Offsetting - time to make it official just about everywhere

[410]

I see that the in the remarks that follow the daily NAT tracks details now say:

"CREWS ARE REMINDED THAT WITHIN NAT REGION, THE STATEGIC LETERAL OFFSET PROCEDURE, SLOP, SHOULD BE USED AS A STANDARD OPERATING PROCEDURE AND NOT SOLELY FOR TURBULENCE/WEATHER AVOIDANCE". (My boldface.)

Anyone caring to do a search through my posts will see that I've been a lone voice in the wilderness for quite some years now pushing for offsetting for all enroute flying.

So given that the NAT authorities now seem to have seen the light and acknowledged that offsetting does increase safety and should be used at all times in NAT airspace, is it time for us to start calling for it to be used everywhere avove (say) 20,000' - ideally as a built-in feature of our FMCs?

It's not as though we have to wait for an accident that results in major loss of life to occur to prove how incredibly overdue this SIMPLE change in procedures is - it's happened already, and not just once. The recent tragedy in Brazil is just the latest example of a disaster that would have been nothing more than an airprox report - (and maybe, with ignorance being bliss, not even that!) - had both aircraft's FMCs had a built-in 1/2 mile offset whenever they were in LNAV and above 20,000'.

[cribble]

Concur, with the proviso that the technique should not be used on User Preferred Routes or Random Routes ie only use the technique on airways or on designated routes (eg NAT TRK or similar).

[TwoOneFour]

So given that the NAT authorities now seem to have seen the light and acknowledged that offsetting does increase safety and should be used at all times in NAT airspace

From what I understand offset flying has been available as an option on NAT tracks for some time, and the NAT authorities, far from "seeing the light" were actually bitching last August (nearly a year ago) about the lack of take-up from transatlantic crews, only one in 10 of whom were bothering to offset when two alternative tracks - 1nm and 2nm to the right - were open and available. These stats were circulated within NATS and through other outlets.

If the offset option's been available on NAT tracks all that time, surely the question is: Why aren't crews doing it? :confused:

[Basil]

Perhaps they think it's carbon offsetting :):rolleyes:

[BelArgUSA]

I support the concept... however only if in RVSM/MNPS airspace and no need to do 2 or 3 nautical miles... 1 mile is enough... I fly from South America to Europe, and often tempted to change the last digit of longitude to get an offset... to the right...
xxx
We have triple INS (LTN-92) with 2 GPS updating, in our old 747-200s, so it is still time consuming to enter such corrected data without errors...
xxx
:)
Happy contrails

[410]

If the offset option's been available on NAT tracks all that time, surely the question is: Why aren't crews doing it?Because, in from experience, many simply can't be bothered, which is why I believe it should be built in to our nav systems.

For those who want revervations, (as some have already stated in the first few posts), consider the accuracy of the current IRS/GPS systems - for instance, how often do you see opposite direction traffic NOT go exactly over or under you? - and then consider how wide an airway is. Even with an offset built in, the aircraft is going to be well within the confines of the airway.

For those with reservations, my suggestion is that the offset should 'kick in' only in RNAV, and, I'd suggest, only gradually after (say) four or five minutes or maybe even longer in that mode. If the aircraft is being vectored by a controller, it goes onto the heading called for and stays there, and if the aircraft is cleared "direct to" a waypoint after being radar vectored, I can't see a gradual introduction of a 1/2 mile offset after the first few minutes back in RNAV mode is going to make any difference to separation.

Even if it does require some ATC procedures to be modified to provide the separation demanded by the mathemeticians, surely the increase in safey margins would be worth it.

Separation can be lost sometimes, for any number of reasons, as was illustrated all too clearly by the Brazil disaster as well as a number of other earlier collisions.

I simply can't understand how few of us who fly what are quite literally speeding bullets continue to be happy, (some might say apparently blithely unaware), about having a lot of other speeding bullets flying in exactly the same vertical plane as we are when a few lines of computer code (and some legislation) would automatically put those other speeding bullets into a completely different vertical plane.

This one step would decrease the chances of two passenger-laden speeding bullets hitting each other by an enormous degree should human error (be it a pilot's or a controller's) and/or some other problem allow a mistake to me made as it would seem was made in Brazil.

[eyeinthesky]

QUOTE
From what I understand offset flying has been available as an option on NAT tracks for some time, and the NAT authorities, far from "seeing the light" were actually bitching last August (nearly a year ago) about the lack of take-up from transatlantic crews, only one in 10 of whom were bothering to offset when two alternative tracks - 1nm and 2nm to the right - were open and available. These stats were circulated within NATS and through other outlets.
UNQUOTE

Of course, if everybody offsets by the same amount, there's no point in doing it! It just moves the problem a mile or two to the right.

(Offsetting to the right will protect against opposite direction traffic but not same direction)

[TwoOneFour]

Of course, if everybody offsets by the same amount, there's no point in doing it! It just moves the problem a mile or two to the right.



