How to manufacture a Mid-Air.
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How to manufacture a Mid-Air.
This business spends millions of dollars, and man-hours, keeping aircraft from bumping into one another and then, thanks to RVSM and Nav equipment that works in inches - we get this. If they’d ‘bumped’, and they don’t come closer than this, how would it be explained to the man in the street who has a rough idea of the area of the North Atlantic?
2 OCT 2000.
UK AIRPROX/AAIB SERIOUS INCIDENT. A340 and A330 in Oceanic airspace at RVSM levels at N5828 W1646 at FL370.
Severe turbulence encounter. The A330 pilot reported that, as his aircraft was overtaking the A340, which was 1000ft below and slightly left, he observed the wings of the A340 starting to bounce as it hit turbulence. A330 then hit turbulence and received a TCAS RA ‘climb’ as altimeter showed 36,800ft. The A340 was then seen to climb rapidly and pass within 200 metres of the A330 to a level 1100ft above it. The A330 pilot then turned right to allow the A340 to return to its original flight level of FL360.
[This message has been edited by forget (edited 28 November 2000).]
2 OCT 2000.
UK AIRPROX/AAIB SERIOUS INCIDENT. A340 and A330 in Oceanic airspace at RVSM levels at N5828 W1646 at FL370.
Severe turbulence encounter. The A330 pilot reported that, as his aircraft was overtaking the A340, which was 1000ft below and slightly left, he observed the wings of the A340 starting to bounce as it hit turbulence. A330 then hit turbulence and received a TCAS RA ‘climb’ as altimeter showed 36,800ft. The A340 was then seen to climb rapidly and pass within 200 metres of the A330 to a level 1100ft above it. The A330 pilot then turned right to allow the A340 to return to its original flight level of FL360.
[This message has been edited by forget (edited 28 November 2000).]
Pegase Driver
Now you understand why it is agood idea to offset (up to 2NM is allowed in NAT /RVSM airspace ) and why after all this time the whole thing is still under TRIAL...
RVSM and CAT do not mix well. We said this since the begining.
RVSM and CAT do not mix well. We said this since the begining.
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All looks good for RVSM in Europe 2002....of course this is why Eurocontrol are trying to press ahead with 'Free Route'. This is the concept of filing a flight plan which is essentially a direct track from dep to dest. Minor route adjustments sent via datalink when conflicts arise. Sounds easy but expected delays due software lagging behind the actual idea, plus results not received from VHF datalink trials (I think they have started now)
Not sure if Free Route is planned for NAT though.
I once read an early document from a Eurocontrol think-tank which outlined their 10-15 year plan....it showed a potential system where these route adjustments were filtered through the airline ops and then passed to a/c. Just something to help everyone sleep better at night....
mm
Not sure if Free Route is planned for NAT though.
I once read an early document from a Eurocontrol think-tank which outlined their 10-15 year plan....it showed a potential system where these route adjustments were filtered through the airline ops and then passed to a/c. Just something to help everyone sleep better at night....
mm
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Your words are a sound for sore ears ATC Watcher - I'd appreciate any reference you have in regard to the allowable offset to arm myself for the next soul who criticises my mile to the right.
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This sort of thing will become more common. There is disconcerting confidence in the ability of technology to solve all humanity's problems. Air Traffic Control Authorities place increasing reliance on new technology to overcome congestion. We have already had 8.33 KHz VHF reducing the radio band seperation to just one third of human audio perception. Basic RNAV reduces track errors to within one mile while RVSM reduces vertical seperation to 1000 feet above FL290. These were all imposed as legal requirements before the necessary avionic equipment was designed, tested and certified in older aircraft. The belief seems to be that anything can be achieved as long as it is made mandatory. The TCAS experiment continues and I use the word experiment advisedly. (For those familiar with the technical side, consider the messy 'Gilham Code' AD focussed on analogue/digital conversion of altitude data for use in TCAS systems on non-digital aircraft.) EUROCONTROL will soon announce the introduction of rules to make RNP1/3 mandatory. ATC watcher's offset will be no use then, anything more than 750 metres will put you in the opposite lane as it were!
