Vortex Wake and the 757
Joined: Jul 2001
Posts: 62
Likes: 0
From: Home
Dear Burp
May I ask, are you interested in furthering safe and professinal air traffic or do you find being obstructive more exciting?
But, since you ask:
I recall your boasts that over in the tower you could accept traffic 2 miles apart down 23 on the basis that the strong wind made the interval comparable and safe. So I find myself asking, what are you really interested in here? The legitimacy of spacing? I think not.
I will happily engage in a debate with you about what we are doing here but I haven't got time for games of "oneupmanship".
May I ask, are you interested in furthering safe and professinal air traffic or do you find being obstructive more exciting?
But, since you ask:
I recall your boasts that over in the tower you could accept traffic 2 miles apart down 23 on the basis that the strong wind made the interval comparable and safe. So I find myself asking, what are you really interested in here? The legitimacy of spacing? I think not.
I will happily engage in a debate with you about what we are doing here but I haven't got time for games of "oneupmanship".
Joined: Jul 2001
Posts: 33
Likes: 0
From: WWW
Help me out here ...
Is it the UK CAA Air Nav Regs that recommends 1 min spacing or the UK MATS ..or does the UK MATS recommnedations get fully accepted by the CAA ANR's ?
Does the UK 1min then therefore supercede the ICAO recommendations? Is the recommended Wake Turb spacing separation minima freely available to pilots ...is it in the UK AIP ?
ICAO says two minutes should be applied ....and I feel it is the operators right to ask for extra spacing ...especially if what they ask for is the ICAO recommended minimum..not so ...
To be fair the operator should advise ATC prior to lining up what spacing they require....the guy/gal in the tower should not assume that 1 min will be accepted ..but should rather ask before committing themselves .....
Strange thing is, this is one of the few cases where it seems that the UK is less stringent than our US colleages ?? That's surely should say something ...I mean the US have been the instigators of reduced separations from the beginning of time ...put differently, I did not believe one could go any lower than the US minimas in anything ...they are already pushing the envelope far beyond what is reasonable
Is it the UK CAA Air Nav Regs that recommends 1 min spacing or the UK MATS ..or does the UK MATS recommnedations get fully accepted by the CAA ANR's ?
Does the UK 1min then therefore supercede the ICAO recommendations? Is the recommended Wake Turb spacing separation minima freely available to pilots ...is it in the UK AIP ?
ICAO says two minutes should be applied ....and I feel it is the operators right to ask for extra spacing ...especially if what they ask for is the ICAO recommended minimum..not so ...
To be fair the operator should advise ATC prior to lining up what spacing they require....the guy/gal in the tower should not assume that 1 min will be accepted ..but should rather ask before committing themselves .....
Strange thing is, this is one of the few cases where it seems that the UK is less stringent than our US colleages ?? That's surely should say something ...I mean the US have been the instigators of reduced separations from the beginning of time ...put differently, I did not believe one could go any lower than the US minimas in anything ...they are already pushing the envelope far beyond what is reasonable
Joined: Jul 2001
Posts: 76
Likes: 0
From: europe
I think the topic will be beaten to death if the debate continues as is...Before I go, to those of you who are involved in the operation of the awe inspiring enigma that is "A.T.C." AT EGLL be it APPROACH,DIRECTOR,TOWER,GROUND,or DELIVERY...I'm impressed to the point where I feel obliged to tell you all...
Joined: May 2001
Posts: 13
Likes: 0
Strength-5,
You'll probably find the answers to some of your questions here.....
http://www.ais.org.uk/Uk_aip/pdf/aic/4P188.pdf
TR3,
Sorry, will try and keep it relatively brief and make it my last word on the subject.
09L,
Apologies also that you seem to think I'm being obstructive. But if I cannot question methods/motives I'm not sure how I'm meant to form a valid opinion.
I'll take your word for it but I don't remember boasting to anybody about the above.
All I would mention is that depending what the combination of aircraft types involved is, there may not be any vortex wake spacing requirement. Then you'd only have to justify some method of reducing the radar separation, but I suppose that's a different arguement
I'll continue to position appropriate traffic 4nm behind the 757, because it would appear that the research done has led to that distance being an acceptable compromise. And when it comes down to it all wake vortex separation, like so many other factors in this business probably is just that, a compromise (see para 2.13.1 of the AIC mentioned above).
B.
Edited for out of control UBB code.
[ 03 August 2001: Message edited by: burp ]
You'll probably find the answers to some of your questions here.....
http://www.ais.org.uk/Uk_aip/pdf/aic/4P188.pdf
TR3,
Sorry, will try and keep it relatively brief and make it my last word on the subject.
09L,
Apologies also that you seem to think I'm being obstructive. But if I cannot question methods/motives I'm not sure how I'm meant to form a valid opinion.
I recall your boasts that over in the tower you could accept traffic 2 miles apart down 23 on the basis that the strong wind made the interval comparable and safe. So I find myself asking, what are you really interested in here? The legitimacy of spacing? I think not.
All I would mention is that depending what the combination of aircraft types involved is, there may not be any vortex wake spacing requirement. Then you'd only have to justify some method of reducing the radar separation, but I suppose that's a different arguement
I'll continue to position appropriate traffic 4nm behind the 757, because it would appear that the research done has led to that distance being an acceptable compromise. And when it comes down to it all wake vortex separation, like so many other factors in this business probably is just that, a compromise (see para 2.13.1 of the AIC mentioned above).
B.
Edited for out of control UBB code.