That's missing the point entirely in my opinion - the NAT tracks offer 1nm and 2nm offset which, when you consider the centreline track as well, gives crews three options.

On average, you ought to have a situation where the traffic density is spread across three tracks, reducing the collision risk.

No-one's saying everyone has to offset. What's being offered is the chance to lessen risks by having two-thirds of crews follow something other than the centreline. Instead 90% of crews are still going straight down the middle.

[411A]

Hmmm, seems to me that if a 'built in' offset was on some aircraft with new(er) kit, and not others, one would have the requirement for RNP 0.3 thrown out the window with the bathwater, and the whole idea would be a total and complete waste of time.

First it was....we aren't accurate enough (Navigators), then it was...we need something better that basic INS, and now it's...we are too accurate, so offsets are needed and should be mandatory.

Poppycock, I say...stick with the plot and fly the aeroplane on the airway centerline, instead of adhoc nonsense.

[Shaka Zulu]

Right common sense:

No Rdr over Siberia: Offset 1R or 2R
Aircraft ahead 1000' above your Lvl and closing him down: Offset 1R due turbulence
Africa: Always SLOP, dangerous territory
NATS: Only SLOP when other Aircraft are ahead and above/consider losing an engine and having to turn of the tracks....

[Wiley]

Why am I not surprised to find that our old mate 411A is a 'straight down the airway centreline' (sorry, 411A, centerline) man.

...and TwoOneFour, I think you'll find that 410 is indeed saying that everyone should offset 1/2 NM so that (not in the usually one way NAT airspace, but in the rest of the world), no one will be on the centreline on a two way airway.

[ARINC]

I support the concept... however only if in RVSM/MNPS airspace and no need to do 2 or 3 nautical miles... 1 mile is enough... I fly from South America to Europe, and often tempted to change the last digit of longitude to get an offset... to the right...
xxx
We have triple INS (LTN-92) with 2 GPS updating, in our old 747-200s, so it is still time consuming to enter such corrected data without errors...
xxx
Happy contrails
Hi BelArgUSA your post intrigues me....do you have to manually enter offset waypoints ?? Only have experience of of -400 so not familiar with your FMS fit.

[PPRuNeUser0183]

I disagree that the offset should be integrated, that's going to lead to all kinds of confusion surely (when would the aircraft return to the AWY centre-line? This would be uncommanded presumably - most disconcerting!)

I presume this discussion came about after the article in Flight a month or so ago. It's been published in the track message for ages, and most seem to ignore it. Personally, I see no reason to offset unless there's other traffic around flying at a different speed, and in any case, try to return to the C/L by the exit point.

Curious.... do any of you consider this when it comes to your preference turning off track for an engine failure/drift down? Look out!!

Should there be a standard procedure according to the crosswind component as to which a/c offsets??

[Fubaar]

Most people who've replied seem fixated on the North Atlantic. I understood 410 to be saying it should be introduced everywhere else as well, where most airways are two way and a half mile offset would set opposite direction traffic apart by one mile, (which would have saved the pax and crew of the 737 in Brazil).

Personally, I can't understand the resistance to the idea. I'd much rather see opposite direction traffic fly past me to one side than right over or under me.

What's the problem of being a half mile from overhead the aid when flying overhead IF YOU"RE ABOVE FL200? With 410's suggestion, the offset wouldn't be activated if you were below 20,000', like when you were doing an approach, the only time it would matter a damn if you're absolutely overhead the aid or a half mile to the right of overhead.

[GMS]

411A,

May I sugest you read about the near encounter between a Turkish Airlines Airbus and a canadian Airbus on a NAT track. This might change your views.

GMS

[338C]

Offsetting is particularly advantageous on two way routes as it ensures that aircraft passing head on are at least 1 NM laterally separated.

On NAT tracks it can minimize wake turbulence from overtaking aircraft.

Random tracks across the North Atlantic are similar to two way routes as the same route can be planned for an east or west bound flight and when offsetting is utilized protection as previously mentioned is provided.

There is a safety case to be made that anything a pilot can do to strengthen defenses in the ATC system the less likelihood of lapses and omissions resulting in an incident or accident. Offsetting strengthens the ATC defense system. Operational crews are the direct beneficiaries.

Consider deciding prior to take off that offsetting will be utilized and whether it will be 1 nm or 2.