Is the equipment capable of these degrees of accuracy? I don't know and nor does anyone else. Although new deliveries of the latest models come ready equipped with the latest technology, most aircraft need major retrofit modifications. Not everyone has GPS (not as foolproof as many people think it is!) SatCom, ACARS or the latest Laser INUs capable of meeting the tighter RNP limits. Although equipment is already available and flight testing has been conducted on new built aircraft, long term equipment reliablity at the increased accuracy levels has never been established. Yet legal requirements will be imposed regardless, and in general by authorities that have no expertise in the details of installing and testing the systems.
The US Congress forced TCAS on the aviation world in the face of protests from avionic experts that equipment development would take more time. They have a lot to answer for now that they have established a trend.
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Is the equipment capable of these degrees of accuracy? I don't know and nor does anyone else. Although new deliveries of the latest models come ready equipped with the latest technology, most aircraft need major retrofit modifications. Not everyone has GPS (not as foolproof as many people think it is!) SatCom, ACARS or the latest Laser INUs capable of meeting the tighter RNP limits. Although equipment is already available and flight testing has been conducted on new built aircraft, long term equipment reliablity at the increased accuracy levels has never been established. Yet legal requirements will be imposed regardless, and in general by authorities that have no expertise in the details of installing and testing the systems.
The US Congress forced TCAS on the aviation world in the face of protests from avionic experts that equipment development would take more time. They have a lot to answer for now that they have established a trend.
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Through difficulties to the cinema
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Since I first started pushing this particular barrow, (up a seemingly very step hill), I've never ceased to be amazed at the resistance by fellow pilots, (as well as the perhaps mre understandable resistance by ATC and regulatory authorities), to this oh so simply achievable quantum leap in flight safety.
4holer, you give me heart to learn that I'm not the only one out there offsetting. The only way it's ever going to instituted in legslation is if so many people start doing it the powers that be simply can't ignore it.
4holer, you give me heart to learn that I'm not the only one out there offsetting. The only way it's ever going to instituted in legslation is if so many people start doing it the powers that be simply can't ignore it.
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Dream on, 410. Most pilots have a resistance to change that would put the Vatican to shame. Even if it was to be made compulsory, there'd be some who'd simply refuse to do it or offset one mile left just to be different.(!)
I've had a conversation on this subject with a mate in Australian CASA and he assures me the mathmeticians have proven to him that offsetting INCREASES the chances of collision. Something about having to re-draw the existing airways' dimensions to allow for it.
Can't see it myself, but there you go...
I've had a conversation on this subject with a mate in Australian CASA and he assures me the mathmeticians have proven to him that offsetting INCREASES the chances of collision. Something about having to re-draw the existing airways' dimensions to allow for it.
Can't see it myself, but there you go...
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The "offset" topic comes back once in a while. It seems like a good idea. Were there any studies conducted to formally evaluate the merits/demerits of offsetting (say 1 nm to the right on en-route)?
7X7 - how was your friends convinced? What were the assumptions the mathematicians were making?
I would appreciate any references (on both the questions above).
7X7 - how was your friends convinced? What were the assumptions the mathematicians were making?
I would appreciate any references (on both the questions above).
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Yeah, I've also heard the mathematicians "prove" that an offset makes things more dangerous. All I can say is that it gives me a warm fuzzy feeling when boring through the dark African skies to see the opposing traffic slide past a few miles off to the left, rather than straight down the centreline.
I'm sure the above-mentioned maths boffs all have IQs greater than 200 - pity they can't see the practical side of things sometimes!!
I'm sure the above-mentioned maths boffs all have IQs greater than 200 - pity they can't see the practical side of things sometimes!!
Pegase Driver
Quick replies :
4 holer : the ref is in ICAO RVSM trial procedures for NAT . It allows pilots to offset 2 NM to the right without having to advise ATC . But only valid in that airspace for the RVSM levels currently used (not all yet )
Moody : The Free Route Airpace Concept (FRAC) will be initially limited to 8 States ( Scandinavia + Benelux + Germany ) so definitively not in NAT and above FL 285 or 295. No data link in FRAC, only todays avionics . Feasibility depends on large scale simulations to be held in Bretigny (F) next year. Basically is to officialise in daytime what we already do during night.
410 : keep the faith..
4 holer : the ref is in ICAO RVSM trial procedures for NAT . It allows pilots to offset 2 NM to the right without having to advise ATC . But only valid in that airspace for the RVSM levels currently used (not all yet )
Moody : The Free Route Airpace Concept (FRAC) will be initially limited to 8 States ( Scandinavia + Benelux + Germany ) so definitively not in NAT and above FL 285 or 295. No data link in FRAC, only todays avionics . Feasibility depends on large scale simulations to be held in Bretigny (F) next year. Basically is to officialise in daytime what we already do during night.