[ 03 August 2001: Message edited by: burp ]
Joined: Jul 2001
Posts: 33
Likes: 0
From: WWW
Tks Burp ..that was really informative ..nice to see how it is done/applied in the other neck of the woods cossack having just read burp's contribution ...I can't see where / how you get to apply 1 minute ...please explain ?
Thread Starter
Joined: Sep 2000
Posts: 535
Likes: 1
From: Toronto
Strength -5
The Upper Medium category only applies to arriving aircraft, so a departing 757 is considered a Medium by ATC and so can be followed 1 minute later by any aircraft that is either another Medium or a Small. OK?
It is in our instructions that some operators may require more than this "standard" and advises ATCOs to ask before line up that they will accept it. More and more carriers will not but many still do. This is where the confusion arises..
What is needed is a standard that everyone is happy to use. If that turns out to be 2 minutes then so be it, but until then we are still permitted to use 1 minute as I said above.
Categorising a 757 as a Heavy when its in front and a Medium when its behind (as in Oz) seems like a good compromise. It will of course mean a slight reduction in landing rates, but what price safety?
What is needed is harmonisation and standardisation, and soon.
The Upper Medium category only applies to arriving aircraft, so a departing 757 is considered a Medium by ATC and so can be followed 1 minute later by any aircraft that is either another Medium or a Small. OK?
It is in our instructions that some operators may require more than this "standard" and advises ATCOs to ask before line up that they will accept it. More and more carriers will not but many still do. This is where the confusion arises..
What is needed is a standard that everyone is happy to use. If that turns out to be 2 minutes then so be it, but until then we are still permitted to use 1 minute as I said above.
Categorising a 757 as a Heavy when its in front and a Medium when its behind (as in Oz) seems like a good compromise. It will of course mean a slight reduction in landing rates, but what price safety?
What is needed is harmonisation and standardisation, and soon.
Joined: Jul 2001
Posts: 33
Likes: 0
From: WWW
Tks Cossack ...
Ditto on the need for a standard ...don't feel alone ...there is a need for it worldwide ....
I will look through those docs again and see if I can find the 1 MIN thing ...time for new specs ...my "old" eyes ain't what they used to be ...
I too have bur'nt my fingers on many an occassion ...hence I also always ask if I not 100% sure ...saves having to sit on the edge of your seat ...with the mic clutched between your teeth like a bit on a bridle ...
Ditto on the need for a standard ...don't feel alone ...there is a need for it worldwide ....
I will look through those docs again and see if I can find the 1 MIN thing ...time for new specs ...my "old" eyes ain't what they used to be ...
I too have bur'nt my fingers on many an occassion ...hence I also always ask if I not 100% sure ...saves having to sit on the edge of your seat ...with the mic clutched between your teeth like a bit on a bridle ...
Joined: Jul 2001
Posts: 62
Likes: 0
From: Home
I agree too Cossack. The OZ idea seems to be a good one. As Burp said earlier, the number of 75s is reducing, so the impact would be minimal and as you say, 'what price safety?'.
Are there any particular airlines that ask for 2 mins or is it just individual crews? I find that crews are becoming much more helpful in advising us of unusual things. Many 75s pipe up if they are going to be particularly slow inside 4 and more and more 73s are asking early for 170kts down to 4.
[ 05 August 2001: Message edited by: ZeroNine Left ]
Are there any particular airlines that ask for 2 mins or is it just individual crews? I find that crews are becoming much more helpful in advising us of unusual things. Many 75s pipe up if they are going to be particularly slow inside 4 and more and more 73s are asking early for 170kts down to 4.
[ 05 August 2001: Message edited by: ZeroNine Left ]
Thread Starter
Joined: Sep 2000
Posts: 535
Likes: 1
From: Toronto
I think many airlines (certainly Eurpoean carriers) now have the 2 minutes as a standard, but some will, if asked, take a reduction if the wind is favourable.
It also states in the AIP link that the 2 minutes is a rotation to rotation time. So you will be cleared for take of after between 70 and 90 seconds depending on how long we think your take off roll will be.
How many times have you been asked for another 20 seconds and you end up with a gap of 2.20?
That's something else that differs. In the US the time interval is from start of roll to start of roll. Lots of room for less than 2 minutes there.
It also states in the AIP link that the 2 minutes is a rotation to rotation time. So you will be cleared for take of after between 70 and 90 seconds depending on how long we think your take off roll will be.
How many times have you been asked for another 20 seconds and you end up with a gap of 2.20?
That's something else that differs. In the US the time interval is from start of roll to start of roll. Lots of room for less than 2 minutes there.
Thread Starter
Joined: Sep 2000
Posts: 535
Likes: 1
From: Toronto
CHIRP Feedback 60 contains information on this subject.
It is interesting to note that there have been no reports of vortex wake encounters on departure in the UK. Is this because there is no problem or is it because of the fairly widespread use of a 2 minute departure interval?
It is interesting to note that there have been no reports of vortex wake encounters on departure in the UK. Is this because there is no problem or is it because of the fairly widespread use of a 2 minute departure interval?
Thread Starter
Joined: Sep 2000
Posts: 535
Likes: 1
From: Toronto
Do any Heathrow people have any comments?
I know we're obliged to ask if they'll accept 1 minute but what do you expect traffic following a 757 to do?
Should we standardise like OZ, Heavy if leading, Medium if following?
I know we're obliged to ask if they'll accept 1 minute but what do you expect traffic following a 757 to do?
Should we standardise like OZ, Heavy if leading, Medium if following?