[BelArgUSA]

I have been absent from NAT tracks since 2004, so I cannot open my mouth about that airspace... I fly the South Atlantic routes South America to Europe with permanently published tracks between North East Brazil (Recife/Natal/Fortaleza) to the Sal/Cape Verde and Dakar FIRs, where permanent tracks are published. Very few random tracks are in use...
xxx
As far as flying Africa, from the Southern Border of Algiers FIR, until reaching the Johannesburg FIR, I had some crossings of entire FIRs with NO ATC conracts whatsoever. ACC controllers in Chad, Central African Republic, or Zaire-Congo were... alseep, or unplugged their VHF or HF radios from the only outlet to warm-up the water for tea or coffee... or watch TV... In these areas, I often had the urge of being 200 feet above or below assigned level...
xxx
For ARINC - the big problem with our prehistoric 747-200s, is that they have no FMS... After initial positioning of the LTN-92 INS units, we XFILL waypoints to waypoints manually to the other 2 units. Works great, accurate and no problem for lateral NAV, update by GPS... In the past, before the GPS update, it was DME update... But VNAV functions are inexistant... So the autopilot will track with accuracy, but climbs or descents require human brains for planning. The 747-400s are an entirely different breed... You are lucky...
xxx
:)
Happy contrails

[410]

338C, perhaps if I'd phrased my first post even halfway as clearly and succiently as you did your contribution to this thread, more people might have been able to understand my suggestion.

I liken our current enroute procedures with ultra accurate GPS and IRS navigation equipment to walking down a rifle range (for eight or twelve hours at a time!) exactly under the firing line of a constantly changing, highly trained(?) team of marksmen firing a bullet over my head every five minutes, and trusting that the constantly changing marksmen will always fire over my head.

In 9999.9% of cases they assuredly will, but once in while one might let his point of aim drop.

...and, (if I must walk on the rifle range), if I took the simple 'belts and braces' precaution of always walking one pace to the right of the very accurate firing line, I'd always be out of the line of fire laterally as well as vertically.

It's not rocket science to see that this has to be a safer procedure than sticking to the centre of the airway.

[FE Hoppy]

I agree that SLOP should be used whenever possible. Of course all offsets should be cancelled when aproaching the first waypoint of a published procedure.

Rather than building in a fixed offset perhaps a random innaccuracy when operating in RNP > 1 airspace?

Just a thought.

[Andu]

If the posts so far on this thread are anything to go by, any such measure would have to be something built in to the system and out of the individual pilot's hands completely, for it would seem that everyone who thinks it's a good idea has his own ideas on how and when it should and shouldn't be done.

And I suspect the vast majority would continue to do nothing unless it was done for them. This says a lot about the trust most of us put in an ATC system that has been proven in a couple of very high profile cases to be overloaded and sometimes flawed.

What's going to be really interesting is if the findings in the Brazil tragedy (or some future midair tragedy) say the accident could have been avoided if a policy of NOT flying on the airway centreline had been introduced worldwide some years ago - as some professional pilots, like "410", have been calling for here on Pprune from the earliest days of the site. (I can remember reading "Lessons from Delhi", [that called for offsetting], on the PPrune Home Page many years ago now, Danny, if available bandwidth allows it, maybe you could consider putting that back on the Home Page where people can read it.)

[ARINC]

For ARINC - the big problem with our prehistoric 747-200s, is that they have no FMS... After initial positioning of the LTN-92 INS units, we XFILL waypoints to waypoints manually to the other 2 units. Works great, accurate and no problem for lateral NAV, update by GPS... In the past, before the GPS update, it was DME update... But VNAV functions are inexistant... So the autopilot will track with accuracy, but climbs or descents require human brains for planning. The 747-400s are an entirely different breed... You are lucky...
Thanks BeLArgUSA must be quite a performance and as you mentioned very easy to make a mistake.
For the record I only remove/refit the boxes, I don't fly by them...:ok:

[Basil]

GMS,
near encounter between a Turkish Airlines Airbus and a canadian Airbus on a NAT track
Don't recollect that one.
Do you know when it happened and which authority carried out the investigation?

With thanks, Bas

p.s. Used 1nm R offset for years - in appropriate circumstances.

[GlueBall]

And what's next. . . ? Offset your altitude? I've flown with one whacko copilot who thought it would be a good idea not only to fly a parallel track, but to offset our assigned flight level by 150 feet. :confused:

[MTOW]

It would seem you are indeed a "voice in the wilderness", 410, and not very many here agree with you that something should be done. As someone has already said, it would seem to suggest that most of us have total trust in the system we all operate in.

I wonder if the Brazilian crew were among that great majority?

[India Four Two]

MTOW, do I detect a slightly ironic tone in your post?

I have followed this discussion and the Brazilian crash thread with interest and have some observations about offsets. Before someone jumps all over me, I should state that I am not a commercial pilot, but I do have IFR/airways experience and I have a lot of experience using GPS not only for navigation, but also for precision surveying in the oil industry.

For all those people who worry about dialling in a 1nm offset, a 0.1 nm offset would take away ALL the risk of a head-on collision, even between two A380s, under worst case GPS accuracy.

Although I imagine seeing an A380 closing at 1000 kts and passing with a wingtip separation of 100 m or so might be unnerving to say the least, but you would miss each other.

[FullWings]

We're getting there but the pace of adoption is very slow. I've been flying offsets for a long while but with the widespread use of GPS I think the potential dangers of not offsetting are getting greater all the time. Gone are the days when you could count on random differences in track-keeping and altimetery to increase separation: we're all flying to within feet of each other now. :eek:

The NATS is probably one of the safer parts of the sky as it is closely monitored by what I would term "competent authorities" but even there, it's a good idea to use the SLOP as a backup, just in case. If I'm not on a direct routing or in a positive radar environment, I reach for the offset function on the FMC; there's even an argument for this when on a "direct" as others may be getting exactly the same coming the other way...

I operated down to Oz for the first time last year and applied an offset - informing ATC as the regs. suggest. They seemed slightly upset by this as if it somehow reflected on their controlling standards - I replied that there was no radar and they were relying on position reports, so I felt fully justified in going a bit to the right and it made me happier, which is what counts. :)

[410]

ATC ... seemed slightly upset by this (offsetting) as if it somehow reflected on their controlling standardsI've had the same reaction from ATC, once in Europe when I asked for an offset after the controller asked me to fly for some time at a non-standard level, (because he had too much *** traffic in his area!!!!!), and in Oz before the current procedures allowing SLOP were in force.

I wish we could get the message across that it's not meant as an insult to the ATCOs' competency or professionalism, but (if I may mix my metaphors rather horribly) just an attempt to put another slice of Swiss cheese in the way to help prevent an unbroken error chain.

As has already been said on this thread, I suspect 99.99% of us would never have even heard of the dreadful accident in Brazil if even one of the two crews involved had used this so simple procedure - a procedure that takes all of three seconds to implement (with the confirmation process included).

We wouldn't have heard about it because it wouldn't have happened. At the very worst it would have been an Air Incident Report - IF one of the crews had noticed the lights of the other aircraft as it flashed by. (Even in VMC, it's more than likely neither crew would have seen the other aircraft because if you're on a collision course, there's no relative movement, and relative movement is by far the easiest cue for the eye to pick up.) In IMC and with no TCAS, they probably wouldn't have even seen the other aircraft.

It's been said before by others, but it's worth saying again. I can't understand the resistance to the idea from (it would seem) the majority of line pilots. Are there so many of us out there with such incredible lack of imagination as to not be able to see that any one of us could one day find himself in the same situation as the Brazilian 737 crew?

- obeying every rule in the book
- flying exactly (there's that word again) to flight plan
- trusting ATC and everyone else out there is doing everything right?
- and someone else, over whom you have absolutely no control, makes one solitary mistake.

All it took in the case of the Brazilian 737 was for two holes in Professor Reason's Swiss cheese model to line up.

[Basil]

They seemed slightly upset by this as if it somehow reflected on their controlling standards
Don't ask, don't tell. (Military term - don't ask for the origin ;) )
If you are under procedural control there should be no traffic within miles and if under radar then the radar controlled traffic should not be vectored into you.

[bubbers44]

To avoid nav errors it seems that the only way to avoid input errors for offset would be to have the software automatically put in an offset unless you override it to reduce workload. Missplacing a decimal point could cause a big problem. We don't need to increase workload to use offset, just make it automatic.

[Wiley]

Are there so many of us out there with such incredible lack of imagination as to not be able to see that any one of us could one day find himself in the same situation as the Brazilian 737 crew?It would seem the answer to that is a resounding 'yes'.

I'm an unapologetic offsetter and have been for years. However, from what my FOs tell me, I'm one of the very few captains in the company who does use the procedure, even though it's authorised for particular areas in our SOPs. I've even had one FO take the offset out while I was out of the cockpit on a toilet break because he believed we should be 'on centreline'. (And for 411A's benefit, I suppose I should add that that particular FO is unlikely to do so again, at least with me.)

[Semaphore Sam]

Besides the Brazilian tragedy, can people think of others that might have been avoided with the offset technique? Possibly BA's climbout into an aircraft over Eastern Europe (Yugoslavia?) in the early '90's, or the Saudia/Russian Delhi accident? This idea seems inherently sound, especially in 126.9 territory. Sam

[Andu]

A few that come immediately to mind, (I think there are others).

A couple of corporate and commuter aircraft accidents in the US, one, I think, in the Grand Canyon area, all resulting in death to all on board.

The USAF C141 and the Luftwaffe Tu154 off the west coast of Africa. All killed.

The Saudia 747 head on with the Il76 just west of Delhi. 400+ killed. (Probably not a good example, as neither aircraft was equipped with IRS or GPS, but it was the accident that started the campaign for offsetting here on Pprune way back when.)

I know of three very near misses head on with opposite direction traffic in my own company, all due to altutude busts, (one out of Dhaka, one near Muscat and the third between Hong Kong and Bangkok) that would have been a lot less exciting for all concerned if the opposing aircraft had not been absolutely aligned. In all three cases, the miss was very near indeed.

