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Knold
12th Nov 2018, 07:26
Hi all,

Iíve been flying for close to 20 years now. The risks of wake turbulence has always been on my mind but more so over the last few years as I went from a medium jet to a light one.

After scouring the interwebs for numbers and information I canít really find any specifics. My main concern is with the A380 but obviously also other heavy aircraft.

As far as descend rates of a vortex, Iíve seen anything from 300-700 fpm.
There are statements that a vortex wonít descend more than 1000 feet in total.
That they donít last longer than 3 minutes. I feel this might not be conservative enough.

The questions I have are if anyone has any solid info on (relating to A380):

A. Lifespan of a vortex.
B. Max vertical movement.


Obviously things like atmospheric conditions and weight of the traffic will effect but assuming worst case is what Iím looking for here.

underfire
12th Nov 2018, 17:08
There are many, many factors. Atmospheric conditions being significant. Are you looking for details on final approach or enroute?

gearlever
12th Nov 2018, 17:54
German Challenger Totaled After A380 Wake Turbulence (http://aviationweek.com/ebace-2017/german-challenger-totaled-after-a380-wake-turbulence)

RVF750
12th Nov 2018, 18:00
All I know is that I stay well clear of the recent track of an A380. I just missed one a few months back and it caught the wingtip of our 737 and gave the whole plane a shake. Crossing 1000ft under him, we almost passed through his visible wake, but I turned to avoid and just caught it, maybe 10nm behind him...

Airmann
13th Nov 2018, 01:43
I fly a heavy but have still experienced nasty jolts passing through 380 wake.

To be safe I would be conscious of wake even up to 40 NM away. That would equate to around 5 minutes. Sure that's probably a bit too far to really effect you but I wouldn't play around. Inside of 20NM I would consider wake turbulence critical.

If you are visual with the aircrafts contrail then expect the wake to start with the contrail and then descend below it. So if the aircraft is we'll passed you don't worry about flying through it's contrail if it's near then don't

Yes it's totally dependent on atmospheric conditions but as a rule of thumb if passing behind, take the wake aircrafts distance away from you when you expect to cross it's wake trail and multiply by 50 to get a reference altitude then take a window of plus/minus 500 feet. I.e. if aircraft is 10NM then x 50 = 500ft. So take a window of 0-1000ft. At 20NM x 50 = 1000ft so window is 500-1500ft. If you're passing behind at these altitudes then take wake seriously. (Past 10NM I would even suggest adding plus 1000ft to the reference altitude)

It's not an exact science but I hope it keeps you safe.
​​​​​​

Knold
13th Nov 2018, 14:18
Thanks Airmann.

My thinking are along the same lines and I exercise extreme caution. 2000 below I still consider it a risk and up to 5 minutes after.

But this is mainly based on feelings and guesses rather than anything solid.

I really wished there was some study to say "a vortex can/cannot descend more than 2000 feet" or "The vortex of a A380 in cruise holds energy for up to 5 minutes".

I find it utterly bizarre that this is not part of a certification process for a new aircraft. It should be up to Airbus when designing the monstrosity to study how badly it will effect other traffic.

underfire
13th Nov 2018, 17:34
There was a wake encounter at DBX, A320 on final to 30L, hit a A380 wake from 30R at about 500 feet, rolled 40 degrees left, then 40 degrees right, ended up landing on 30R.

There are some studies now of the FDR data, using an equation equating to the sudden change in G force (how ever small). There are far more wake encounters that previously known. Also, most drivers dont take the time to report an encounter.
Using this data, there is are studies to determine acceptable levels of wake encounter.

It is not only the A380 to worry about. One of the deadliest ones I have measured was from a B787. The same high velocity, but a larger core, and long lasting. Many measurements of this ac in many conditions. Heaven help a 320/737 variant in trail to one of those.
Similar wings, although not as upswept, the A350, but only measured that ac once.

