Precision approach radar

[jack-oh]

Can any one enlighten me on how we got into this ridiculous situation with RPAR.

[Spitoon]

Doubt that I can help but right now I don't even understand the question. Care to enlighten us what situation we're talking about and what RPAR is (if it's not just a typo).

[Timothy]

Spitoon

I can tell you that RPAR stands for Replacement PAR (and is therefore presumably not a typo) but I have no idea what the "ridiculous situation" is.

I understood that it was being rolled out to RAF airfields and that ITT is the prime contractor, but presumably something has happened as happens to every other defence contract and surprises us afresh every time :rolleyes: :hmm: :zzz:

Bit like Homer Simpson being surprised every time a bad thing happens, but continuing to go back for more :p

Timothy

[Chilli Monster]

Bit like Homer Simpson being surprised every time a bad thing happens, but continuing to go back for more It isn't called the "Ministry of DUFFence" for nothing! ;)

[FWA NATCA]

Jack O,

We use to have a military GCA unit here at FWA, and believe me we threw a party when they finally left. You would give them a flight on base or final, tower would tell them cleared to land ONLY, and more than half the time they did something else, thus causing all kinds of havoc.

We do Survelliance approaches to three of our runways, but having to do one in an actual emergency is rare.

Mike

[Briney]

The ridiculous situation to which jack-oh refers is indeed quite remarkable, even for a defence procurement issue! The RPAR being all swept up and fancy has replaced the need for controllers to 'aim' the radar at the aircraft under control by working it out for itself. One of the problems that has been identified is that if you happen to be on a pairs approach and your wingman overshoots, the RPAR is likely to stay focussed on that aircraft and not the one continuing the approach to land. This could be quite easily spoil your day. In addition, other aircraft approaching the airfield could attract the atention of the RPAR and decide not to pay any further attention to you!

Recent instructions to military airfields have laid down criteria that must be applied for RPAR approaches under IFR conditions:

No other aircraft within 5 miles of the aircraft on GCA

No other aircraft within 2000 ft vertically above

No other aircraft to pass underneath RPAR traffic

Singleton approaches only

If these critieria are infringed by any track (known or unknown) the RPAR ac is to be broken off the approach. If these conditions cannot be met, units will offer SRAs instead.

So, Lincolnshire/Vale of York airfields, how are you going to get any successful talkdowns?

Of course this is equally a problem when looking at airfields as diversions. How would you like to be on a pairs actual diversion, short of fuel and trying to decide who is going to take the delay of a split for singleton GCAs. Perhaps you decide not to rely on PAR and choose the SRA option instead - Leuchars RW09 procedure minima 890', can't go there in Green or worse.

A quality, quality situation especially when you consider that this is only coming to light when the whole of the airforce has now gone over to this useless POS.

[spekesoftly]

Aren't the majority of operational Brit mil a/c and airfields now equipped with ILS, rendering RPAR an unnecessary/expensive/labour intensive luxury (if it worked!) ?

[M609]

The one with rotating nozzles don't, and they don't like the fact that the RoNAF binned the GCA 2 years ago when they are here on deployment. And yes, I belive a party was thrown the day they hauled it away here as well! :E

[Briney]

spekesoftly said

Aren't the majority of operational Brit mil a/c and airfields now equipped with ILS, rendering RPAR an unnecessary/expensive/labour intensive luxury (if it worked!) ?
No, I'm afraid they aren't. Of 27 military airfields with precision approach facilities, there are 58 PAR equipped runways against only 27 with ILS. Only 4 airfileds have dual ILS's; Aldergrove, Brize Norton, Linton On Ouse and Llanbedr. Equally, there are 5 airfileds with PAR only; St Athan, Culdrose, Topcliffe, Wittering and Yeovilton.

