics of the wake?

Quoting Zeke (Reply 9):
It was "operational familiarity" not "physical characteristics" that lead to the FAA reducing the wake separation distances in the past.

No, 747 testing outside of actual operations played a major part in the current separation standards. The physical characteristics either stayed the same or increased in the case of weight. Can you provide a reference where operational experience reduced separation distances for airplanes in trail to the 747?

Quoting Zeke (Reply 9):
Airbus has sent, or is about to send another lot of data off.

And the results of these data will be of great interest. However, they still are not the result of operational experience.

[Edited 2007-12-11 16:05:23]


Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineMir From United States of America, joined Jan 2004, 21852 posts, RR: 55
Reply 12, posted (7 years 1 week 23 hours ago) and read 8481 times:



Quoting Threepoint (Reply 8):
Could you please share with me an example of where an aviation safety regulation has been 'relaxed over time',

ETOPS. Started out as 120 minutes, then 138 got added on, then 180, then 207, and now we're looking at 330. Back when it first came out, if you had told people that an airplane could reliably fly 207 on one engine, they would have thought you were crazy. But it's been proven that it can be done, have the standards have gotten less restrictive with regard to what twins can do.

If the 380 proves that it can match the wake turbulence characteristics of a 747, then the separation can go down to the normal heavy separation.

-Mir



7 billion, one nation, imagination...it's a beautiful day
User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3592 posts, RR: 66
Reply 13, posted (7 years 1 week 22 hours ago) and read 8413 times:



Quoting Mir (Reply 12):
Quoting Threepoint (Reply 8):
Could you please share with me an example of where an aviation safety regulation has been 'relaxed over time',

ETOPS. Started out as 120 minutes, then 138 got added on, then 180, then 207, and now we're looking at 330.

Yes, the ETOPS diversion times have changed, but not because of a relaxation of standards. Increased diversion time is granted only through improvements to engine reliability and airplane system capability.

Engine reliability for 180 min ETOPS must be better than the standard required for 120 min ETOPS. Likewise, having cargo fire protection of 120 min won't allow you to fly 180 min.

Quoting WingedMigrator (Reply 10):
Quoting OldAeroGuy (Reply 5):
Wake separation requirements are a function of the physical characteristics of the airplane in question.

You are making the incorrect assumption that the standards are rigorously based on physics.

No, I'm not assuming there is a rigorous application. However, the difference in separation between a 747 in trail to a 747 and a 737 in trail to a 747 is based on the physical characteristics of both airplane.

Quoting WingedMigrator (Reply 10):
Quoting OldAeroGuy (Reply 5):
No amount of operational familiarity will serve to reduce separation standards.

The temporary standards for the A380 have already been relaxed at least once:

http://www.icao.int/icao/en/ro/apac/...5.pdf

Yes, but as your reference states, this change was based on the data from the flight test program, not operational experience. See page 2 paragraph 2 of the document (part of the cover letter).

Quoting WingedMigrator (Reply 10):
Paragraph 3 of this ICAO document states:

Quote:
It is anticipated that the group will undertake additional studies with a view to further refinement of this guidance on the basis of operational experience

(emphasis added). Since these additional studies have yet to be completed, to my knowledge, it is possible that further relaxation will be made in the A380 wake separation standards.

It will be interesting to see if there is a concrete proposal for actual inservice operational studies or if this refers to the data Zeke quotes.

Quoting Zeke (Reply 9):
Airbus has sent, or is about to send another lot of data off. ..................

They were expecting standard heavy separation as a result of the latest set of tests, everything so far as been interim recommendations only.

Again, these are not inservice operational data, but a new set of Airbus flight test data.



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineTheSonntag From Germany, joined Jun 2005, 3760 posts, RR: 29
Reply 14, posted (7 years 1 week 22 hours ago) and read 8373 times:



Quoting OldAeroGuy (Reply 13):
Engine reliability for 180 min ETOPS must be better than the standard required for 120 min ETOPS. Likewise, having cargo fire protection of 120 min won't allow you to fly 180 min.

Yes, but the fact that Etops 180 exists is a revolution itself. No doubt that there must be special provisions in place, but with 1960s technology, nobody would have thought about Etops 180 at all, that was unthinkable at that time.