On the trail. The conditions that cause a trail do have significant effect on the wake. You will notice on many of the videos, the rollup does not occur very much below the ac, and does not appear to drop very much relative to the ac position. You can actually watch the wake slow to a stop not too far behind the ac.One has to believe that the conditions have to slow the wake down quite a bit.

A380 wake enroute

Knold
13th Nov 2018, 17:42
Thanks Underfire, nice post.

I always assumed that the A380 had extra nasty wake because the wings are too short and therefore giving a high wingload. I wouldnít have thought a 787 would give very bad ones though.

underfire
13th Nov 2018, 19:58
Knold,

The size of the vortex is directly related to wingspan. Terminal velocity, which is the highest velocity the air can achieve, is constant through all aircraft types. The size of this core is not. Looking at the A380 in the video, you get an idea of the size of the vortex on rollup, note that it is about exactly the length of the individual wing.
What you do see remaining is the high velocity core of the vortex.
Note that the wake core is not really descending in this video. (nor drifting sideways)

look at this beast of a wake...

787 wake

B2N2
13th Nov 2018, 20:30
Two questions:

1. What do you consider a light jet?
2. A380 is used for long range/ultra long range so what makes you think youíll be encountering it?

Knold
14th Nov 2018, 03:11
Two questions:

1. What do you consider a light jet?
2. A380 is used for long range/ultra long range so what makes you think youíll be encountering it?

1. In my case I fly a Challenger 604. I would consider any BizJet a light one.
2. What do you mean? Because they can fly for 15 hours they are somehow on different airways? I don't think, I know. I encounter well over 20 every time we go flying. Try flying from the ME up to Europe without using the A380 expressway through Iraq and Turkey. Go back to sleep buddy.

xanda_man
14th Nov 2018, 08:59
2. A380 is used for long range/ultra long range so what makes you think youíll be encountering it?
This is way off the mark and completely irrelevant, if it's in the air for 5 minutes there's always the possibility of encountering it :rolleyes:

Plus the A380 is used for short/medium-haul the world over. Didn't EK announce DXB-DOH @ 55 mins...... CZ use it on sub 4 hour sectors then there's Europe to the Middle East @ around 5 hours

Airmann
14th Nov 2018, 11:00
The corridors for flights out of the Gulf through Iraq/Iran to the North West basically consist of only around 2 or 3 airways. And are used by the airline with the largest number of 380s in the world.

For this reason pilots out of Gulf are now hyper consious of 380 wake. I have myself hit 380 wake twice in the last three years in a heavy. And it was the same as hitting the wake of a heavy in a medium Jet. We all know what happened to the German business jet that flew through the wake of a 380 over the Arabian Sea.

Unfortunately, or fortunately it was not until that event that the 380 wake problem became well known enough to wake up the authorities. However, the issue is still not officially dealt with. ATC need to be more aware when a 380 is around and be especially careful when a light or medium jet may be pottentially crossing it's path. That could mean a call to the pilots of the light jet of the precense of a 380 or to enforce stricter seperation minimum.

sierra_mike
14th Nov 2018, 11:34
That could mean a call to the pilots of the light jet of the precense of a 380

i hear that call quite frequently in europe. e.g. "you are crossing x miles behind an a380, can you accept that?"

underfire
14th Nov 2018, 15:38
and the 747 series doesnt make a wake...

B2N2
14th Nov 2018, 15:45
1. In my case I fly a Challenger 604. I would consider any BizJet a light one.
2. What do you mean? Because they can fly for 15 hours they are somehow on different airways? I don't think, I know. I encounter well over 20 every time we go flying. Try flying from the ME up to Europe without using the A380 expressway through Iraq and Turkey. Go back to sleep buddy.