[Chilli Monster]

Briney

I think the boys and girls at EGAA would get very upset at being called 'military' ;)

[radarman]

Ho Ho! Yet another MoD cock up. I first joined in 1964 and had my first experience of military procurement when Their Airships bought some Beagle light aircraft (can't remeber the exact type) to ferry V-bomber crews about. By the time they had mucked about with the basic aeroplane it couldn't carry a full Victor crew. And so it has continued - Cossor 787, Argosy, Linesman/Mediator to name a few.
What alarms me is who dreamt up the idea of automatic aircraft tracking? If it was ITT, what idiot at MoD accepted the idea? If it was part of the MoD specification, what clown came up with such a cock-eyed scheme? Probably some jumped-up, over-promoted brown-noser who never got the hang of the servos. I bet a hundred smackers nobody took the trouble of asking the guys and gals at the coal face who have to use the kit. Yawn !!!! Nothing ever changes.

[AvOverthehill]

RPAR was a welcome replacement to the old CR62 - at least we can see the aircraft through the wx now - no more guesswork and fidling with MTI (must try imagination).

New rules out today for use of RPAR are a joke! Briney gives the basic details, but the signal from STC gave Units the power to set up our own rules. Strike command leading from the front again!

Now we have neighbouring units doing different things, because they have to, to make sure their a/c carry on flying.

After Ben McDhui - STC have found another (knee) JERK to make our lives a pleasure.

Roll on retirement!

[Spitoon]

Yup. I was right - I can't throw any light on the situation. But if only a fraction of the explanations here were right I'd have to agree that it's pretty ridiculous!!!

Glad I don't have to wear a uniform.

[Timothy]

Glad I don't have to wear a uniform.How can you say that when they have Mr Hoon as a boss? :} :yuk:

Timothy

[jack-oh]

As Briney has already described, the restrictions in force are fairly droconian. I have just spent all day trying to come up with a workable solution to 2 airfields with overlapping instrument and visual approach profiles. The pairs incident described is not the only occurance, I belive the one that tiped the scale was a Nimrod inbound to Kinloss RW26 with VFR departures underneath out of Lossie. The RPAR ditched the Nimrod track in favor of the Tonker and left the talkdown controller issuing instructions to an ac going 300kts in the wrong direction. The fact the kit was trialed in the Falklands may have something to do with all the problems not being ironed out well in advance of acceptance. These things are sent to try us.

[AvOverthehill]

To jack-oh

Question is - how many incidents like the one you describe, have happened?

As to the controller issuing instructions to the wrong a/c - then he's an arse! Even a chimp can see which way the talkdown a/c is going.

If the powers that be are worried about the data block going with another a/c, then why not terminate service at that point and use the good old "radar contact lost - are you visual with the airfield?" procedure that worked perfectly well with the old kit?

It really deosn't take the brains of a genius to solve the problem - instead of which, the whole military ATC system has spent the last day working out a series of differing and riduculous procedures to make the new STC rules work.

Milatary ATC has shot itself in the foot again, and made itself look a right bunch of Tw&*#s to the flying fraternity.

To Mike Jenvey

At my airfield we won't accept you or foreign a/c for PARs - you will have to do with SRAs and hope the cloudbase is not too low for you to get in

[Briney]

The problem is that "radar contact lost, are you visual with the airfield?" is fine if the answer is yes but if you happen to be on an actual diversion, IMC, with enough fuel for one IFR approach then that is not what you want to hear!

[ratt]

To answer the AVO,

IIRC 20 incidents since RPAR was introduced (about 3 and a bit years ago).

It seems that the 'take avoiding action separation on all traffic, known or unknown' is the knee jerk reaction to the fact that your data label may transfer to another aircraft in close proximity AND the aircraft you are talking to dissapear from radar.

The 'radar contact lost, are you visual' would seem the most appropriate action, however, this is a knee jerk reaction and not rational thinking!

I don't think that you can go finger pointing that the MoD is at fault on a whole (for once). From what I have seen the system is proven by the yanks and although maybe not the 'best of the best' it is by far adequate for the job with today's reduced budgets. I am no wiggly-amp type, but I am sure the boffins at RPAR HQ are checking their computer codes for a solution.

[Briney]

From what I have seen the system is proven by the yanks Their geographically wider spread of bases, often in relatively more remote locations may go some way to explaining why they may not have suffered the same problems - or have they?

