Vortex Wake and the 757
Joined: Jul 2001
Posts: 76
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From: europe
COSSACK...The guys have a point, sometimes departing behind a B757...or...following one on approach can be an interesting experience . For us the cutoff is the defined 136,000kgs making an exception for the B757,generally, as one makes their way out for departure at LHR and the subject a/c is departing ahead, I would endevour to advise ATC of the 2 mins or even 3 if using B16 or B79,sometimes I've felt the lash of ATC's razor tongue but that a/c does churn up the air a lot ...Please fogive us our...
Joined: May 2001
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09L,
We can only play by the rules given to us.
If everyone decided to fudge them to their own personal criteria, where would that leave us? Be a bit of a shambles I suspect.
You don't happen to tell every aircraft that is following a heavy that superfluous piece of info as well do you?
Burp.
We can only play by the rules given to us.
If everyone decided to fudge them to their own personal criteria, where would that leave us? Be a bit of a shambles I suspect.
You don't happen to tell every aircraft that is following a heavy that superfluous piece of info as well do you?
Burp.
Joined: Jul 2001
Posts: 62
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From: Home
Well Burp, appropriate handle!
Correct, and the rules permit any controller to increase separation when they deem it fit. For example, following an aircraft type such as the 75 that is known to produce more vortex than expected from its weight and which has caused many vortex incidents. Safety before movements doesn't seem unreasonable to me.
Superfluous? Well, wake vortex is unpredictable. With your time in the job you will have had traffic behind a heavy get into a vortex problem at some stage, even when he's comforably over the prescribed minimum. It seems to me that to give the guy a warning that he is following one would be a most professional thing to do; and that is what we are about here isn't it?... professional ATC?
Here's a piece of superfluous info. for you: A tree is in one of two states; it is either growing or it is dead. Now if all human beings were open to growth the world would progress. That would be nice, wouldn't it?
Night night
Correct, and the rules permit any controller to increase separation when they deem it fit. For example, following an aircraft type such as the 75 that is known to produce more vortex than expected from its weight and which has caused many vortex incidents. Safety before movements doesn't seem unreasonable to me.
Superfluous? Well, wake vortex is unpredictable. With your time in the job you will have had traffic behind a heavy get into a vortex problem at some stage, even when he's comforably over the prescribed minimum. It seems to me that to give the guy a warning that he is following one would be a most professional thing to do; and that is what we are about here isn't it?... professional ATC?
Here's a piece of superfluous info. for you: A tree is in one of two states; it is either growing or it is dead. Now if all human beings were open to growth the world would progress. That would be nice, wouldn't it?
Night night
Thread Starter
Joined: Sep 2000
Posts: 535
Likes: 1
From: Toronto
A Slim Shady
You have just re-inforced the point I was making in my first post. If pilots consider the 757 to be a heavy if they are following it, but not if they are in it, it opens up a can of worms where ATC don't know what the separation should be because its all at the discretion of the following pilots or their company.
09L
I'm not suggesting a 757 go 1 minute behind a 777 but there has to be a laid down procedure for this as in the US. We are, like it or not, under commercial pressure to move aircraft at a contracted rate to and from our runways. As burp implies, if every pilot wants another 30 seconds or a minute before departure or you provide and extra half mile on every gap because you think it appropriate, I think you will soon find that targets are not being met and BAA or whoever will want to know why.
TR3
Is it less safe to depart 1 minute behind a 757 than 2?
I don't know, but there are people in offices paid to make these rules on the basis on research and fact. They have said that you can depart 1 minute behind a 757 so 1 minute it is. If you want/need more, tell us early, it may mean you depart before the 757.
In 14 years of controlling I have not yet been notified of any wake vortex incidents from aircraft under my control. Are pilots keeping quiet or just no incidents to report? I do pass type and distance of preceding traffic when separated by the minimum, maybe that helps I don't know.
Until the rules are modified I will continue to use the separations laid down.
Once again, if you want more than the ATC prescribed minimum time before departure, tell us early.
You have just re-inforced the point I was making in my first post. If pilots consider the 757 to be a heavy if they are following it, but not if they are in it, it opens up a can of worms where ATC don't know what the separation should be because its all at the discretion of the following pilots or their company.
09L
I'm not suggesting a 757 go 1 minute behind a 777 but there has to be a laid down procedure for this as in the US. We are, like it or not, under commercial pressure to move aircraft at a contracted rate to and from our runways. As burp implies, if every pilot wants another 30 seconds or a minute before departure or you provide and extra half mile on every gap because you think it appropriate, I think you will soon find that targets are not being met and BAA or whoever will want to know why.
