Radar problem North Sea sector?

[Cavemonster]

Anyone out there understand what's going on? Allegedly there is a new instruction that controllers must apply 5nm lateral separation between tracks flying the same route even if they are vertically separated!!

Is this something to do with the radar that broke in the storms recently or is it a new problem?

If there's a technical bug with the Swanwick kit, shouldn't this have been exposed during testing before the system is declared safe to use?

:confused:

[atccmm]

It seems the problem with the radar is actually the Mode C readout. There are some anomalies in some of the north sea area where the Mode C is shown incorrectly. This problem, they say, will be sorted in a couple of years when Mode S is introduced, but until then, 5 miles separation needs to be used, regardless of the vertical profile.

I agree that maybe this should have been spotted before Swanwick opened.

The question I want to ask is this. If there is no fix, then does that mean this problem existed at West Drayton before we moved to Swanwick? If so, why the hell wasn't it detected sooner!

[Madrigal]

:confused: Does this sound correct to anybody else?

I can't believe what I see on the radar anymore - especially if the blips merge. Hence the additional separation. However, if I switch the radar off and control procedurally, I can trust the pilots level report and leave them on their own navigation! Which may be easier than vectoring near a very active danger area.

Progress?:mad:

[Minesapint]

Sound like we need Main Mode back. Is it a problem with the SSR head at Claxby? If so, get the thing changed.

I understand that the 'Radar Upgrade Programme' has ground to a halt? I think that Mode S is going into TC in 2005. No other info.

:rolleyes:

Except that the one area where 'management' must not cut corners is the NATS radar system. Taking 5 on vertically separated traffic is ridiculous!

[Ahh-40612]

The Titanic keeps on charging at the iceberg!

If EVERYTHING needs to be on a heading to miss everything else by 5+ miles, then surely that will at least double the WORKLOAD.

Immediate halving of TSF's seems the appropriate remedy.

[ZIP250]

I think this is caused by a processing problem with the Swanwick system. The instruction (apparently from SRG) is that all aircraft within the affected area must receive four (not five) miles lateral separation when already vertically separated!!! What happens if this is not applied is that the STCA and SMF bits are triggerred and although separation was never lost it means more paperwork for the investigators. Now there is an instruction to do this ridiculous procedure the humble ATCO can be blamed for the system failure when these alerts are triggered.

It would seem that some watches have reduced the combined sector 11/33 TSF by about 15%. Do people think that this is enough or should it be even more restrictive?

Thoughts please.

Z

[Direct HALIFAX]

TSF reduced from 38/60 to 33/60. Thats a reduction of 13%. Is this problem isolated to North Sea sectors.

[Cavemonster]

Goodness Gracious! This sounds a bit tasty.

Like the previous postee I'm wondering why the problem would be North Sea specific. As NERC uses MultiRadarTracking I would have thought the problem could manifest itself anywhere.

Anyhow, it sounds like the management have done the right thing in reducing the TSFs for the affected sector in concert with the issuance of the instruction. From a customer service angle this is quite a brave step given the huge delays North Sea sector tends to generate! Maybe this is a sign that the old ways are on the way out and the new incumbents are on the same side as the workforce. Or did SRG insist on the TSF reduction?

[ZIP250]

Management did NOT reduce the TSF nor did (to the best of my knowledge) SRG say anything about TSF reduction. The SI was issued for the new procedure and it was left entirely to the operational staff to decide how to implement it. I am told that on Monday (the weekend was off route so the impact was less) the Sector teams in conjunction with the LAS decided unilaterally to reduce the TSF without any consultation with management but with the complete backing of the Watch Supervisor.

ZZZ

[NERC Dweller]

This isn't a Swanwick fault but a fault with the Radar. This has been proven by looking at the raw radar data before Swaniwck even touches it.

From what I understand is that a particular Radar is sometimes having problems decoding the transponder signals from aircraft flying a particular route in the North Sea Sectors.

Why does Swanwick use the bad FL?
The radars should filter out FL which show excessive rates of change - 500 ft in 6 seconds is probably considered excessive. The Mode C would still be passed to Swanwick but with the invalid Mode C bit set. This isn't happening so Swanwick thinks the Mode C is good and uses it.

Why not just use Single Radar Mode in this area?
You would still get STCA alerts as the ALP processors use Multi-Radar tracking, as its better for lateral tracking.

Why was this not spotted during Swanwick testing?
1) Its a Mk 1 eyeball test using real live radar feeds, easy to miss especially if it only happens every now and again.
2) Most of Swanwicks tests were done with manufactured radar data which doesn't have this problem

[mainecoon]

dwell

so why don't all the other units using whatever radar you talk about not have the same problem?:confused:

[055166k]

Dodgy mode C not confined to North Sea, also LND and STU. Gives you a real cold fear feeling of utter helplessness. Here is only one of about five that I've had// Southbound B752 at FL370 just passed LND with a Northbound L101 at FL360 just at the French boundary, both on route// at about 15 miles the L101 shows FL375 for two sweeps , just about to do something bl**dy quick when it returns to normal. I'm beginning to rely on TCAS more than the planes; not only that but when I get a real proximity warning my initial reaction is "SPURIOUS???" On the positive side it has been several weeks since I've had those funny ghost aircraft that fly parallel to the real ones. Not much point in filing///they never get off the unit , so instead we just have a running total on a bit of paper for TELS benefit.

[Hippy]

This explains everything...almost.

Okay, this is what we have so far (from a Lon Mil perspective):

1. Claxby radar is dodgey. We had a memo that basically said, 'Claxby gets dodgey in excessive wind speeds, expect it to be switched off at no notice' - Obviously a problem with the head & not with the processing software.)

2. The sectors formally known as 'North Sea' (SFKANS) have been advised to reduce capacity, either at LAS level or otherwise.

3. From my experience, on random days (maybe co-incident with watch changes at Swanick), sector capacity on SFKANS has been reduced to the extent that a certain operator (operating predominantly, in the early morning, UK to EHAM) has taken the commercially sensible decision of operating 'off-route' in order that their customers may meet their connection at Ship-hole.

4. Said operator places phone call in advance to Lon Mil, with explanation of problem and a request of provision of RAS, (Operator is aware of ludicrously inadequate flight plan processing system at Mil unit), for each individual flight.

5. Mil unit explains that they would be more than happy to offer service, but unlike a similar service provided by a civil unit in the North, provision of service will be subject to traffic load, with a clearly defined priority list, (and a clearly demonstrated incident investigation procedure!) and as such, can not be guaranteed in advance...

6. ...However, provision of service is very rarely refused and a RAS is applied, with the same separation criteria as, and sometimes against traffic being worked by, the SFKANS - and get this bit - using the same Claxby Radar!

So, my points are:
If it is true, why is SFKANS being made to work to stoopid criteria that may possibly be circumvented by provision of a Procedural Service?
If the Claxby Radar is so unreliable, why hasn't it been serviced?
If the Claxby Radar is so unreliable, why are 'the mil' still using it to provide min sep for RAS & RC in MRSA/CAS?
Why does a major ATC provider like Lon Mil not have a robust (cool buzzword) FPRS in place?
Why can a £65M ATCC (proclaimed to be the most modern in Europe/The World) not work out it's own MSFL?

Rgds,
Hippy

Okay, the last question is a bit off track, but WHY?

[eyeinthesky]

This is yet another 'quick-fix' SI produced by our Ops dept to cover known deficiencies. What is the point in having vertical separation if you can't rely on it? The simple way out of this is either:

1) Log it as a known fault. If you get an SMF or STCA or 'spurious Mode C' readout, confirm the level of the aircraft concerned and there will be no incident. No further action required.

2) Turn the radar off and use procedural separation of 1000ft and we will be none the wiser.

It's just STUPID to be taking this approach, with the only promise of improvement 'in a few years time when Mode S arrives'.

How, in a 10-mile wide airway, do you keep one at FL320 and one at FL300 4 miles laterally separated whilst still having room to climb the Amsterdam departure five miles abeam to FL 360 and always remaining 2 miles inside the airway or within 5 nm of the UAR centreline or the Mil get upset??