Legitimate question ace.
I consider a Ďlightí jet like a CJ2 or Phenom.
If you fly exclusively domestic USA on demand charters you will not encounter a lot of A380ís

You could have put your area of operations in your original post. Would have helped.
How about paying attention any time you hear Ďsuperí on your frequency.

hans brinker
14th Nov 2018, 17:42
Legitimate question ace.
I consider a Ďlightí jet like a CJ2 or Phenom.
If you fly exclusively domestic USA on demand charters you will not encounter a lot of A380ís

You could have put your area of operations in your original post. Would have helped.
How about paying attention any time you hear Ďsuperí on your frequency.

Just the use of "ace" refutes the whole "legitimate".
Your "it must be in the USA if it is about flying" makes you the problem here, not the guy who asked the question. How about not assuming things you know nothing about...

Knold
14th Nov 2018, 17:57
Hey B2N2, I donít think you are contributing in any way here guy.

I fly worldwide, including domestic US. Of course there is less of a chance to run into a 380 there, but you still could. Even if I wasnít doing the majority of my flight between the ME and Europe, I donít see why a legitimate question about the under-researched science of wake turbulence isnít warranted. The fact that you think all flying is about the US is just weird.
If I have 1, 20 or 40 years under my belt shouldnít matter either.
Frankly your sarky comment about European training says a lot about you.

Finally, I do pay attention when I hear Super on the radio. Doesnít really mitigate the risk though does it? But how would you know since your area of operation is 380-free?

Yours sincerely Ace

Thanks for your input Airmann, Xanda, Hans Brinker

Airmann
14th Nov 2018, 21:03
i hear that call quite frequently in europe. e.g. "you are crossing x miles behind an a380, can you accept that?"

Ok never heard that.


But nevertheless shouldn't be left to the pilots should it? Good to ask, but like the original poster said, would be better if there was some concrete figures. They don't ask the pilot about seperation anywhere else, it is what it is and the ATC enforces it.

Airmann
14th Nov 2018, 21:13
If you fly exclusively domestic USA on demand charters you will not encounter a lot of A380ís


Exactly why ATC should be more careful. 380s aren't that common in most parts of the world, so when one does show up ATC should be there to protect the rest of the guys.

Anyone trying to gain more experience is great. Shame that most people only come on here to bitch and moan. PPrune is an amazing tool, to be able to ask people that have more knowledge than you is great, especially when certain information isn't available within your operation. I know that I'm a better pilot for it.

Private jet
14th Nov 2018, 22:33
What is it about Chally's and A380's? I'm another with such "experience", not extreme but very exceptional, 2k below, crossing about 12 behind ( so basically about a minute 30 secs) A Malay machine, not that that makes any difference. I've never heard of the "A380 warning" either & as the previous poster alludes to, either the seperation standard is good enough or it isn't. Too much "politics" from ATC now, but perhaps thats a new topic!

Mad (Flt) Scientist
15th Nov 2018, 04:48
I find it utterly bizarre that this is not part of a certification process for a new aircraft. It should be up to Airbus when designing the monstrosity to study how badly it will effect other traffic.

Ah, but airbus DID study this. I'm sure there must be info available on it publicly, it's quite an interesting piece of work. airbus link heer for starters ... (https://www.airbus.com/newsroom/press-releases/en/2006/09/airbus-a380-wake-vortex-study-completed.html)

Basically, when the 380 was first being brought into service, there were fears expressed that it might have an excessive wake, and various ideas were mooted in terms of an extra-special category for it, extra long separation criteria, etc. All things airbus wanted to avoid if they could justify that, based on actual data rather than a general "its a monster lets treat it like one" reaction.

So they set up a series of wake encounters using a single-aisle as the 'target', various different large aircraft (not just the 380, they wanted to see the behaviour in context) as the generators, plus some other research aircraft gathering data. What they found indicated that the 380 isn't a 'monster' and resulted in the separation criteria we have today. They also had some interesting findings on what the best (and worst) response was by a target finding itself being "waked".

Knold
15th Nov 2018, 08:21
Thanks Mad (flt) Scientist. Interesting stuff.

Gonzo
15th Nov 2018, 10:20
The scientific approach to determining wake strength used for the A380 has been applied across the spectrum, hence the RECAT-US and RECAT-EU schemes, and the forthcoming Static Pair Wise Separation.

I'd rather use a wake scheme based on science than the ICAO 'finger in the air' categories and separations that most of the world still use.

OldLurker
15th Nov 2018, 10:35
Just to be clear: is it being stated or claimed here – by those who are experienced in the game – that en route wake from a "super" A380 is worse, more to be avoided, than wake from a large "heavy" such as a 747-8 or a 787? The "beast of a wake" that underfire posted at #9 was from a 787.

Gonzo, can you briefly explain (for benefit of this small-aircraft pilot) about the forthcoming Static Pair Wise Separation?

misd-agin
15th Nov 2018, 16:40
German Challenger Totaled After A380 Wake Turbulence (http://aviationweek.com/ebace-2017/german-challenger-totaled-after-a380-wake-turbulence)

Review the FDR data. Itís in the web. Some, and perhaps a lot, of the damage came from poor recovery inputs by the pilot(s).

misd-agin
15th Nov 2018, 16:49
Approx 15-25 nm in trail is the risk area. Inside of 15 nm it would need to desecebd at 500 FPM to be 1000Ē lower. After 25 nm youíre outside of three minutes.

The wake isn't visible. Absent a significant wind shift contrails will give you a good indication of where the wake is.

Wake is a function of weight, wingspan, and AOA. All the larger twins have wingspans in the 210í (65 m) range. And it drops 1000í. Been there done that. Moderate turbulence in a 777 behind a 747-400 at cruise.

ManaAdaSystem
15th Nov 2018, 18:27
I have been warned about crossing behind and below the A380 a few times in European airspace.
I have been vectored in order to get further away from it, and I have been asked to climb 1000 ft to get above the wake. We were to heavy but the controller was happy to let us climb two hundred feet and then return to our cleared altitude after we passed the A380 track.
Not sure if the controllers have to do any active separation, but I don’t mind if they do. I fly 737.

underfire
16th Nov 2018, 01:48
The scientific approach to determining wake strength used for the A380 has been applied across the spectrum, hence the RECAT-US and RECAT-EU schemes, and the forthcoming Static Pair Wise Separation.

I'd rather use a wake scheme based on science than the ICAO 'finger in the air' categories and separations that most of the world still use.

I would not hold you breath, there is actually very little actual science in RECAT. RECAT is good for final approach segment, and perhaps the departure recat will come alive again.
The entire RECAT was based on 4 valid wake measurements out of Memphis....What has been known for years is that the wakes dont last as long as they state, and especially in even a light crosswinds, are out of the flightpath in around 20 seconds.
So the 'science' is just closing up the spacing until you have more wake encounters, then they will back it off. It does not take into account still air, or inversion layers, in reality, it is just sticking their finger up somewhere.(this is why they are studying 'acceptable' wake encounters.

Look at LHR. Doesnt everyone think there is a good possiblity of a wake encounter on final, and expect a wake encounter on dep? The reason there are not more serious incidents is that everyone expects it to happen.

The "beast of a wake" that underfire posted at #9 was from a 787.

Yes, the post was about how severe the wake is from the 787.

The 748 was required to do studies on wake as well as part of cert.

Capt Fathom
16th Nov 2018, 03:29
As the wake descends you shouldn’t encounter it when descending down the glideslope, notwithstanding aircraft that may be intercepting at a different altitudes.
Almost guaranteed as you approach the runway as the wake hits the ground and bounces back up. The last place you want an encounter!

B2N2
16th Nov 2018, 04:23
Hey ace,

This was published before the Challenger/A380 incident
https://ad.easa.europa.eu/blob/EASA_SIB_2017_10.pdf/SIB_2017-10_1

Some additional info here
https://ops.group/blog/tag/wake-turbulence/


https://www.skybrary.aero/index.php/Airbus_A380_Wake_Vortex_Guidance

Hawker 800
17th Nov 2018, 10:03
B2N2

the first EASA link was published after the incident actually.

Interestingly enough, SLOP was not permitted on that route during the time of the incident...

https://www.flightglobal.com/news/articles/a380-wake-upset-inquiry-offset-not-permitted-on-rou-437303/

ATCO’s in that area often warn me of the proximity of Super’s.

underfire
17th Nov 2018, 15:38
As the wake descends you shouldn’t encounter it when descending down the glideslope, notwithstanding aircraft that may be intercepting at a different altitudes.

The wake will also hang on inversion layers

Gonzo
21st Nov 2018, 02:38
I would not hold you breath, there is actually very little actual science in RECAT. RECAT is good for final approach segment, and perhaps the departure recat will come alive again.
The entire RECAT was based on 4 valid wake measurements out of Memphis....What has been known for years is that the wakes dont last as long as they state, and especially in even a light crosswinds, are out of the flightpath in around 20 seconds.
So the 'science' is just closing up the spacing until you have more wake encounters, then they will back it off. It does not take into account still air, or inversion layers, in reality, it is just sticking their finger up somewhere.(this is why they are studying 'acceptable' wake encounters.

Look at LHR. Doesnt everyone think there is a good possiblity of a wake encounter on final, and expect a wake encounter on dep? The reason there are not more serious incidents is that everyone expects it to happen.


Yes, the post was about how severe the wake is from the 787.

The 748 was required to do studies on wake as well as part of cert.

Are you talking about RECAT in the USA, or RECAT-EU which is different? And yes, RECAT-EU is only applied for intermediate and final approach spacing, and departure spacing at LHR. RECAT-EU is certainly based on far more measurements than just 4.

How does an encounter become less serious if the following flight crew expect it?

From most of the main LHR-based airlines we can get access to FDR data, from which one can extrapolate the force of the wake.

Gonzo
21st Nov 2018, 02:41
Just to be clear: is it being stated or claimed here Ė by those who are experienced in the game Ė that en route wake from a "super" A380 is worse, more to be avoided, than wake from a large "heavy" such as a 747-8 or a 787? The "beast of a wake" that underfire posted at #9 was from a 787.

Gonzo, can you briefly explain (for benefit of this small-aircraft pilot) about the forthcoming Static Pair Wise Separation?

Yes, instead of having a separation matrix of 4x4 categories, or 6x6 categories, you have a matrix of 96x96 aircraft types, where, depending upon your desired resolution (0.1nm, 0.25nm, 10sec, 20secs etc) each aircraft pairing can have its own separation.

For example, 747-400 followed by A320 might be 3.2nm, 747-400 followed by A319 might be 3.4nm, 747-400 followed by A321 might be 3.1nm. And so on......

underfire
21st Nov 2018, 14:29
I dont think the 96x96 will ever be used. ATC certainly wont figure that out. Currently working with Thales to add the separation matrix to the ATC system. This will work with the flow manager for arrival, and the departure manager. The system will adjust the flow manager to affect the frequency of the arrival based on wake conditions.This will work abck through the system to enroute.
On the screen, there are 2 features, a moving dot on the approach path for intercept target, and a cone behind each ac for the min wake separation. Interesting that US based the cone is one way and it is opposite for ICAO based, go figure.

How does an encounter become less serious if the following flight crew expect it?
When the crew is ready for it, the adventure is much less of an adventure. Higher thrust setting and according flap setting. LHR is a natural example with the ARR speeds higher than most. I feel that this at least minimizes the wake effect.

Interestingly enough, on Sunday, DEP from SEA, in A321, hit a hell of a wake at about 300 AGL. just after rotate, rolled left then right, bouncing the whole way.. about 2 mins behind A320 sharklet. Ac was all over the place.

Currently looking at a more refined definition of simply wingspan/weight, using wing loading, as I have seen very strong wakes from smaller ac. I am looking at weight and wing area, (not simply wingspan) and wing shape. As noted before, as an example, the variable upswept geometry of an ac like the 787...
As examples: Wing area loading
A380: MTOW/845 sq m is 680 kg/ sq m
B747: MTOW / 511 sq m is 652 kg/sq m
B789: MTOW/360 sq m is 705 kg/sq m
B757: MTOW/376 sq m is 678 kg/sq m

Gonzo
21st Nov 2018, 22:34
I dont think the 96x96 will ever be used. ATC certainly wont figure that out. Currently working with Thales to add the separation matrix to the ATC system. This will work with the flow manager for arrival, and the departure manager. The system will adjust the flow manager to affect the frequency of the arrival based on wake conditions.This will work abck through the system to enroute.
On the screen, there are 2 features, a moving dot on the approach path for intercept target, and a cone behind each ac for the min wake separation. Interesting that US based the cone is one way and it is opposite for ICAO based, go figure.


When the crew is ready for it, the adventure is much less of an adventure. Higher thrust setting and according flap setting. LHR is a natural example with the ARR speeds higher than most. I feel that this at least minimizes the wake effect.

Interestingly enough, on Sunday, DEP from SEA, in A321, hit a hell of a wake at about 300 AGL. just after rotate, rolled left then right, bouncing the whole way.. about 2 mins behind A320 sharklet. Ac was all over the place.

Currently looking at a more refined definition of simply wingspan/weight, using wing loading, as I have seen very strong wakes from smaller ac. I am looking at weight and wing area, (not simply wingspan) and wing shape. As noted before, as an example, the variable upswept geometry of an ac like the 787...
As examples: Wing area loading
A380: MTOW/845 sq m is 680 kg/ sq m
B747: MTOW / 511 sq m is 652 kg/sq m
B789: MTOW/360 sq m is 705 kg/sq m
B757: MTOW/376 sq m is 678 kg/sq m

Of course 96x96 will be used. Itís coming to LHR in the next few years.

Expectation might mean that correction is quicker and therefore requires less roll input, but the initial roll moment will still occur. Thatís what is measured.

LHR arrival speed is higher? Relative to what? 160kts to 4DME is not high in my opinion. For some of our types thatís too slow

misd-agin
22nd Nov 2018, 13:00
Of course 96x96 will be used. Itís coming to LHR in the next few years.

Expectation might mean that correction is quicker and therefore requires less roll input, but the initial roll moment will still occur. Thatís what is measured.

LHR arrival speed is higher? Relative to what? 160kts to 4DME is not high in my opinion. For some of our types thatís too slow




It can be tough to be stabilized at 160/4 DME on some flights.
For what types is 160 kts too slow?

misd-agin
22nd Nov 2018, 13:22
As examples: Wing area loading
A380: MTOW/845 sq m is 680 kg/ sq m
B747: MTOW / 511 sq m is 652 kg/sq m
B789: MTOW/360 sq m is 705 kg/sq m
B757: MTOW/376 sq m is 678 kg/sq m[/QUOTE]

Using Wikipedia as a source produced slightly different numbers -

A380 - 680/sq m
748 - 808/sq m
744 - 786/sq m
773 - 700 kg/sq m
789 - 674/sq m
763 - 660/sq m
752 - 624/sq m

Interesting that the 747 numbers are much higher than the others. Perhaps a mistake in wikiís data?

underfire
22nd Nov 2018, 14:49
Not sure which wiki data you are referencing.
https://en.wikipedia.org/wiki/Wing_loading
https://en.wikipedia.org/wiki/Boeing_747-8 (https://en.wikipedia.org/wiki/Wing_loading)

I did not use wiki data, that is not vetted and really should not be relied on.