TR3
Is it less safe to depart 1 minute behind a 757 than 2?
I don't know, but there are people in offices paid to make these rules on the basis on research and fact. They have said that you can depart 1 minute behind a 757 so 1 minute it is. If you want/need more, tell us early, it may mean you depart before the 757.
In 14 years of controlling I have not yet been notified of any wake vortex incidents from aircraft under my control. Are pilots keeping quiet or just no incidents to report? I do pass type and distance of preceding traffic when separated by the minimum, maybe that helps I don't know.
Until the rules are modified I will continue to use the separations laid down.
Once again, if you want more than the ATC prescribed minimum time before departure, tell us early.
Controversial, moi?
Joined: Oct 2000
Posts: 1,622
Likes: 22
From: UK
Also on the subject of wake. When I was completing my command training we landed at LHR on 27R with a very light tailwind from the rear right hand quarter. The training captain then related a story to me of landing in a similar situation with nother command trainee where the preceding aircraft's wake had been blown back to the threshold/landing area. He said that it was very exciting during the flare!
Sme months later it happened to me in not quite so dramatic a fashion but noticeable.
Apologies if I am preaching to the converted but something to bear in mind.
Sme months later it happened to me in not quite so dramatic a fashion but noticeable.
Apologies if I am preaching to the converted but something to bear in mind.
Joined: May 2001
Posts: 13
Likes: 0
09L,
You may recall that the Upper Medium group was introduced to cater primarily for the 757. This following a fair amount of study into the subject.
If you now have some non anecdotal evidence that the spacing should be increased even further, I'd be very pleased to hear it.
In the meantime, I'll just carry on applying the recommended spacing. Perhaps the only saving grace here is that the number of 757's operating into EGLL is gradually reducing.
Thanks for the philosophy lesson
Burp.
You may recall that the Upper Medium group was introduced to cater primarily for the 757. This following a fair amount of study into the subject.
If you now have some non anecdotal evidence that the spacing should be increased even further, I'd be very pleased to hear it.
In the meantime, I'll just carry on applying the recommended spacing. Perhaps the only saving grace here is that the number of 757's operating into EGLL is gradually reducing.
Thanks for the philosophy lesson
Burp.
Joined: Jul 2001
Posts: 62
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From: Home
Cossack
Sorry, I may have misunderstood you! I wouldn't suggest a 75 goes 1 min behind a 777 either!! But with respect, I cannot agree about the contracted rate. We declare a cpacity which we would expect to meet, all other things being equal but we are not contracted to that (well not at LL anyway). Sometimes, in ideal conditions, we smash that rate and at other times we don't get near it. I guess what I am trying to say is I don't believe any individual should feel that they HAVE to make targets. That will just lead us further into this "push it" culture which will get people into trouble, particularly the less experienced.
As far as the 75 is concerned, it is not just the high vortex, the darned thing is also very slow on short final; yes, I add a bit on behind but a take a bit off in front and that way you don't find 73s only 3 miles behind it as it touches down. Safety is enhanced but the landing rate doesn't change. I think that is a reasonable and professional way to go about it.
As far as BAA are concerned: We all know that the runways are oversubscribed and that there is no spare left to cater for problems but that isn't our problem. It is not our job to make up for the unwillingness of government/BAA to provide the runway capacity that we need. Our primary task is safety and if on a still morning when 76s are being bumped around by 75s then it is unwise to remain stuck to the rules. "...the obedience of fools etc..."
Burp. No, as I am sure you know, I connot give non-anecdotal evidence of the 75s nature but I can point you to the evidence on this forum and that found in other countries such as the US, Germany and Holland. You are of course quite entitled to take the stance you do and nobody could criticise you for it but what is more important, the words of the rule or the spirit it enshrines? Are we forbidden to use our common sense? If we know that what is written doesn't really suffice aren't we honour bound to address that?
Thanks for listening.
[ 01 August 2001: Message edited by: ZeroNine Left ]
[ 01 August 2001: Message edited by: ZeroNine Left ]
Sorry, I may have misunderstood you! I wouldn't suggest a 75 goes 1 min behind a 777 either!! But with respect, I cannot agree about the contracted rate. We declare a cpacity which we would expect to meet, all other things being equal but we are not contracted to that (well not at LL anyway). Sometimes, in ideal conditions, we smash that rate and at other times we don't get near it. I guess what I am trying to say is I don't believe any individual should feel that they HAVE to make targets. That will just lead us further into this "push it" culture which will get people into trouble, particularly the less experienced.
As far as the 75 is concerned, it is not just the high vortex, the darned thing is also very slow on short final; yes, I add a bit on behind but a take a bit off in front and that way you don't find 73s only 3 miles behind it as it touches down. Safety is enhanced but the landing rate doesn't change. I think that is a reasonable and professional way to go about it.
As far as BAA are concerned: We all know that the runways are oversubscribed and that there is no spare left to cater for problems but that isn't our problem. It is not our job to make up for the unwillingness of government/BAA to provide the runway capacity that we need. Our primary task is safety and if on a still morning when 76s are being bumped around by 75s then it is unwise to remain stuck to the rules. "...the obedience of fools etc..."
Burp. No, as I am sure you know, I connot give non-anecdotal evidence of the 75s nature but I can point you to the evidence on this forum and that found in other countries such as the US, Germany and Holland. You are of course quite entitled to take the stance you do and nobody could criticise you for it but what is more important, the words of the rule or the spirit it enshrines? Are we forbidden to use our common sense? If we know that what is written doesn't really suffice aren't we honour bound to address that?
Thanks for listening.
[ 01 August 2001: Message edited by: ZeroNine Left ]
[ 01 August 2001: Message edited by: ZeroNine Left ]
Joined: Jan 2001
Posts: 222
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From: The world's biggest beach
TR3 and any other EGLL pilots.
I and many of my colleagues promise not to give you a lashing with our tongues (fnarfnarf) if you want more than the prescribed minima, but please tell us before we give the runway to you
I and many of my colleagues promise not to give you a lashing with our tongues (fnarfnarf) if you want more than the prescribed minima, but please tell us before we give the runway to you
Thread Starter
Joined: Sep 2000
Posts: 535
Likes: 1
From: Toronto
What a lively debate!
09L
What would happen at TC if one day a Heathrow Director (not the HEATHROW DIRECTOR obviously
) was feeling a bit off and decided that they would add a bit, say a mile, to every gap?
Answer: The holds would fill up, the achieved landing rate would be looked at, the reasons for it would be sought and said Director would probably be asked to pull the finger out or be replaced.
What I am trying to discover here is, is the recommended spacing still appropriate? If it is we should all be willing to use it. If it is not, then the powers that be need to do some more work and find spacing requirements for both arivals and departures that ATC and airlines are happy to accept and then any confusion is removed.
I'm all for using common sense, but common sense, or the lack of it, varies from person to person. We should have a system that works well in normal day to day use without the necessity to resort to common sense. It is just another variable.
There's obviously something wrong with what is happening at the moment because different countries have different rules for the same problem. Who is right? No wonder pilots get confused. Is it 4 miles, 2 minutes or will 1 do?
09L
What would happen at TC if one day a Heathrow Director (not the HEATHROW DIRECTOR obviously
) was feeling a bit off and decided that they would add a bit, say a mile, to every gap?Answer: The holds would fill up, the achieved landing rate would be looked at, the reasons for it would be sought and said Director would probably be asked to pull the finger out or be replaced.
What I am trying to discover here is, is the recommended spacing still appropriate? If it is we should all be willing to use it. If it is not, then the powers that be need to do some more work and find spacing requirements for both arivals and departures that ATC and airlines are happy to accept and then any confusion is removed.
I'm all for using common sense, but common sense, or the lack of it, varies from person to person. We should have a system that works well in normal day to day use without the necessity to resort to common sense. It is just another variable.
There's obviously something wrong with what is happening at the moment because different countries have different rules for the same problem. Who is right? No wonder pilots get confused. Is it 4 miles, 2 minutes or will 1 do?
Joined: Jul 2001
Posts: 62
Likes: 0
From: Home
Morning Cossack
Yes, it's a great debate, enjoying this one.
I completely agree that the system does need to be standardised because a KLM will come onto the frequency and insist on 5 miles if he is put behind a 75, because of his national law, when everybody else has to take 4. Also, this level of anecdotal evidence is quite sufficient to tell me that this needs to be looked at. How should we go about starting that?
A couple of other things: at LL, unless there is no headwind, the holds are full for a significant part of the day anyway.
We have a PC which constantly monitors the landing rate, giving us a reading for each of the last quarter hours and predicting, on the basis of the last 6 landers, what we should achieve in the hour. It helps the traffic manager with flow.
As far as spacing is concerned; well firstly, THE Heathrow Director never has an off day, he is always on top form! But there is a lot of bu*****t about LL and how perfect everything and everybody is. The truth is that it isn't like that. It does happen that sometimes you don't feel like packing 'em in and you don't. I have seen even "the best" doing that but I have also seen the same people breaking wake vortex spacing in a misguided effort to reduce delays. A quarter mile or so and not corrected, even on still days.
A senior manager said to me about 3 years ago that one of his worries was that the LL team clearly felt they HAD to land huge numbers all the time and that exposed them to error. It is not our job to make up for capacity shortages and every time we try we take pressure off other people to do what they should do.
[ 02 August 2001: Message edited by: ZeroNine Left ]
Yes, it's a great debate, enjoying this one.
I completely agree that the system does need to be standardised because a KLM will come onto the frequency and insist on 5 miles if he is put behind a 75, because of his national law, when everybody else has to take 4. Also, this level of anecdotal evidence is quite sufficient to tell me that this needs to be looked at. How should we go about starting that?
A couple of other things: at LL, unless there is no headwind, the holds are full for a significant part of the day anyway.
We have a PC which constantly monitors the landing rate, giving us a reading for each of the last quarter hours and predicting, on the basis of the last 6 landers, what we should achieve in the hour. It helps the traffic manager with flow.
As far as spacing is concerned; well firstly, THE Heathrow Director never has an off day, he is always on top form! But there is a lot of bu*****t about LL and how perfect everything and everybody is. The truth is that it isn't like that. It does happen that sometimes you don't feel like packing 'em in and you don't. I have seen even "the best" doing that but I have also seen the same people breaking wake vortex spacing in a misguided effort to reduce delays. A quarter mile or so and not corrected, even on still days.
A senior manager said to me about 3 years ago that one of his worries was that the LL team clearly felt they HAD to land huge numbers all the time and that exposed them to error. It is not our job to make up for capacity shortages and every time we try we take pressure off other people to do what they should do.
[ 02 August 2001: Message edited by: ZeroNine Left ]
Thread Starter
Joined: Sep 2000
Posts: 535
Likes: 1
From: Toronto
09L
We have the same readout on our EAT machine too. Interesting reading somedays! We can see how you, Gatwick, Stansted and Luton are getting on too.
As for starting a review, I guess its a word in Unit Management's ear and take it from there. Maybe the powers that be read this. You can only hope.
There is no doubt there is pressure to perform to the best all the time, but this pressure has to be tempered with knowing that what you are doing is safe in everybody's mind, not just your own.
We have the same readout on our EAT machine too. Interesting reading somedays! We can see how you, Gatwick, Stansted and Luton are getting on too.
As for starting a review, I guess its a word in Unit Management's ear and take it from there. Maybe the powers that be read this. You can only hope.
There is no doubt there is pressure to perform to the best all the time, but this pressure has to be tempered with knowing that what you are doing is safe in everybody's mind, not just your own.
Joined: Jul 2001
Posts: 62
Likes: 0
From: Home
Spot on!
I had no idea we were national viewing!
Have you been to have a look at FAST? BIG debate going on here about it. We won't need it until we get to time based separation but SASS would be a real benefit now, making the job much easier and it should shorten training times too.
How are you for staff up there?
I had no idea we were national viewing!
Have you been to have a look at FAST? BIG debate going on here about it. We won't need it until we get to time based separation but SASS would be a real benefit now, making the job much easier and it should shorten training times too.
How are you for staff up there?
Thread Starter
Joined: Sep 2000
Posts: 535
Likes: 1
From: Toronto
I saw a FAST demo at the ATMDC a couple of years ago. Won't it take the "skill" out of it a bit?
When you get a "quiet" few minutes I'm sure someone will let you see how we're doing to! Up to 36/hr yesterday on westerlies with all those crossers! The departures were a bit slack though!
When you get a "quiet" few minutes I'm sure someone will let you see how we're doing to! Up to 36/hr yesterday on westerlies with all those crossers! The departures were a bit slack though!
Joined: May 2001
Posts: 13
Likes: 0
09L,
I'm intrigued a little by the above. You increase separation behind the 757 but reduce it in front. Do you only do this when you've agreed 2.5nm separation with the tower in advance or would you do it anyway because it is another of your own rules?
I honestly have to say that no KLM has ever asked me for increased spacing behind a 757. They used to ask all the time on departure when I did the tower, but never on arrival.
Our senior manager must have been very worried, especially as every year for the last three years the declared capacity has gone up
B.
As far as the 75 is concerned, it is not just the high vortex, the darned thing is also very slow on short final; yes, I add a bit on behind but a take a bit off in front and that way you don't find 73s only 3 miles behind it as it touches down. Safety is enhanced but the landing rate doesn't change. I think that is a reasonable and professional way to go about it.
I honestly have to say that no KLM has ever asked me for increased spacing behind a 757. They used to ask all the time on departure when I did the tower, but never on arrival.
Our senior manager must have been very worried, especially as every year for the last three years the declared capacity has gone up
B.