410 : keep the faith..
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The maths is definitely correct. It is also total bunkum.
The ATC structures with the wherewithal to employ or contract these boffins are the large busy ones such as LATCC, Eurocontrol, Rhine Etc. They also end up with the power delegations at the conferences and meetings that review theses things. Their research is the only research and as such their findings are accepted as correct for all airspace.
Because of their own interests they, quite understandably, look at extremely complex airspace, for example around FFM. Through flights, multiple airports, climbing and descending traffic all enter the equations.
They totally ignore the encounter time of the vast majority of air transport traffic spending the vast majority of its flying hours sitting in the damn cruise on a standard five mile airway well away from their intellectually stimulating little hot spots.
These potherbs need to spend some time on a flight deck somewhere over the surface of planet reality. A planet with mindboggling amounts of silent, empty upper airspace while all the traffic flies frighteningly accurately through the eye of a needle (thanks to mathematicians).
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Regards from the Towers
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[This message has been edited by PPRuNe Towers (edited 26 November 2000).]
The ATC structures with the wherewithal to employ or contract these boffins are the large busy ones such as LATCC, Eurocontrol, Rhine Etc. They also end up with the power delegations at the conferences and meetings that review theses things. Their research is the only research and as such their findings are accepted as correct for all airspace.
Because of their own interests they, quite understandably, look at extremely complex airspace, for example around FFM. Through flights, multiple airports, climbing and descending traffic all enter the equations.
They totally ignore the encounter time of the vast majority of air transport traffic spending the vast majority of its flying hours sitting in the damn cruise on a standard five mile airway well away from their intellectually stimulating little hot spots.
These potherbs need to spend some time on a flight deck somewhere over the surface of planet reality. A planet with mindboggling amounts of silent, empty upper airspace while all the traffic flies frighteningly accurately through the eye of a needle (thanks to mathematicians).
------------------
Regards from the Towers
[email protected]
[This message has been edited by PPRuNe Towers (edited 26 November 2000).]
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Offsetting-An ATC perspective
In radar airspace. I think it very much a bad idea. Your 1 or 2nm offset may infact put you in conflict with another route. The controller is expecting you to fly a particular track and makes judgements based on your predicted track only to find you a mile or so closer to that other aircraft that you were going to slide nicely 5nm past.
Outside radar coverage:-
Not such a bad idea. Especially in areas where you don't particulary trust ATC. But here are some things for ADS/CPDLC aircraft to consider (Australian airspace)
i) When you fly an offset it is immediately known to ATC. Personally I don't give a hoot. The current rules do not allow me to ignore the fact that you are flying an offset
and because I know you are flying an offset I have to take that into consideration when working out seperation problems and this adds considerable complexity and delays to the calculation.
ii) When flying an offset the data from your ADS does not automatically update the data into the ATC computer as it would if you are flying on the route (because you are not on track it doesn't recognise that you have over flown any waypoints). You will probably be asked to give CPDLC positions.
A Singapore Airlines pilot told be the other day that it was company policy to fly an offset. Is this an official policy or just a policy of the pilots or was he telling me porkies?
Another pilot the other day was complaining to a colleague about not being able to get a particular level despite him being about 10nm away (outside radar coverage). He said that his GPS was accurrate to 50m and why should he be held up. My colleague's response was "So you would be happy to have another aircraft 50m from you?" This shut him up but I thought it was an interesting question. Just how close are you prepared to have another aircraft from you. Pilots often complain when they can't have what they want, but the line has to be drawn somewhere!
In radar airspace. I think it very much a bad idea. Your 1 or 2nm offset may infact put you in conflict with another route. The controller is expecting you to fly a particular track and makes judgements based on your predicted track only to find you a mile or so closer to that other aircraft that you were going to slide nicely 5nm past.
Outside radar coverage:-
Not such a bad idea. Especially in areas where you don't particulary trust ATC. But here are some things for ADS/CPDLC aircraft to consider (Australian airspace)
i) When you fly an offset it is immediately known to ATC. Personally I don't give a hoot. The current rules do not allow me to ignore the fact that you are flying an offset
and because I know you are flying an offset I have to take that into consideration when working out seperation problems and this adds considerable complexity and delays to the calculation.
ii) When flying an offset the data from your ADS does not automatically update the data into the ATC computer as it would if you are flying on the route (because you are not on track it doesn't recognise that you have over flown any waypoints). You will probably be asked to give CPDLC positions.
A Singapore Airlines pilot told be the other day that it was company policy to fly an offset. Is this an official policy or just a policy of the pilots or was he telling me porkies?
Another pilot the other day was complaining to a colleague about not being able to get a particular level despite him being about 10nm away (outside radar coverage). He said that his GPS was accurrate to 50m and why should he be held up. My colleague's response was "So you would be happy to have another aircraft 50m from you?" This shut him up but I thought it was an interesting question. Just how close are you prepared to have another aircraft from you. Pilots often complain when they can't have what they want, but the line has to be drawn somewhere!
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It’s interesting to see that this ‘incident' is to be investigated by the UK Air Accidents Investigation Branch. Rarely does this happen unless an incident is considered to be a gnats away from a disaster. No doubt the AAIB will produce a highly detailed investigation. Even now, they may be pondering the ‘procedures’ by which two air-liners can be deliberately brought within spitting distance of one another – and over the ocean. Granted that off-set track isn’t part of the equation when aircraft are pointing the same way - but RVSM! – we’ll live to rue the day.
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willadvise,
You don't have to be around these forums to realise the immense respect we have for our colleagues in ATC. However, your post uses all the reasoning that fills so many of us with dread.
To your way of thinking the more accurately we fly the better you can do your job and the more effiently ATC can move traffic.
We are the traffic, not data tags. Anyone travelling on the flightdeck can see that we are now using a 100 metre swathe of that 5 mile (assuming it is drawn between VOR's with the required legal distance) or wider airway.
As forget points out, throw RVSM into the mix, as we're facing here in Europe, and you must surely understand our desire to offset. The major crossing points are going to present some very interesting and salutary experiences.
Why not allow a couple of hundred metres of limited offset in that complex airspace to cover the majority of our encounter time? It must already be built into the calculations previously mentioned as a buffer. Let's use part of it.
As controllers in 'first world' complex airspace you have an entirely undue influence on the wide open airspace we spend the majority of our time traversing.
An off hand reference it being understandable in dodgy parts of the world only serves to illuminate our frustration with your senior colleagues. Get them on a flight deck to see just how our navigational accuracy combined with your tight, accurate and efficient controlling gives us a very nasty sensation in our trepidation glands.
And while they're at it let's have them in a sim to at least give them a taste of what high level windshear, CAT and turbulence from passing traffic can do to a 1'000 feet of vertical separation at upper flight levels.
------------------
Regards from the Towers
[email protected]
[This message has been edited by PPRuNe Towers (edited 27 November 2000).]
You don't have to be around these forums to realise the immense respect we have for our colleagues in ATC. However, your post uses all the reasoning that fills so many of us with dread.
To your way of thinking the more accurately we fly the better you can do your job and the more effiently ATC can move traffic.
We are the traffic, not data tags. Anyone travelling on the flightdeck can see that we are now using a 100 metre swathe of that 5 mile (assuming it is drawn between VOR's with the required legal distance) or wider airway.
As forget points out, throw RVSM into the mix, as we're facing here in Europe, and you must surely understand our desire to offset. The major crossing points are going to present some very interesting and salutary experiences.
Why not allow a couple of hundred metres of limited offset in that complex airspace to cover the majority of our encounter time? It must already be built into the calculations previously mentioned as a buffer. Let's use part of it.
As controllers in 'first world' complex airspace you have an entirely undue influence on the wide open airspace we spend the majority of our time traversing.
An off hand reference it being understandable in dodgy parts of the world only serves to illuminate our frustration with your senior colleagues. Get them on a flight deck to see just how our navigational accuracy combined with your tight, accurate and efficient controlling gives us a very nasty sensation in our trepidation glands.
And while they're at it let's have them in a sim to at least give them a taste of what high level windshear, CAT and turbulence from passing traffic can do to a 1'000 feet of vertical separation at upper flight levels.
------------------
Regards from the Towers
[email protected]
[This message has been edited by PPRuNe Towers (edited 27 November 2000).]
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Thanks for your comments PPrune Towers but I must say that I am very surprised by some of them. You are right in saying that us "first world" controllers are fortunate to have good training and equipment.
I have never had a pilot complain I have been under separating them.
Whenever I have offered a RVSM level, I have never had any of them refuse it. This is what surprises me about your statement. If you are not happy with RVSM then tell someone. But I suppose you don't really have much control over it as its the bean counters who really want RVSM.
A couple of hundred metres in an offest is not really a problem. It would be very difficult to detect on a radar screen. But when off radar coverage the same problems as listed above will still apply. I am perfectly happy for you to do it as long as I am allowed to consider you "on track" for calculations.
I have never had a pilot complain I have been under separating them.
Whenever I have offered a RVSM level, I have never had any of them refuse it. This is what surprises me about your statement. If you are not happy with RVSM then tell someone. But I suppose you don't really have much control over it as its the bean counters who really want RVSM.
A couple of hundred metres in an offest is not really a problem. It would be very difficult to detect on a radar screen. But when off radar coverage the same problems as listed above will still apply. I am perfectly happy for you to do it as long as I am allowed to consider you "on track" for calculations.
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Nicely said, Towers. Repeating myself ad nauseum, I am still goggle-eyed at the resistance to this idea from people who should know beter. It should be built in to all FMS equipment to kick in automaticaly above (say) 10,000'.
In an ideal world, we'd always fly on unidirectional airways. (I believe Eurocontrol are working towards that, and all power to their deliberations and may it cme t pass soon.) But it ain't gunna happen tomrrow, particularly outside Europe, so please, someone in authority, introduce 1 mile right offsetting as an interim measure before another incident - or even worse, accident - occurs.
All you journos out there, this is one subject about which you'll quite likely get lots of co-operation from pilots if you chose t make a feature of it.
In an ideal world, we'd always fly on unidirectional airways. (I believe Eurocontrol are working towards that, and all power to their deliberations and may it cme t pass soon.) But it ain't gunna happen tomrrow, particularly outside Europe, so please, someone in authority, introduce 1 mile right offsetting as an interim measure before another incident - or even worse, accident - occurs.
All you journos out there, this is one subject about which you'll quite likely get lots of co-operation from pilots if you chose t make a feature of it.
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Even if it became standard procedure to offset to one side of the track, in this particular incident as the A330 and A340 were both heading in the same direction they could have the same offset programmed and so the result would have been the same. As the overtaking aircraft was visual with the lower aircraft would it not be be a good idea, in this type of situation, to fly slightly right or left of track until past? Obviously may not be as easy under radar control.
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Though I'm not familiar with the Austrailian system it seems intersting that an offset could cause the ATC computer's tracking algorithm to not detect that the aircraft was the one on a nearby planned route of flight. In the terminal environment in the U.S. (and I think enroute too) the secondary radar (beacon) gets a target report, correlates with the primary target and matches them up if they are at the same point in space, tags the data block to it and updates the track file that the display is made from. Uncorellated targets are worked on the next time around and if still unresolved taged as unknown ID speed and alt unknown.
The Automatic Dependent Surveillance bit is very attractive to the beancounters until you tell them that it is only as accurate as the aircraft's knowledge of it's own position and that though it has been made to work in tests it hasn't been used much in the real world, unless you count United transPac to Oz with FANS, which I understand was a big bust.
Combine with that the fact that the data link standards are not set (1090, VDLMode 3, VDL mode 4, etc are possibles) it will be a long time before anything like this can be really operational.
It would be very interesting and instructive to gang a bunch of simulators together with an ATC and try RVSM, ADSB, Free Route and other things in a virtual world. though it would cost millions it would be a lot cheaper and safer than the possible bent metal, let alone wasted money, it there are some unexpected fatal flaws in the concept.
The Automatic Dependent Surveillance bit is very attractive to the beancounters until you tell them that it is only as accurate as the aircraft's knowledge of it's own position and that though it has been made to work in tests it hasn't been used much in the real world, unless you count United transPac to Oz with FANS, which I understand was a big bust.
Combine with that the fact that the data link standards are not set (1090, VDLMode 3, VDL mode 4, etc are possibles) it will be a long time before anything like this can be really operational.
It would be very interesting and instructive to gang a bunch of simulators together with an ATC and try RVSM, ADSB, Free Route and other things in a virtual world. though it would cost millions it would be a lot cheaper and safer than the possible bent metal, let alone wasted money, it there are some unexpected fatal flaws in the concept.