[forget]

......... near encounter between a Turkish Airlines Airbus and a canadian Airbus on a NAT track. ------ Don't recollect that one. Do you know when it happened and which authority carried out the investigation?

The A330 commander's report. Both aircraft were in clear air as the A330 was slowly overtaking the A340 below it. The A330 commander stated that his aircraft was slightly to the right of the A340 and almost abeam it when he saw the A340's wings start to flex. At about that time he felt a bump, which he described as similar to entering a mountain wave. Five to ten seconds later there was another bump during which the A330's altimeter reading descreased by 200 feet. Immediately thereafter, the A330
commander heard a TCAS "climb climb" warning and he noted that the A340 TCAS symbol had changed colour to red on his navigation display. He looked out and down at the A340 which was some 200 to 300 feet to his left in a nose-up attitude and climbing steeply. The A340 passed through the A330's level before the commander had time to react to the TCAS warning and the
TCAS was still issuing a "climb" instruction for a short while after the A340 had climbed above the A330. The commander continued to monitor the A340 visually and on TCAS. It appeared to reach an apogee above FL380 although by this time it had fallen behind the A330. Nevertheless, it was still laterally quite close to the A330's track so the commander altered course to the right to make space for the A340 to descend back to FL 360.

UKAAIB Report here -

http://www.aaib.dft.gov.uk/cms_resources/dft_avsafety_pdf_501275.pdf

[3rd_ear]

That's really quite an interesting report, not least the CAA recommendations. Of course, if both aircraft had previously offset by the same distance, the situation would have been unimproved. Would it not make more sense to take action much like on the road, and for the overtaking aircraft to change offset in relation to the one ahead prior to overtaking? IANAP, but surely this could also be done safely without visibility?

[fox niner]

If we all offset with the same amount, nothing will change.

In my B777 FMS I can only enter 1NM, 2NM, 3NM etc offset distances.

I would like to be able to enter 0.1, 0.2, 0.3 NM etc but I can't.

[Wiley]

What about opposite direction traffic, fox_niner - which was the main point 410 was covering in his original post?

[fox niner]

Ah, wiley, sorry about that:

Let me rephrase....

In Brazil and Africa I always use 1 NM right of track. Perfect.

However, last weekend I was on track X-ray (NAT) like everyone else and literally EVERY flightlevel was occupied, within a distance of 10 miles. If I were able to enter say 0.5 NM right/left, and the others used some other convenient 0.1 step-distance, everything would work out better on a busy NAT. But unfortunately we have to wait till a software update Blockpoint such-and-such for an improvement.

[Green Guard]

I think you'll find that 410 is indeed saying that everyone should offset 1/2 NM so that (not in the usually one way NAT airspace, but in the rest of the world), no one will be on the centreline on a two way airway.
And what the 'ell is wrong with that ?
Are you also worried that nobody drives OVER the center line, between two opposite lanes of your road?

[MTOW]

That was a bit too cryptic for me, Green Guard. Are you saying you don't think it's a good idea?

[Engineer]

You have read the script so why not look at the film (http://www.scottipc.com/course/content/view/37/61/) :8

The idea is to introduce randomisation that was built in with poorer quality INS system of bygone days. With today's accurate GPS systems you could find your self flying straight down the middle of the NAT track every time.

Since the North Atlantic is a busy place it seems sensible to introduce a little randomisation by electing to fly 1nm offset one day, down the middle the next and then may be 2nm offset the day after. If every one approaches it this way then may be it will reduce the possibility of an incident :D

[Wiley]

... and as the man says in the movie, they can't convince 99% of pilots to do it. The movie points out very well how the increased navigation systems' accuracy has increased the danger should someone, just one person, make a mistake, but the vast majority of us seem to choose to ignore this undisputed fact.

[Danny]

Obviously, asking flight crews to "randomly" insert 1nm or 2 nm offsets isn't working so why not have a mandatory system whereby depending on the flight level being flown determines the offset. There are 3 choices of 0, 1 and 2nm offsets available so it is entirely feasible to introduce a mandatory offset that also guarantees that any 2 a/c on the same track or offset are separated by at least 3,000ft vertically.

FL410 = 0 R
FL400 = 2 R
FL390 = 1 R
FL380 = 0 R
FL370 = 2 R
FL360 = 1 R
FL350 = 0 R
FL340 = 2 R
FL330 = 1 R
FL320 = 0 R
FL310 = 2 R
FL300 = 1 R
FL290 = 0 R

Nah, it can't be that easy. Maybe the ICAO committee need to justify their jobs by somehow overcomplicating it before mandating such simple rules that would increase safety by such a large factor.