[AvOverthehill]

To ratt

What is rational about having to break an a/c off his PAR approach when another a/c, which Director has just co-ordinated with his mate on Zone, infringes the 2000ft/5nm rules.

Seems that 500ft/3nm co-ordination in RAS conditions is OK on SRE but not on RPAR - where's the logic in that?

[Whipping Boy's SATCO]

Being on the periphery of this discussion, I firmly believe that there are a number of very credible and capable ATC staff officers who are desperately trying to resolve this problem that they have inherited. I am sure they would not have implemented "draconian" restrictions without just cause.

PS. Having seen a video of one of the "incidents", I personally would be VERY wary of using the equipment.

[jack-oh]

To elaborate on what I said earlier the RPAR does not give you 2 contacts with only 1 set of information. It drops the first completely and then locks up the second, I agree that in severe cases any "chimp" could tell this has happened however consider this; a pair do an approach and at 2 miles one of them breaks off, the RPAR follows that one and drops the one actually carrying out the approach. Both ac are IMC, the second ac executes a missed approach and you say to the ac that you can see "Well above glidepath acknowledge" he acknowledges and sticks his nose towards the floor. All of a sudden, another track appears on the RPAR well below the glidepath. The powers that be knew this could happen but did nothing about it. The restrictions in place make it almost impossible to do a PAR in the open FIR they also open up a can of worms regarding ac doing instrument approaches in VFR rather than IFR. It is interesting to note that civil and foreign Mil ac are considered to be flying IFR irrespective of met conditions whilst carrying out an instrument approach yet Brit Mil ac are not. This has brought the full glare of all flying units and their commands upon ATC and the manufacturers of RPAR. This is undoubtedly deliberate and will hopefully ensure a rapid solution.

[Proletarian]

I believe that it is little short of a complete disgrace that RPAR was installed and introduced into service without clear guidelines being promulgated to the units concerned. Such a radical change should have been trialled in this country by a group of experienced controllers, instructors and examiners, who should then have produced a complete users guide - IN ADVANCE of the equipment being installed and introduced into service anywhere else.

All the experience gained by MPA in the use of RPAR appears to have been 'lost' in the move of MATO from Hillingdon House to HQSTC. As I understand it, RPAR was then introduced into service with little or no guidance from HQSTC because it was just another PAR system. Had a serious incident occured, I dread to think what a subsequent BOI would have made of the whole sorry shambles. And who would have been 'stiffed' - why the controller and SATCO of course!!

We shouldn't forget that RPAR is essentially a component of a complete system, which should have a search radar element - essentially RPAR is the full system but with the search radar element missing. We replaced a dedicated PAR system, the SLA3C, with another dedicated PAR system, the CR62. Both systems were essentially 'dim' systems where the controller determined exactly what was displayed. Now we've ended up with a bit of a bodge job, which is supposedly 'intelligent', yet makes stupid decisions, and nobody has much faith in. Isn't progress a wonderful thing!

[spekesoftly]

"A complete system" - like CPN4/MPN11? (Ex lease/lend) - time to dust them off again? ;)

[ATC-OPS1]

As a Controller who has used RPAR for over 2 years at 3 stations without any problems, I feel I must respond to some of the wild comments. RPAR replaced the CR-62. The CR-62 was either continually defective or when it worked could see nothing but clutter.

The RPAR is a fantastic PAR will a superb availability record nearly 100% for all stations. It sees things we never ever saw on the CR 62. It makes my life so easy with it auto-tracking, clear display and status reporting.

Where we (the RAF) fall down is we haven't updated our 40 year old procedures to deal with this 21st century PAR. Come on Strike pull your finger out and bring us up to date.

On the few occasions that I have had a defect the ITT folks in Basingstoke have responded very professionally and fast - how refreshing when you have to deal with AMS and Brit Aerospace on other equipment.

Stop whinging and be thankful we have this wonderful piece of reliable kit. Strike Command get your SATCO's together and bring our procedures up to date.