Luftansa uses 511 sq m for 744 and 554 sq m for 748, I did not use 748 data as there are very few of these in service.
For the 787 series, there is a scientific paper on this aircraft.
A388 was from Airbus.
B773 was from Swiss Air. (427 sq m)

BTW, Airbus uses the center wing in their area calculations, Boeing does not. This may be why you will see such differences in similar ac, or why there are differences in the source on same ac.

This website seems to be a bit more accurate: http://www.flugzeuginfo.net/acdata_en.php (http://www.flugzeuginfo.net/acdata_php/acdata_7773_en.php)

Of course 96x96 will be used. It’s coming to LHR in the next few years.

I sincerely doubt this. I cannot see ATC sorting this many variants out, especially of the same ac variants. Aside from that, by the time this ill-fated scenario rolls out, there will be even more variants. (now it is a 115 by 115 matrix)
There is the potential to have something similar, if NATS gets the automation worked out on the new ATC system, but this would require the new system...lets see how that works out, and in how many years.

Interesting to note the RECAT pilot program at Memphis, no increase in REPORTED wake encounters...(no decrease either) I know every pilot reports every wake encounter, so it appears that RECAT works, right?

Curious, what is going on with time based separation at LHR?

160 at 4DME is fast. For the 320 and 737 variants, not an issue., but try to manage the energy of a large aircraft from 160 down to FAS from 4 DME. (and with steeper approaches?!?!) Most large ac the optimum GPA is 2.8 to manage the energy.

misd-agin
23rd Nov 2018, 03:47
Lufthansa and Swiss Airbus provide ďvettedĒ data?

I used a different source for the first aircraft I checked. I then switched to Wikipedia and they had the same wing area.

Most of the data that I use at work is very close, or exactly, what Wikipedia has for a lot of the data.

underfire
23rd Nov 2018, 13:43
Doesnt really matter, many of the sources use the same source, use whatever you want. I did not find the 808 sq m for the 747, nor the 680 sq m, that you found on wiki something. Wiki data is not really vetted, I can go up there and edit an entry with whatever I want, it relies on someone to review it, whenever they get around to it or there is a comment about the validity..

Luftansa does extensive studies on their ac, one of which provided the wing root data down the wing, which is what I use.
Same for the 787-9 and the Max data, scientific papers as submitted for the wake turbulence validations.

Again, some Airbus data includes the center wing area, so one has to be able to sort that out of the mix, so as to make a relative comparison with the other data.

Gonzo
25th Nov 2018, 08:45
It can be tough to be stabilized at 160/4 DME on some flights.
For what types is 160 kts too slow?

B77Ws are often given 165kts to 4DME.

Gonzo
25th Nov 2018, 08:56
I sincerely doubt this. I cannot see ATC sorting this many variants out, especially of the same ac variants. Aside from that, by the time this ill-fated scenario rolls out, there will be even more variants. (now it is a 115 by 115 matrix)
There is the potential to have something similar, if NATS gets the automation worked out on the new ATC system, but this would require the new system...lets see how that works out, and in how many years.

We already use variant-specific average speed profiles inside 4DME to calculate the anticipated compression between an aircraft pair, so we are already using a pair-wise modification of the RECAT distance which is already modified by TBS. What automation is required specifically for PWS? Itís just a case of having larger look up table of values. What do you mean by Ďsomething similar?

160 at 4DME is fast. For the 320 and 737 variants, not an issue., but try to manage the energy of a large aircraft from 160 down to FAS from 4 DME. (and with steeper approaches?!?!) Most large ac the optimum GPA is 2.8 to manage the energy.


A380s do 160 to 5DME.

Iím not aware of any comparable airport where they come down the whole final approach at 150 or 145, are you?

underfire
26th Nov 2018, 22:53
The 115 x 115 matrix, or RECAT 2, is based on having the ATC software system set up to manage it, especially much further up the queue.
When I stated similar, I meant the systems currently being worked on by Thales, NATS, or other similar ATC solution.
The whole Brexit thing really screwed up progress at LHR, we were virtually signing contracts to move forward, then poof, 3rd runway BS again.