Of course, under the current "random" rules, they still have all the a/c converging on the same exit waypoint! :rolleyes: If they were to introduce mandatory right-of-track offsets for all a/c equipped to do so, based on the above criteria for all flying, including airways then there wouldn't even need to be all that converging on a single waypoint at the very edge of radar coverage. Also, we wouldn't have to acknowledge every single a/c that is going to pass 1,000' above or below us in the opposite direction as some eastern seaboard US controllers feel the need to point out to us.

[410]

Danny, you're creation probably has more clout than even you realise. Maybe you could make an issue of this, perhaps get a few of your journo contacts involved. We all love to knock journos the way they sensationalise all things Aviation, but in this case, sensationalism might be what's needed.

I can just see tabloid headlines along the lines of "ICAO refuses to implement safety measures demanded by airline pilots group".

It's not as though the midair in Brazil is the first instance where this ultra accuracy has been the "final hole in the cheese" ensuring an accident occurs. I keep asking myself how many have to die before someone does something.

[Willit Run]

The 747 classic has a fairly decent PMS system that was available. Several of our aircraft have the PMS, it's used to save fuel and reduce pilot workload. It has a glitch in the system though. If the radio altimeter sensed 1500', the auto pilot will disengage from command to manuel. Do you see where this is going? Thats right, a longtime operator of 747 freighters were cruizing along one day/night and another aircraft passed right below them at 1000', triggered the auto pillot to manual. Well, the crew were obviously doing something else and did not notice the tilting point in the airway, and they just cruized merrily along their straight path in manual auto pilot. There is no warning if the auto pilot trips to "manual", only to "off". Hence, an " Airworthiness Directive" was published, that the only time the PMS can be used is in climb or decent or non RVSM environments. Had there been a mandatory offset, this little incident wouldn't have happened, and I would be able to sleep better on the PMS aircraft while making the old man lots of money on saved fuel.

I know this was a long story, but I think the Danny method would be a good thing to adopt.

[Engineer]

Obviously, asking flight crews to "randomly" insert 1nm or 2 nm offsets isn't working

Ask the question why?

Because this is a new operating system (if you consider 3 years new).

Yet if you ask any one what to do in the event of a technical failure which renders the aircraft incapable of maintaining the OTS the reply would be automatic (hope so :)).

Because it has been drummed into you via the training department/operations manual.

So there is no need to set up any system to ensure compliance just annotate it in the operations manual (example shown below) and ensure every one is trained correctly.

My view the answer to the above question is Airmanship

Strategic Lateral Offset Procedure (SLOP)

With widespread use of GPS, lateral navigation accuracy has increased significantly. There has been a corresponding increase in the probability of critical traffic conflicts resulting from height deviations (altitude deviation errors, turbulence, etc...).

As a result, pilots should use the Strategic Lateral Offset Procedure as standard operating practice in the course of normal oceanic operations to mitigate collision risk and wake turbulence by distributing aeroplanes laterally and equally across the three available positions.

SLOP will be applied using the following guidelines :

a) Aeroplanes without automatic offset programming capability must fly the centreline.

b) Aeroplanes capable of being programmed with automatic offsets may fly the centreline or offset 1 or 2 NM right of centreline to obtain lateral spacing from nearby aeroplanes.

c) Pilots should use whatever means are available (e.g. TCAS, communications, visual acquisition…) to determine the best flight path to fly, and to benefit in randomly distributing traffic across the three available positions.

d) Any aeroplane overtaking another aeroplane is to offset within the confines of this procedure, if capable, so as to create the least amount of wake turbulence for the aeroplane being overtaken.

e) For wake turbulence purposes, pilots are also to fly one of the three positions at b) above and never offset to the left of centreline nor offset more than 2 NM right of centreline.

Note : It is recognized that the pilot will use his/her judgement to determine the action most appropriate to any given situation and has the final authority and responsibility for the safe operation of the aeroplane. The inter-pilot frequency, 123.450 MHz, may be used to co-ordinate the best wake turbulence offset option.

f) Pilots may apply an offset outbound at the oceanic entry point but
must return to centreline at the oceanic exit point.

g) Aeroplanes transiting radar-controlled airspace (ex : Bermuda, Guam, Vancouver centre...) are to remain on their established offset positions but must advise the radar controller on initial contact of their offset status.

h) There is no ATC clearance required for this procedure and it is not necessary that ATC be advised.

i) Voice position reports are to be based on the current ATC clearance and not the exact co-ordinates of the offset position.

It is simple it just needs a change of attitude and approach to flying in congested airspace. The only other place that this procedures is used is India (umbrella up :hmm:)and this is a result of the booming airline industry that is apparent today.

[PPRuNe Towers]

It couldn't happen to me?

http://www.pprune.org/forums/showthread.php?t=287414

Rob

[1xxxxx1]

Interesting discussion and an eye opener that I’m following since some weeks.

Flying a bizjet puts me out of range most of the time when operating above FL410 but I started watching opposite traffic and the result most aircraft are right on centerline and thanks to RVSM at the right altitude. :=
Before I had the impression that all airline drivers are flying offset to the right when in non radar environment like over Africa or Indian Ocean etc.
I’m not talking about the NAT track system as this is one way traffic or flights under radar control what might make some problems to ATC. (actually I was already corrected by China ATC for offset flying)

But since I have an FMS or GPS function allowing to fly parallel track I use it.
Offset 1NM to the right on all enroute airways surely when out of radar controlled airspace.

This is good airmanship and would have avoided some accidents as stated before.
And 1NM to the right cost nothing more, makes no problems and is no work besides typing “R” “1” “enter” in most boxes.
Let’s be honest; what else you have to do in this phase of flight than drinking coffee and with much less possibility of an RA you might not have to spill it. :ok:

[PPRuNe Towers]

Reference my post back in August and the turbulence induced loss of separation.

I'm looking now at the paperwork triggered by another separation and height bust - 1500ft in this case and I've personally spoken to the crew involved - they could not stop it happening.

The facility, paperwork and permission is there for you to use. SLOP is described above and really should be considered a vital bit of self defence.

Rob

[Shanwick Shanwick]

Am I the only one doing this on a regular basis? I always offset to the maximum of 2 miles as no one else seems to bother. Always get strange looks from the FO's when I suggest it.

[Feather #3]

Apart from a UK professional body putting forward a random "fly-right" offset as part of the FMC program, offsetting is all the go down South after our company had two near-hits which this procedure would ameliorate.

Chinese ATC on B215 now TELL you to offset 1nm right [and this would fix the NAT issue too!]

However, pilot discretion may not always work. One of our a/c on the oceanic bit of Myanmar's airspace, flying 2nm right, had another carrier's a/c go precisely underneath them. They called the guy to ask why he was 2nm LEFT?

The answer was that everybody else flew 2nm right and he was going to be different to increase his collision risk margin!!:confused: Bit hard when confronted by that logic!!??:rolleyes:

G'day ;)

[overstress]

Am I the only person to wonder why the OTS is referred to as NAT Tracks?

i.e. North Atlantic Track Tracks

rather like SAM missiles

or PIN Numbers

ATM machines
PAC code
LCD displays

etc

overstress (1 mile R of track)

[misd-agin]

Centerline, R1, R2. It varies depending upon overtaking traffic.

I like the one mile seperation view, especially if I"m on the sun side.

The majority of guys don't offset so they pass on the sunny side and ruin our view. How about some consideration? :ooh:

[Wiley]

At the risk of stripping my Pprune anonymity, and judging by comments from my FOs, I think I'm one of the very, very few captains in my airline who regularly flys offset.

I think - (if only after quite a few hundred more people die proving the point) - future generations of airline pilots are going to look back at 'old timers' like us and say in tones of utter incredulity: "You mean for years and years after IRS and GPS came into everyday use, you continued to fly on centreline? And some regulatory authorities actually forbade offsetting?"

And if it does ever change, (with the Chinese apparently leading the way - well done, China), I think we can all thank Danny and this site for playing a major role in pressing for its implementation.

[4Greens]

Outside radar cover, just do it.

[410]

Interesting the way Chinese ATC has adopted offsetting within radar coverage (I'm assuming) as a 'belts and braces' measure with their switch to metric RVSM. I've been told on two occasions now to offset two miles right by Chinese ATC and on another, to cancel the offset just prior to top of descent after I had left in after leaving Yangoon airspace.

I find myself asking if they haven't got the right idea and whether other ATC agencies shouldn't follow their lead. Let's face it; it's an unassailable FACT that if Brazilian ATC had done as Chinese ATC so often does, there'd be a hundred or more fewer grieving families in Brazil today. As I've said more than once here, I simply can't understand the set-in-concrete resistance so many people in the industry have to the idea - and let's bring on with minimal delay a built-in offset to all FMCs in RNAV mode when above 20,0000'.

[javelin]

Simple solution - when Shanwick or Gander give you your clearance, they state the offset. They are planning the Ocean, they know where you are, you can have just as big a problem with 2 following guys offsetting the same amount as flying the centreline.

[410]

True for the North Atlantic, Javelin, but there is an awful lot of sky out there that isn't on the NATS tracks. That's the sky most of us are talking about.

[javelin]

I think most operators over remote areas such as Africa/South America have been offsetting for years - the recent work has been on the NAT system. Our company have been trying to get us to do it either on a random basis or as advised by Flight Planning. This just doesn't make sense when the two authorities could allocate offsets so easily.

The future must be micro offsets when the boxes can sort out decimals of offset.

Then you get the gem of a report about one of our Seniors who insisted offsetting left :D :ugh:

[rab-k]

Javelin

The only downside to your suggestion is that, as things stand, it is the 'random' aspect of the uptake which keeps the statisticians happiest.

However, the problem came about when some clever-cloggs deduced that the uptake of SLOP was less than 10% - hence the note on the track signal to try to encourage crews to adopt the procedure as a standard, not just for overtaking or wake vortex situations. Random is good, but not when +90% don't play ball.

A few more crews are taking up the procedure and we can 'see' those who are ADS equipped and who do set up an offset in Oceanic, as the ADS position report comes down to give the game away, so to speak.

The problem in us telling you whether to stay on track or offset 1 or 2 nm would not only affect the randomness of the whole thing, but we can't tell from the ground what capability the aircraft has and whether or not it would be feesable to instruct a flight to offset. (I know some FMCs allow for easier offsetting than others and a few don't cater for it at all).

We have discussed amongst ourselves a system whereby if you're at an odd FL you offset 1nm, evens 2nm, if unable remain on track, but as mere mortals we can only fire such suggestions up the chain, and who knows where they end up.

[javelin]

ADS, It's the future, bit like garlic bread !

Our big aeroplanes are about to get upgraded to.........................VHF ACARS :ugh:

Great for clearances and weather but still not CPDLC although some are so equipped. Another course, another toy to play with.

How long before all traffic above FL XX needs to be ADS equipped for NAT crossings ?

In the meantime, I will continue to speak to the very nice folks at Ballygirreen :ok:

[411A]

In some circumstances, SLOP is a complete and utter waste of time and effort.
Why?
Flying eastbound across Africa not all that long ago, EgyptAir was heard to be told by Khartoum to descend from FL330 to 290 due to crossing traffic.
The EgyptAir flight, clearly not liking this reasonable idea, simply went silent...no further contact was heard on the frequency.

SLOP....phooey:}

Fergetaboutit.

[rab-k]

I've heard that over certain parts of the 'dark continent' a 500' departure from a cleared level is also used by some crews, along with an offset >2nm.

Slightly off topic, but ADS may become a requirement for reduced longitudinal separation, particularly when climbing/descending through the level of other similarly equipped aircraft, with less then the current longitudinal minimum.

Watch this space...

[Fg Off Kite]

Perhaps offsetting will evolve over time through natural selection where all the centerliners will eventually be killed off!

It reminds me of when in the 90's following a spate of collisions of fast jets at low level in the UK, it was suggested to the flight safety empire that they could halve the risk of collision by alternating odd and even squadron numbers flying at 500' and 250'.

Nothing happened of course, such a colmplex system would perhaps be far too difficult to administer, and the training value lost would not be justified by saving the odd aircraft!

Rather than persuading the cash critical airline industry to spend money on electric kit and software to enable offsetting, why not draw a couple of extra points on the map at each TP and just join a different set of dots?

[Wiley]

Rather than persuading the cash critical airline industry to spend money on electric kit and software to enable offsetting, why not draw a couple of extra points on the map at each TP and just join a different set of dots?Even disregarding what the charts would look like (yikes!!), think for one moment what that would do to the size of navigation data bases, to say nothing of the problem of finding almost double the number of pronouncable five letter waypoint names.

I think some sort of built-in offset is inevitable, and suspect that it is being resisted for very much the same reasons proper security measures were resisted in the US, until they got the proverbial wet fish smacked across their faces six years ago - $$$$$. When the $$$ cost of not implementing it equals the $$$$ cost of continuing to use our current 'on centreline' procedures, things will change.

My guess is that it will be the civil suits served by some bottom-feeding lawyers representing the surviving relatives of some passengers killed in an incident similar to the head on collision in Brazil last year that will swing it, when they argue that the airline/FMS manufacturers/regulatory authorities/toilet cleaners at Boeing or Airbus did not provide a safety measure that it was known - and widely discussed (as in here on Pprune) - would increase safety margins.

I'm surprised it hasn't happened already over the Brazilian collision, and in this case, 'bottom-feeding lawyers' might actually achieve something for the good.

[flash8]

actually I have also been pushing offsetting for many years.. even posted on pprune about it.... makes incredible sense... glad this topic has raised its head again

[410]

This was one of the early 'serious' issues covered by Pprune way back in its infancy. It would seem the archives have moved, for the links to the two original articles that Danny once had on the PPrune opening page (now gone), don't work any more.

Mods, newer readers to the site might like to see http://www.pprune.org/forums/showthr...=Lessons+Delhi
and http://www.pprune.org/forums/showthr...=Lessons+Delhi
if they're still accessible with some other link.

There are also a few other threads on the issue:

http://www.pprune.org/forums/showthread.php?t=15713&highlight=Lessons+Delhi
http://www.pprune.org/forums/showthread.php?t=260454&highlight=Lessons+Delhi

and there was quite a bit of discussion about offsetting in the thread about the midair in Brazil last year.