[Briney]

used RPAR for over 2 years at 3 stationsJeez, can't you hold a job down?!


superb availability recordIt's always ready to abandon you as you approach DH


we haven't updated our 40 year old procedures to deal with this 21st century PARHow do the procedures, however old they are, make a difference when the kit is fundamentally flawed?


Stop whinging and be thankful we have this wonderful piece of reliable kitAre you sure about this, you don't work for ITT or DPA do you??

[normally left blank]

Spekesoftly

"A complete system" - like CPN4/MPN11? (Ex lease/lend) - time to dust them off again? "

They still work fine over here! Terma updated them about 15 years ago. They never fail. So ask them, if they are not too busy selling death and destruction.

The new ITT PAR, if it worked as advertised!, is an old PAR-controller's dream. No "weather" to bother about. Much easier to work with.

FWA

Sadly USAF PAR controllers became something of a joke in the 70'ies/ 80'ies - at least here in Europe. Pilots didn't trust them, and avoided them when possible. In fairness one in Germany saved a Danish two-seater Draken once. It was snowing and the pilot(s) couldn't believe that the white! in front of them at minima was the runway. They believed him the second time around!

Best regards

[Whipping Boy's SATCO]

ATC Ops 1, you are of course, mostly correct. The kit doesn't break down, no more servo/gain and you don't see much in the way of weather. Only one minor snag, it appears to be able to completely dump your ac (including the "primary" return) in preference to another that, up until the transfer of label, hasn't even appeared on the screen! Now I call that a technical problem.

[ATC-OPS1]

Another farce the "Bird" radar at Kinloss. Wouldn't see a bird if it landed on the antenna.

Over 18 months late and still not delivered.

In meantime using CR62 as bird radar, don't make me laugh.

Another AOS cock-up assisted by Strike and BG.

[jack-oh]

Apparently, the RPAR works to specification. However, no one quite knew what that specification was. It apparently works by creating a box around the tracked ac, this box of airspace is quite big and if anything fly’s through it there is a possibility that the system will be corrupted, hence the present restrictions. The questions that need answering now are: How big is this box? Can we make it smaller? If we can make it smaller will this still mean that the system can be corrupted? If the answer to that is yes, what is the probability of this happening? Would the controller viewing this data be unaware that a problem existed?

As far as I can determine on every occasion there has been a severe problem the controller was aware. Obviously, this does not mean that serious problems have occurred and the controller wasn't aware. There are known unknowns and things we don’t know about, as Donald Rumsfeld would say.

However, 20 reported incidents out of countless thousands of approaches aren't bad odds when you consider the amount of times you had to reset CR62 or lost the contact in radar clutter. Nothing in life is a dead cert and I do get the feeling that RPAR has been shunned by the Ludities and these incidents have been blown out of perspective. However, a problem does exist but will any fix cure the problem totally. It certainly won’t make the system a primary radar, and therefore some form of tracking "BOX" will still be required. If restrictions still exist after all due process then it is not worth keeping. At the moment, it effectively means that PARs cannot be provided when you actually want one. If this is to remain then we need to think fast about a Replacement-to-Replacement PAR.

[Hard Bernard]

It certainly won’t make the system a primary radarForgive me if I'm wrong Jack-oh but isn't this system a primary radar system, albeit a processed form? Otherwise you would only be able to offer a talkdown to an aircraft equipped with a serviceable SSR and separate them from other SSR traffic.

[jack-oh]

Yes it is a primary radar in that it sends out a radio pulse that is returned to the radar head. However, it is then processed and synthetically displayed. What you see as a radar controller is an abstract picture not a true reflection as was the case with CR62 or MPN23V. In this way weather returns may be displayed but not impinge on the clarity of the picture you are looking at. To have a true primary picture you get it warts and all. This would not work with RPAR as all weather returns would then be displayed as * rather like aircraft, the system would then be infathomable. In a previous life I worked with a lot of missile tracking radars which had a very small field of vision to prevent the possibility of loosing lock. However they had a limited range and very narrow beam. To modify RPAR to that level would cost alot of sheckles, if any other defence contract can be used as an indication. My point is, if after months of trials and boffins scratching their heads and money men rubbing their hands we end up with something that is so restricted that it is practically unusable, we should attempt to identify an alternative that works and could be installed quickly.