Yet another NATS papering over the cracks:mad: :mad: :eek:

[Cavemonster]

NERC Dweller or anyone

Sorry to be thick but if the radar itself is the problem, why don't I recall ever hearing any spurious mode C complaints when we were at Drayton? Main Mode used Claxby didn't it?

[250 kts]

The thing that really p****s me off is that our Ops people never thought it necessary to flow the traffic as part of the TOI,but also didn't put any requirements on the likes af Maastricht and Amsterdam to stream the traffic into the sector.

I know they were coming in bunches the other day and I heard that in excess of 100 extra headings were used in the course of a single,fairly quiet duty.

The whole procedure is not acceptable as it is and indeed barely workable.:mad: :mad: :mad:

[Direct HALIFAX]

Is the reduction in TSF instigated by the LASs enough? Shold it be further reduced from 33 per hour ??

Any North Sea Ts care to comment ??

[A I]

Now let me see if I've got this right.

1. There was a known SSR Mode C problem on the Claxby (and other) radars whereby the height returns could be unreliable when two aircraft are vertically separated but not laterally.

2. This did not pose a problem on the displays at West Drayton which did not show the spurious readings nor were the various safety devices triggered.

3. This causes a problem at Swanwick because the alerts for the separation monitoring function (commonly known as SMURF) and the STCA are triggered giving everybody unnecessary grief and lots of paperwork even though separation has never been compromised.

4. The excuse is that it wasn't spotted during testing even though it was a known deficiency and it seems reasonable to assume that somebody who knew about the radar system deficiency ought to have been looking for it.

5. The proposed solution is to apply unnecessary lateral separation to prevent the spurious alerts.

6. Swanwick Ops and management did not see fit to recommend a reduction in traffic prior to implementation of this procedure.

7. This came to light at the end of the summer traffic period.

In the words of one Victor Meldrew - " I don't believe it". My mischievous mind has to ask whether or not Swanwick would have been declared fit for purpose if those charged with saying so had known about the problem. Finally I have to ask what other gremlins might be lurking and who knows about them. Was the push to "O" date so irresistable that there is more than dust under the carpet?

[Scott Voigt]

Interesting...

We get what we call mode C swap quite often when you have two aircraft close by. We also have some areas where at times the aircraft are showing an altitude other than what they are really at... When the computer snitch goes off, the front desk just asks what sort of separation we are using and we advise them that pilot reported level, bad mode C and just keep pressing on...

regards

[250 kts]

Thanks for that Scott. hope our Head Of ATC OPS is reading this as an eminently sensible solution to this problem is 2 inches above these words.

[A I]

250kts

I agree that it would be good if ATC ops were to read Scott's sensible reply. Unfortunately the poor chap(ess) was following orders from those nice boys and girls down at Gatwick (ATSSD)

[NERC Dweller]

LACC Multi-Radar Processing.

ATC radars aren't the most accurate of beasts. LACC uses all of the contributing radars to enhance the accuracy of an individual track. I believe the last Mode C to be reported is the one that is used. We should be able to trust this data as the aircraft 'told' the radar. Unfortunately we can't always

West Drayton

Main-Mode only ever used one radar at a time. What it did do was allowed you to set which radar reported for which area (down to 16 mile boxes I've been tolds). So the problem may never have been seen as Claxby may not have been selected for the problem area.

055166k - Both your problems are probably being caused by Mount Gabriel. The ghosting should have disappeared as MRP has been told Mount Gabriel is an 'unreliable' source so should only be used when no other radar is tracking the given aircraft. Unfortunately MRP still uses it Mode C (See comment above)

A I in response to your post

1) Problem only reported after we entered operational service.

2) Can't say never work at West Drayton.

3) Paperwork - I'll leave that to you

4) Couldn't answer that one.

5) The TOI is to increase seperation. The final solution will probably change the Swanwick system, once someone decides what they want to do (ATC, Safety, Engineering etc)

6) I don't work for ATC so can't answer

7) First reported mid-July

In response to your comment

My mischievous mind has to ask whether or not Swanwick would have been declared fit for purpose if those charged with saying so had known about the problem. Finally I have to ask what other gremlins might be lurking and who knows about them. Was the push to "O" date so irresistable that there is more than dust under the carpet?

How dare you call into question the professionalism of the people that slogged their guts out to get LACC operational! :mad: :mad:

[A I]

NERC Dweller,

Thanks for your response. Sorry I upset you and on reflection, I could have worded the last paragraph better. What I was trying to say is that the ATC experts (obviously not you, as you admit) could have been led to believe that certain system features were acceptable and hence their modification was deferred until after "O" date. We really need to know what these might have been.

I believe the Claxby radar would always have been the firstchoice radar for the block in question under the West Drayton system. I don't really see your point regarding reducing separation. This procedure increases the ATC team load because of system deficiency. The SI says that the problem will be solved when Mode S is introduced. We don't have any timescale for this in Swanwick (or none I know about). An engineering solution would be ideal but you are the first on this thread to suggest that it is possible. Is it?

[Minesapint]

Main mode.

16x16 boxes with preferred/supplementary and so on set for each box. Registration and collimation analysis took care of ensuring that the track was seen in the same location - to a parameter limit - by at least TWO radars. Thats the limit of my knowledge...

Except! Each box was split into smaller boxes and different size search area's used in track processing.

[Cuddles]

As a user of the Claxby Radar who doesn't sit in NERC (Or anywhere in the London FIR come to that!!) does this mode C readout thing apply to me? I generally only work sfc - fl 65, but frequently have things at 1000ft and less than 5 miles, I also work SSR only in some areas. So, should I just keep quiet about it, and hope unit management don't cotton on?

What about other units which get a feed from the Claxby = Humberside etc, would they be affected, and if so, why haven't they been told?

Cheers

[NERC Dweller]

A I - No problems. Nice to see you spotted my deliberate mistake;) Of course the TOI is to increase lateral seperation.

I'm afraid I'm at or even beyond my level of understanding in this area so can offer no more info

[Hippy]

Cuddles,

You echo my sentiments entirely. I thought you were NJ till I read your last sentence.

Anyway, Here's the echo:
What about the rest of us who use the Claxby? Are we affected?

[mainecoon]

hippy and cuddles

would also like to echo your question
i have the clxby+gdf in use when i'm forced to work penal (or some range of hills) radar
haven't noticed anything strange but then again stca and smf go off out there all the time

interested to know where the affected area's are

regrds:D

[ZIP250]

Well then there you go! A few rants on PPRUNE and the SI is withdrawn! All back to normal then with an OPNOT advising tacticals that they might like to use a little lateral separation to avoid the problem.

Z:) :cool: :rolleyes:

[Numpo-Nigit]

That's alright then !!!

However, much as I admire the power of PPRuNe, I suspect it was the impact of the reduced flow rates on service delivery that forced the change of heart - see, the LAS does have a useful function!!!

;)

[eyeinthesky]

Whilst PPRUNE is powerful, I think it might have more to do with Alan B getting knobbled every time he entered the Ops Room by NOR controllers dragging him over to the radar and asking him how we were supposed to keep the 5 Eastbound tracks converging on Kippa 4 miles apart from each other.

Apparently the ADNC people got all shirty as well when someone went 1 mile off route trying to keep vertically separated aircraft in the UIR 4 miles laterally apart!

As I said before, another example a knee-jerk, ill-considered, quick-fix reaction from Ops to which we have become accustomed.:rolleyes:

[Ahh-40612]

Apparently another occurrence caused by the 'Radar System' this morning on a trauma and turbulence filled LUS --please note, NOT just on North Sea.

2 targets right together south of Kent, one at FL340 and one at FL360, suddenly both show at 360 with frantic flashing of STCA.

Brown trousers all round for the 2nd time in a few minutes.

Overloads, aircraft descending without warning right on top of others due the turbulence, no flow, not enough staff but no demand.
Wrong again flow!

Get me out of this place!
:D :( :D :(

[Direct HALIFAX]

40612 -

Time to jump ship - TC are recruiting from LACC.

[HEATHROW DIRECTOR]

<<Time to jump ship - TC are recruiting from LACC.>>

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