User currently offlineThreepoint From Canada, joined Oct 2005, 2185 posts, RR: 9
Reply 15, posted (7 years 1 week 22 hours ago) and read 8347 times:



Quoting Mir (Reply 12):
ETOPS. Started out as 120 minutes, then 138 got added on, then 180, then 207, and now we're looking at 330.

I would argue that the standards haven't relaxed at all, they are progressively newer standards based upon new requirements. There are successive hurdles an aircraft must surpass in order to be permitted to fly further distances (as measured by time) from suitable aerodromes. Your logic would indicate that an aircraft originally certified for ETOPS 120 means it can now fly ETOPS 207 without further modification.



The nice thing about a mistake is the pleasure it gives others.
User currently offlineMir From United States of America, joined Jan 2004, 21852 posts, RR: 55
Reply 16, posted (7 years 1 week 22 hours ago) and read 8316 times:



Quoting Threepoint (Reply 15):
I would argue that the standards haven't relaxed at all, they are progressively newer standards based upon new requirements.

The standards used to be "no twin engine airplanes beyond 60 minutes of a suitable airport". Those standards then got relaxed, with certain provisions. Then they got more relaxed, with more provisions.

If Airbus can demonstrate that a 380's wake is no different from that of a 747, then the separation will go down. Call it new standards based on demonstrated capabilities if you like, call it a relaxation of standards if you like, but it comes to the same thing.

-Mir



7 billion, one nation, imagination...it's a beautiful day
User currently offlineZeke From Hong Kong, joined Dec 2006, 9229 posts, RR: 76
Reply 17, posted (7 years 1 week 21 hours ago) and read 8294 times:



Quoting OldAeroGuy (Reply 11):
Pardon me, but aren't the physical characteristics of the airplane what determines the physics of the wake? Geometry of the airframe is certainly a physical characteristic as is airplane weight.

Nope, it is how the lift is generated.

The simplest example of how you are incorrect is by comparing a 744 landing at the same mass at flap 20 and landing at full flap, they generate different wake turbulence signatures despite having the same physical characteristics. The high lift devices play a major role in the generation of the wake turbulence.

Quoting OldAeroGuy (Reply 11):
Besides airplane weight and geometry, what other unique airplane characteristics determines the physics of the wake?

Even Boeing have acknowledged that the A380 has a better wing than even the 748i.

Airbus put a lot of work into the wing design, it has unique leading edge devices, and almost full span high lift devices, a large wing fence, high bypass engines, and a modern airfoil section, all of which influence the high lift characteristics of the aircraft, and subsequently the wake generation.

Quoting OldAeroGuy (Reply 11):
Can you provide a reference where operational experience reduced separation distances for airplanes in trail to the 747?

Good presentation on the development of the current standards http://wwwe.onecert.fr/projets/WakeN...retigny-november/James_Hallock.pdf

I dont think you are aware of a number of the steps given your posts.

Quoting OldAeroGuy (Reply 11):
And the results of these data will be of great interest. However, they still are not the result of operational experience.

Any data that is produced from flight testing is "operational" experience, you have made the leap to assume it only means commercial activities.

Quoting OldAeroGuy (Reply 13):
Yes, but as your reference states, this change was based on the data from the flight test program, not operational experience. See page 2 paragraph 2 of the document (part of the cover letter).

Where does it say COMMERCIAL operational experience ?

Quoting Threepoint (Reply 8):
Could you please share with me an example of where an aviation safety regulation has been 'relaxed over time', particularly after such a limited amount of in-service experience for the airplane type in question? I

Wake turbulence standards have changed over time, even the 747 when introduced had about a 10 nm separation standard. Also have a look at http://wwwe.onecert.fr/projets/WakeN...retigny-november/James_Hallock.pdf

Other aspects in aviation where you have seen similar changes would be RVSM (imperial and now metric), RNP, MNP, which like the changes in wake separation standards are designed to get more aircraft in a given volume of airspace.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3592 posts, RR: 66
Reply 18, posted (7 years 1 week 21 hours ago) and read 8278 times:



Quoting Mir (Reply 16):
The standards used to be "no twin engine airplanes beyond 60 minutes of a suitable airport". Those standards then got relaxed, with certain provisions. Then they got more relaxed, with more provisions.