[Briney]

Unfortunately, 'only 20 reported instances' adds up to a very big and bad sense of distrust. If this equipment was in the early stages of its' development then issues like this may be expected and allow time for the faults to be cured. But after the entire(ish) RAF has rolled it out and the fact that it is already in service with USAF and the Brazillians does not inspire confidence that the issues can be resolved.

It would be interesting to hear from someone who has engineering or in-depth project knowledge (if there is such a person!) to find out if this situation is recoverable with the current kit. The current depth of aircrew feeling is running against this system that seems only to promise an very uncertain future.

PARs are great for aircrew, especially single seat, when recovering a jet in emergency but I want to know that it is actually me being talked down and not the mate who's been sheperding me back and breaks off approaching DH - "well above grlide path"!

[ratt]

What is rational about having to break an a/c off his PAR approach when another a/c, which Director has just co-ordinated with his mate on Zone, infringes the 2000ft/5nm rules.

I totally agree. But we will have to trust those in higher places for now. The rules may change again by lunchtime.

I would like to see this amount reduced and an element of the 'operators discretion' in certain cases. After all, even with CR62 you could loose the landing aircraft and see only the overshooter sometimes.

SRE is being used but of course being a non-precision approach the MDH is alot higher, therefore precluding arrivals on the more grotty days.

[glider insider]

It would seem that a little knowledge is a dangerous thing!!!
I DO NOT KNOW EVERYTHING!!! but in answer to some of the points raised earlier.....

changing procedures... yes, a possibility, but in some airspace this will prove incredibly difficult. Think of a certian Lincolnshire station that has a low level corridor crossing at 10 miles finals and three other airfields within 15.

Pairs Approaches.... Now this has been known about for some time.. and yes on an actual diversion, short of fuel etc etc it could prove a problem... but any decent director should manage to split a pair and provide 4 miles track distance between them to land.. and if an extra 4 miles results in an incident, perhaps we should be looking at a problem in the flight planning department?

The fix.... there are many suggestions being bounced around, and I'm sure every crewroom in the country is talking about this one... perhaps a realistic, but possibly expensive resolution would be to reintroduce the software to allow SSR data as well, which would hopefully stop the target jump problem.

From talking to the contractor at my unit, he pointed out that the contractor have supplied what was asked for, a fully functioning ICAO approved radar. It would seem, sadly, that the fault lies on the procurement side. Perhaps time will tell!!!!


and now I wait to be blasted by just about every other PPruner out there!!

[Hard Bernard]

What about Briney's point about sheperding another aircraft back, bit difficult to do that with 4-5 miles separation.

And please, please tell me that the procurement process is a little more than, "Can I have a fully functioning ICAO approved radar please"!

[glider insider]

Briney,
the shepherding point is certainly valid, and one I overlooked in my earlier post.......

the ICAO bit I should have made clearer in my first post.
Obviously, we didn't go and say "we want an ICAO radar" in the procurement process. We said what we wanted in a more detailed fashion, and this list of requirements has been met by the contractor, in a manner that uses a radar that is not new technology, but happens to be a product that has been used elsewhere succesfully and is ICAO approved.
Where it would seem we might have gone wrong, is in our specification of requirements, not actually thinking about the other "factors" that affect our PARs, such as proximity of other traffic and pairs etc.
The sad thing is the system now installed had the option of also using SSR (apparently a software issue) and being a full radar with a range of 35 miles ( a hardware issue), but we stated we only want a PAR replacement so dont bother with the other stuff.
It is a shame that the replacement of the CR62 didnt involve a look at all the ATC kit now in use, because I believe the watchman system is coming up for replacement, our comms system is quite dated and surely there is a better system to replace ET.

As it is, being the cynic I am, the MOD will prob pay for a costly fix to the RPAR, thus using the money that might have been earmarked for comms or radar replacement..
oh well, the glorious history of defence procurement continues!!