If Airbus can demonstrate that a 380's wake is no different from that of a 747, then the separation will go down. Call it new standards based on demonstrated capabilities if you like, call it a relaxation of standards if you like, but it comes to the same thing.

Hardly. At 60 min ETOPS, there was no standard for engine reliability. Fro 120 min ETOPS, a new tougher safety standard for engine reliability was established, improving safety for both 60 and 120 min ETOPS.

And rather than saying that if the A380 wake is no more adverse, then the standard can be relaxed (ie less safe), the better way to thing about it is that equivalent safety can be maintained by reducing the separation distance.

Of course, the trick is to show that the A380 wake and the 747 wake represent an equivalent hazard so an equivalent separation is appropriate.



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineThreepoint From Canada, joined Oct 2005, 2185 posts, RR: 9
Reply 19, posted (7 years 1 week 21 hours ago) and read 8247 times:



Quoting Zeke (Reply 17):
Other aspects in aviation where you have seen similar changes would be RVSM

Yup. As soon as I had my debate with Mir, I remembered RVSM. It is, in hindsight, a fairly recent and obvious example.
Now, after some dinner, it seems I have a pdf file to read.



The nice thing about a mistake is the pleasure it gives others.
User currently offlineWingedMigrator From United States of America, joined Oct 2005, 2259 posts, RR: 56
Reply 20, posted (7 years 1 week 18 hours ago) and read 8135 times:



Quoting Zeke (Reply 17):
The high lift devices play a major role in the generation of the wake turbulence.

 checkmark 

To first order, the high lift devices determine the speed at which the airplane may fly. Regardless of speed, the airplane must impart a constant rate of downward momentum to the air in order to stay aloft. This constant rate of downward momentum is reacted as lift. The slower the airplane flies, the stronger the wake, since the downward momentum is imparted to a smaller path length of air per unit time.

As you point out, the design details of the high lift devices have a strong influence on how quickly the turbulence decays.

Quoting OldAeroGuy (Reply 5):
No amount of operational familiarity will serve to reduce separation standards.

I'm glad you've come around from this viewpoint.  Wink


User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3592 posts, RR: 66
Reply 21, posted (7 years 1 week 17 hours ago) and read 8053 times:

Quoting Zeke (Reply 17):
The simplest example of how you are incorrect is by comparing a 744 landing at the same mass at flap 20 and landing at full flap, they generate different wake turbulence signatures despite having the same physical characteristics.

What are you talking about? Flaps 20 and Flaps 30 (full landing flap) have different physical characteristics. These consist of different flap angles on the fore, main and aft flaps as well as different amounts of Fowler motion. Since the physical characteristics of the flaps change when going from Flaps 20 to Flaps 30, it is no surprise that the wake characteristics are different between these two flap positions.

In addition, landing at Flaps 20 will require a higher landing speed than Flaps 30. The speed change alone will also impact wake characteristics.

Quoting Zeke (Reply 17):
Airbus put a lot of work into the wing design, it has unique leading edge devices, and almost full span high lift devices, a large wing fence, high bypass engines, and a modern airfoil section, all of which influence the high lift characteristics of the aircraft, and subsequently the wake generation.

Aren't these all geometric changes and therefore changes in the airplane physical characteristics, as I stated? Unfortunately, Airbus has not been able to show that these physical characteristics have been able to overcome the primary physical characteristics the A380 impacting wake characteristics (Weight, Span and Approach Speed) to produce wake vortex characteristics that will allow the same separation distance for airplanes in trail as for the 747.

Quoting Zeke (Reply 17):
Quoting OldAeroGuy (Reply 11):
Can you provide a reference where operational experience reduced separation distances for airplanes in trail to the 747?

Good presentation on the development of the current standards http://wwwe.onecert.fr/projets/WakeN...retigny-november/James_Hallock.pdf

I dont think you are aware of a number of the steps given your posts.

Please read my post again and your own reference. I'm very aware of the history of wake separation standards.

Page 3 of your reference shows that the initial separation for the 747 was 10 nm. Page 4 of the reference says that this distance was then reduced to 4 nm for Large airplanes and 5 nm for Small airplanes in trail of Heavies. Note that Page 4 also says that this change was made as the result of flight test data, not operational data. This is what I pointed out previously.

Quoting OldAeroGuy (Reply 11):
No, 747 testing outside of actual operations played a major part in the current separation standards.

The remainder of the reference describes the use of operational data to increase separation distances for other airplanes in trail to Heavies. There is no instance for an airplane in a lower category having its trail distance to a Heavy being reduced. I see no contradiction to my original statement in this reference.

Quoting OldAeroGuy (Reply 11):
Can you provide a reference where operational experience reduced separation distances for airplanes in trail to the 747?



Quoting Zeke (Reply 17):
Any data that is produced from flight testing is "operational" experience, you have made the leap to assume it only means commercial activities.



Quoting Zeke (Reply 17):
Where does it say COMMERCIAL operational experience ?

Commercial operation does seem to be the thrust of this thread. If an A380 is undelivered and does not have an individual airworthiness certificate, then any flight it performs is a flight test.

Quoting Zeke (Reply 17):
Other aspects in aviation where you have seen similar changes would be RVSM (imperial and now metric), RNP, MNP, which like the changes in wake separation standards are designed to get more aircraft in a given volume of airspace.

None of these changes were made solely on the basis of operational data. Physical changes were made to the airplanes to enable the improved operation. Before operational use of these updates were permitted, operational data were collected to ensure that the planned improvements were verified in commercial operation. For example, RVSM was verifed by overflying ground height measuring radar and compared with transponder encoded altitudes. Only when airplanes were shown to have altitude deviations within an acceptable error band was RVSM put into effect.

I'm curious how Airbus will construct a similar operational verification of A380 wake vortex characteristics to allow a reduction in separation distances without endangering trail aircraft. Will Airbus install LIDAR systems at various airports and compare the wake vortex characteristics of 747's and A380's? To make sense of the data, the 747 operators will need to provide operational data for the 747's in the samples. It will be interesting to see if the 747 operators are cooperative.

[Edited 2007-12-11 21:41:19]


Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3592 posts, RR: 66
Reply 22, posted (7 years 1 week 17 hours ago) and read 8046 times:



Quoting WingedMigrator (Reply 20):
Quoting OldAeroGuy (Reply 5):
No amount of operational familiarity will serve to reduce separation standards.


I'm glad you've come around from this viewpoint.

Huh? My position is still unchanged.



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
User currently offlineFlighty From United States of America, joined Apr 2007, 8759 posts, RR: 3
Reply 23, posted (7 years 1 week 17 hours ago) and read 7991 times:

1nm ain't much. Heard anecdotal reports that it's a 5 minute gap, or so. At 200 knots, that's easily 15nm.

Quoting OldAeroGuy (Reply 21):
It will be interesting to see if the 747 operators are cooperative.

I know one 744 operator that would cooperate. Singapore.


User currently offlineZeke From Hong Kong, joined Dec 2006, 9229 posts, RR: 76
Reply 24, posted (7 years 1 week 16 hours ago) and read 7944 times:



Quoting OldAeroGuy (Reply 21):

What are you talking about? Flaps 20 and Flaps 30 (full landing flap) have different physical characteristics.

It seems very clear to myself and others you were trying to push the argument an aircraft with the physical characteristics of mass x and wingspan y will produce a wake of z. You agree with me that two 747-400s that have the SAME physical characteristics and mass can have different wake characteristics just by varying the flap setting used for landing.

Even if you were to scale up the 744 wing and mass by 10%, does not mean you will get 10% more wake.

It is NOT the the physical characteristics of the 744 which generates the wake, it is the physics that produce the lift, and as with anything to do with aircraft design, the number of possible combinations are endless.

It is the improved understanding of the physics which lead to the better wing design on the A380 over the 744, just like better understanding of the physics of engines has seen the improvement of the GEnx over the CF6.

It is the better understanding of the physics that allows the A380 to takeoff and land in distances less than that of a 744, it is the same improved knowledge of the physics which improved the wake generation.

Quoting OldAeroGuy (Reply 21):
Airbus has not been able to show that these physical characteristics have been able to overcome the primary physical characteristics the A380 impacting wake characteristics (Weight, Span and Approach Speed) to produce wake vortex characteristics that will allow the same separation distance for airplanes in trail as for the 747.

With respect, it is obvious to me you have no idea of what Airbus has been able to show.

Airbus does not need to show "same separation distance for airplanes in trail as for the 747", as the 747 is not the upper or lower end of the heavy category. Aviation does not revolve about Boeing, nor do important safety issues like this.

Quoting OldAeroGuy (Reply 21):
There is no instance for an airplane in a lower category having its trail distance to a Heavy being reduced. I see no contradiction to my original statement in this reference.

All of your posts seems like a contradiction, seems like you are back peddling.

Boeing has been adding higher mass, new engine, different wings to the 747 over the years without any testing, all of a sudden when a competitor enters the market segment the competitor has to do a heap of testing and validation work because of what in my view is a campaign launched by Boeing marketing to the industry under the guise of a "safety" problem.

If Boeing were serious about this issue, instead of paying lip service to it they would schedule a scientific analysis of the 787 and 748 wake characteristics during the flight test program.

Quoting OldAeroGuy (Reply 21):
I'm curious how Airbus will construct a similar operational verification of A380 wake vortex characteristics to allow a reduction in separation distances without endangering trail aircraft. Will Airbus install LIDAR systems at various airports and compare the wake vortex characteristics of 747's and A380's?

I have pointed on a number of these wake threads, LADIR has been installed at a number of "normal" airports already, both in Europe and in the US, and research is under the way to have active wake separation based upon reading the real time wake hazard.

Airbus also installed LADIR at controlled airports for scientific testing under EASA/JAA supervision, as well as airborne LADIR measurements for in trail measurements.

Airbus has done the research, and now have the scientific knowledge to be the world leaders in this area.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
25 OldAeroGuy : As it now stands, they have not been able to convince the EASA/JAA, Eurocontrol and the FAA that the A380 does not require additional separation. If
26 Cubsrule : This is hardly bias toward Boeing as you asserted above, though. Derivative aircraft are subject to less rigorous scrutiny than new types. That's tru
27 Zeke : Seems you are the one who does not know what they are talking about. ICAO is not a regulatory body, this has not been driven by EASA or the FAA, the
28 Cubsrule : Right. Boeing thinks it does not need to do it because it didn't do it for the 742, 742SUD, 743, or 744...
29 Zeke : Boeing has NEVER done it or ANY aircraft. It does not know what it talking about.
30 Cubsrule : I'm not (necessarily) arguing with either of those assertions. However, it's important to note that everyone is playing by the same rules.
31 OldAeroGuy : Seems that you have another comprehension problem. I described the EASA/JAA, Eurocontrol and the FAA as regulatory bodies, not ICAO. I eagerly await
32 Zeke : The rules don't exist, they is why Boeing is trying to put a glass ceiling on the heavy category at 1 million pounds, so they dont need to test the 7
33 Cubsrule : I hadn't heard that... do you happen to have a source handy?
34 CHRISBA777ER : As a derivative of the 747, will the 748 have to undergo the same testing as the A380 has?
35 Post contains links Zeke : No problem with comprehension at all. The Airbus wake vortex group reported to ICAO, which is not a regulatory body. It could have had members from t
36 Cubsrule : I'm not sure what, if anything, that proves. You can hardly compare 1960s technology to current technology, and obviously, we have far more experienc
37 Post contains images Zeke : I agree totally, and it why Airbus is using science to show the A380 poses no more danger than other large aircraft to trailing aircraft. What the sc
38 Moo : Then why do grandfathering rights stand?
39 Cubsrule : That's a darn good question. In the U.S. at least, very little grandfathering actually appears in Part 25 (our certification regulations for transpor
40 Zeke : Interesting philosophical question that deserves its own thread. I think they were put in place for simple derivatives of a base certified airframe,
41 Cubsrule : Well said. The 737, 747, and CL-600 are probably the three best examples of inappropriate, but perfectly legal, grandfathering. Had Airbus built the
42 Tdscanuck : You can substantiate something by analysis or by test. If you have a giant pile of existing data and your change is incremental, analysis is almost a
43 Post contains links OldAeroGuy : Zeke, You have quite a style on this discussion board. First, you write something that is not factual. Then when I point out your error, you respond t
44 Aerokiwi : Such a strange thread. OldAeroGuy simply points out that issues such as aircraft separation and ETOPS are only ever changed/updated based on non-opera
45 Post contains images Baroque : Ditto Ak. I too regret the tone that developed as we were starting to find out some interesting material though the exchanges were still interesting.
46 Sllevin : I thought RVSM required equipment better than originally required? IOW, the standard changed because the underlying requirements changed. Steve
47 Post contains images Ikramerica : Thanks for setting the record straight. I get annoyed when people knowingly post false information on these forums, and it's helpful to have the fact
48 Post contains links Zeke : I agree that the A380 should have been tested, but we also had the C5, AN124, AN225 flying about for some time. Boeing know less about the 744 wake t
49 Dakota123 : Frankly I would be more inclined to trust results of NASA (for example) than a proponent such as Airbus (or Boeing, for that matter).
50 PolymerPlane : So why the hell is the first author of that report was a Boeing's engineer, paid by Boeing? And the title of the work is "Result of the Boeing Compan
51 Post contains links OldAeroGuy : Vortex strength and its decay characteristics are a function of: Airplane Weight Wing Span Operating Speed Wing/High Lift System Design Details 1) Wi
52 M27 : Be that true or not, you don't know that and neither does Airbus! I'm pretty sure you don't know what Airbus has done, little alone Boeing. Another s
53 Post contains links OldAeroGuy : Quoting Zeke (Reply 48): Quoting OldAeroGuy (Reply 43): Then when I point out your error, you respond that I'm being disingenuous and print another un
54 OldAeroGuy : PS to Zeke. Read the report you've referenced below. On the first page, near the bottom of the right column, you'll find this quote from Mr. Primeggia
55 Post contains images Zeke : Considering it was published by the FAA would indicate that it was part of the FAA program. We have many Boeing and Airbus employees on this site, th
56 Group51 : I agree. I propose that EASA funds a test programme to examine the wake performance of the A380 to ensure safe and efficient operation against the 74
57 Post contains images Baroque : Most things in physics come to me as a surprise, but not this particular one! However, while the wake might be defined as stronger in terms of moment
58 OldAeroGuy : But they do construct the the pressure bulkhead. And Boeing did do wake vortex testing on its own aircraft, something you said they never did. Boeing
59 Post contains links PolymerPlane : So what? I can split hair with you too. The A380 wake turbulence was not done by Airbus. It was done by the A380 steering group which includes repres
60 Post contains links JetMech : I think that wake strength has a stronger relationship to the coefficient of lift rather than the velocity of the air over the airfoil surface. Assum
61 Post contains links Zeke : Please see the Gnat chart on page 5 of the following document http://wwwe.onecert.fr/projets/WakeN...0group%20Update%20%5BGreene%5D.pdf Airbus did th
62 Tdscanuck : For a given weight aircraft, in general: -Increasing wingspan will decrease wake turbulence (wider vortex sheet) -Tips are aerodynamically the same a
63 Post contains images WingedMigrator : So new that the acronym is sometimes confused It is LIDAR (LIght Detection And Ranging)
64 Zeke : Correct, my typo.
65 Post contains links Glacote : Airbus is still carrying tests : http://www.ladepeche.fr/article/2007...-A-380-n-etait-qu-un-exercice.html Airbus purposedly injected lubricant into t
66 OldAeroGuy : Do you the mean ICAO interpretation of the data or the reality of the data?
67 Glacote : I am biased. I believe that the A388 wake is higher but only marginally so - and that the Icao has taken too conservative a view. This is based mainl
68 Post contains links OldAeroGuy : It depends on what you consider "marginal" to mean. Please see the equation at the top of page 3 of this link. http://gltrs.grc.nasa.gov/reports/20..
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