[rej]

As one of those involved in the 20 incidents, I think the inject from STC is fully justified. Why should we operate a piece of kit with little confidence (in the kit - not our abilities) when pilots need to have 100 % confidence in it? I can honestly say that in my current post I see a lot of PARs . The CR62, although not the best peice of kit in bad weather (although the knobs and tits , if used correctly could sort that out), never caused as many break-offs due to equipment failure as iI've seen with RPAR. On some days it's been like a PAR exercise in Advanced at JATCC!!!

ATC-OPS 1, I look forward to discussing, over a brew, why you do not seem to share the same views as most at the secret Wiltshire airbase. Yes RPAR does see things the CR62 did not (like GAT on L9!!!!) - is that a good thing?

How many out there are fed up with MTI failures, data tag jump, target split, etc. Lets get the kit working so that we can move on.

[normally right blank]

Did the RAF ask something to be "deleted" from RPAR?

What was saved - moneywise?

Glad they (ITT) are hard at work! :O

Still som "Gilfillan" name plates in our equipment :D

Best regards

[KPax]

At Lyneham they ask aircrew ' do you want a VFR or IFR PAR' if VFR they ask them some questions and then carry on with the talkdown. Class D what a wonderful thing. Must make Lyneham the obvious place to go for training.

[rej]

KPax

Of course Lyneham is the place to come for training!! (That statement is bound to start another thread out there !!!)

The RPAR procedures re IFR/VFR are not due to Class D airspace - they are due to the restrictions in place. Any aerodrome can ask a BritMil singleton if they will accept a VFR PAR thus the 5nm/2000ft separation will not be required. Our Class D is 2nm to the north of the final approach course and 6nm to the south; as you can see under IFR we still need to terminate against the unknowns to the north or over the top (patterns flown at 2000ft E vs class D at 3500 ft H).

If you wish to apply the same then give someone a call at the secret Wiltshire airbase and I'm sure we can steer you in the right direction w.r.t local orders etc.

If not, then send your traffic to us and we can do even more training.

Rej

[Pie Man]

Rej

The RPAR procedures re IFR/VFR are not due to Class D airspace

If this is not the case how are you getting round the rule that civilian and foreign pilots are always to be considered IFR.

Below quote from EGDL NOTAM.

PILOTS OF FOREIGN AND CIVILIAN ACFT ARE ONLY PERMITTED TO FLY PAR APCH UNDER VFR

Bye

Pie

[rej]

Pie

As I said, any pilot of a Brit Mil ac could fly a VFR PAR.


The first NOTAM you quoted was a simple, yet significant, typo that was rectified within a few minutes. The second referred to IFR PARs for foreign and civ pilots.

Hope that clarifies any misunderstanding.

Rej

[Pie Man]

Rej

Sadly the revised NOTAM does not appear to have been issued - check of AIS site (1600 on 19 Feb) still says:PILOTS OF FOREIGN AND CIVILIAN ACFT ARE ONLY PERMITTED TO FLY PAR APCH UNDER VFR

Regards

Pie

[Edited Due Typists Stupidity]

[KPax]

In the short term why don't we switch the tags off, and do a 'Talkdown' on the track only, using the RPAR and the WHI function. Most qualified controllers could give a safe and accurate talkdown on a primary only contact.

[Pie Man]

KPax

I don't think it's quiet as simple as that, as the dot is not a primary return but a processed return, so the problem still occurs with the tags off.

Pie

[Chateauneuf]

It's always a pleasure to see the promotion of two people for every half brained idea - one to bring it in - the other to fix or remove it!

[tired-flyboy]

In the words of many an 'ehm' esteemed instructor at JATCC

HOW SAFE IS THAT!!!!

Glad i don't have to do PARs any more!

ps

God how i miss those duel talkdowns, 4mile spacing in Green or Amber.

Trying to do servo and gain for the 'chap' next to you and wondering whether or not they could see their track!

then the supervisor comes over and tries to tell you that after these your going to tower to relieve the controller as they need a break!!!!!!!!

Why is it always s:mad:y weather during JMC???
:ok: back in the box i go! :ugh: