GPS technology breaks Perth Airport gridlock...?

[Capn Bloggs]

from The West:

GPS technology breaks Perth Airport gridlock

11th May 2009, 6:00 WST



Air traffic control delays at Perth Airport that have caused costly bottlenecks lasting up to 45 minutes have been eliminated by new streamlined procedures.

They take advantage of the latest navigation technology using a global positioning system with pinpoint accuracy to just a few metres — instead of kilometres.

Congestion at Perth Airport has been made worse by the morning rush period between 5.30am and 7am when up to 70 aircraft depart and arrive on peak days.

Air traffic control provider AirServices Australia launched the Western Australia Route Review Project in 2002 to clean up WA air routes and air traffic control procedures that had their origins in the 1940s.

The addition of GPS capability on modern commercial aircraft has allowed much closer separation between aircraft.

Previously, the navigation tolerance between GPS-approved aircraft was a 14 nautical mile buffer around each aircraft.

This meant that two aircraft had to be 29 nautical miles apart — with the extra one nautical mile allowance for error.

Unlike the US and Europe, most of WA has no radar coverage and error tolerances had to be built into the air traffic control system, which relied essentially on intended speeds and course and pilots reporting position.

Controllers at Perth Airport had to keep aircraft at least three minutes apart on take-off, which meant the maximum aircraft able to takeoff per hour was about 20.

The new separation has been reduced to 15 nautical miles and combined with better co-ordination of aircraft that will use different flight tracks, the number of take-offs has effectively doubled.

At the same time, Perth Airport has completed a new taxiway that allows aircraft faster access to runway 06 — the shorter cross-runway that is used in strong easterly winds.

This taxiway saves at least five minutes each departure.

Perth Airport now has on average about 350 arrivals and departures a day.

But on peak days of Tuesdays and Thursdays the number is closer to 450 a day, making it the third busiest capital city airport after Sydney and Melbourne.

GEOFFREY THOMAS



While WARRP has done wonders for "smoothing" operations in WA outside radar coverage, and the new taxiway to the 06 threashold helps departures (by 5 minutes? :cool:), the GPS standards mentioned do very little for the main problem at Perth: the lack of a second runway!

The airborne holding periods and slot times for departure certainly haven't been "broken".

Call me a sceptic, but I reckon this is a GT peace-offering to WAC, letting them off the hook over the second runway after giving them a caning a few weeks ago about terminal delays.

[Dick N. Cider]

Interesting to note:

Air traffic control provider AirServices Australia launched the Western Australia Route Review Project in 2002 to clean up WA air routes and air traffic control procedures that had their origins in the 1940s.

The new procedures, of course, had their origins in the 1940s - as will anything that follows...

Why do we even feed some journalists?

DNC

[Bullethead]

Air traffic control provider AirServices Australia launched the Western Australia Route Review Project in 2002 to clean up WA air routes and air traffic control procedures that had their origins in the 1940s.

And despite this recent review there are still air routes into YPPH that have no connecting STARs and also STARs that have the name of another STAR as the transition identifier.

If that isn't a setup at the end of a long day in adverse conditions I don't know what is.

Regards,
BH.

[Capn Bloggs]

And despite this recent review there are still air routes into YPPH that have no connecting STARs and also STARs that have the name of another STAR as the transition identifier.

If that isn't a setup at the end of a long day in adverse conditions I don't know what is.
Have you put in a suggestion to AsA to rectify this? RAPAC? None of the routes I fly into Perth fall into the category you mention, well none that I can remember...

What was achieved by PM, GW and their cohorts with WARRP was nothing short of exceptional, IMO. A few ragged edges but a terrific outcome overall. Pity about the clankup at the runway...

[alidad]

:rolleyes:I know how to fix it........bring back waypoint ALWYN.....that'll sort things:sad:

[Bullethead]

Paperwork is in the system Capn Bloggs. :ok:

What was achieved by PM, GW and their cohorts with WARRP was nothing short of exceptional, IMO. A few ragged edges but a terrific outcome overall.

Agreed, but why not get it all correct.

Regards,
BH.

[Baileys]

It would want to be good for 7 years worth of work....if that's what they are saying.

[Capn Bloggs]

Al,
I know how to fix it........bring back waypoint ALWYN.....that'll sort things
He's still there, over the rubbish dump! :ok:

[Bug Smasher Smasher]

Capn Bloggs said:the main problem at Perth: the lack of a second runway
Um,
1) 03/21
2) 06/24
:confused:

[B767MAD]

Smash Smash , I think bloggs was thinking along the lines of 03L 03R etc

Sounds like a few have flown the CONDL1 instead of the GOSNL1 also.

[Capn Bloggs]

Thank you 767. Bugsmasher, two lengths of bitumen that cross in the middle are not classified as two runways in this context, if you get what I mean. :ok:

CONDL v GOSNL: wax job required?

[Icarus2001]

Fair point though Bloggs, would be a huge improvement if in the morning one could actually take off on one of the strips of bitumen RWY 24!. For goodness sake 24 with right turns and 21 with left turns would make a huge difference to flow rates.

But no. Noise complaints. So we spend millions of man hours, engine hours and burn more fossil fuel to keep the noise down at what..7-8am when everyone is getting up and having breakfast or driving to work anyway.

Sigh:ugh:

[flyingfox]

Conclusive proof I would think that GT is a discredited journalist who writes rubbish about aviation for a living. What on earth is he on about? There must be something he wants from either ATC or WAAC staff. This article is (yet again) complete nonsense.

:mad:

[westausatc]

There have been a few instances where pilots have flown CONDL arrivals instead of GOSNL. Unfortunately, leads to the controller being stood down until they work out what happened. Supposedly fix is in the system... CONDL will become CONNY or something like that is what I have been told. Hope it fixes it.

And just like every other airport in the world, the lack of bitumen is what causes the delays. There have been no changes to the arrival rate for years so this airspace change has done nothing to help that. The reduction in traffic we service is what has helped.

[west atc]

There have been a few instances where pilots have flown CONDL arrivals instead of GOSNL. Unfortunately, leads to the controller being stood down until they work out what happened.

Gotta love the Aussie way of doing things, something went wrong must have been the controller's fault. Having now worked in another country, it seems the rest of the world only cares whether you kept 3/5NM or 1000FT.
If something went wrong but there was no separation issue then the easiest thing is to ask the pilot whether they understood the clearance correctly, if they believe they did then it gets recorded but with no fault put on the controller.

It makes life a lot easier when you don't go to work worrying about every little minor thing that can go wrong, especially with feeding the machine and actually spend more time focusing on keeping the aircraft apart.

And just like every other airport in the world, the lack of bitumen is what causes the delays. There have been no changes to the arrival rate for years so this airspace change has done nothing to help that. The reduction in traffic we service is what has helped.

It's not always the lack of bitumen that causes the delays, I had a look at the arrival stats shortly before I left ASA and the amount of arrivals very rarely gets near the expected rate. This isn't always the fault of the approach controllers however, it is partly caused because the controllers are too afraid of the aircraft getting close to the required separation standard and the 'bit for mum' put in can help cause the delays. Where I work now 2.9 is still 3 as long as the aircraft are not put in a dangerous situation. If you are talking final approach, at 160-200kts GS on final, 2.9NM is still safe. There were many times on Perth Arrivals that I saw 3 aircraft within 30NM of the field, this is incredibly inefficient.

[Mr. Hat]

7-8am when everyone is getting up and having breakfast or driving to work anyway.

There are some long term unemployed people that you might wake up Icarus. We need to keep them happy.

[Dick N. Cider]

Particularly nice touch that the land reserved for a parallel runway is now rapidly filling with industrial buildings on 20 year leases. The theory being - "Tell us if you want that runway and give us 25 years notice to end the leases and build the damn thing..."

Just goes to prove that airport operators aren't interested in aviation. It just gets in the way of developing all that lovely flat industrial land relatively close to capitol cities. How many more DFOs do we need?

DNC

[kimberleyEx]

Dick N Cider.

You hit the nail on the head!

Yes WAC has the airports best needs at heart.... Just not the Aviation needs!

Regards.

K-Ex

[Joker 10]

If you look at the major airports in USA and UK you will find the airport land is generally utilised for commercial property where ever it can be safely outside exclusion zones, otherwise the landing/handling fees would be manifestly higher.

A really good example of offsetting costs is the work being done at Jandakot.

[Icarus2001]

I am no big fan of WAC however...Particularly nice touch that the land reserved for a parallel runway is now rapidly filling with industrial buildings I am not sure that this is true. Have a look at this link to the WAC Perth Airport Master Plan and check out the plans and aerial photo, you will see that the racetrack is in the way but not the distribution centre, as far as I can see.

Happy to be corrected.

http://www.perthairport.com/getfile.aspx?Type=document&ID=48190&ObjectType=3&ObjectID=3387

[Mr. Hat]

USA and UK

Yep how bout we do everything the opposite to these two places and we might end up with a half decent place to live and work...oopps too late.

[tomcat264]

You want a $20 million parallel RWY for 20min use every day?? what colour is the sky up there in your world?

[clark y]

Not being too familiar with Perth at peak hour, but do they do LAHSO very often or use multiple runways for departures i.e. 24/21 from taxiway J?

[Chadzat]

Multiple runway departures when RW03 & 06 are in use. Then usually single runway arrivals RW03.

Single runway departures when 21 is in use and multiple runway arrivals RW21 and 24.

Half the problem is the taxiways around the Qantas and common user domestic terminals atm. All it needs is a QH heavy to push back off its bay and if 21 is in use, everything behind them have to stop and wait for them to commence taxi. Hopefully the imminent relocation of the fire station will help and they can maybe build a parallel taxiway.

[Icarus2001]

You are close to the mark there clark y. Morning departures often only use 21 (nil or little wind) when 24 could be used. The reason given is noise abatement. It would be reasonably easy to create a departure off 24 which required a right turn to clear most noise sensitive areas. Having a second runway for departures would make a huge difference to flow rates.

As for LAHSO, I never see it in use over there when I arrive or depart. Seems to have been a waste of time and effort installing the lights.

[-438]

I agree 24 for departures is the only cost effective and practical idea.
How much fuel is wasted on the ground and in the air around Perth, not to mention the rest of Australia.

Global warming is the greatest moral challenge of our time.

Except for votes from people who buy houses or land in the vicinity of long established airports.

[Jabawocky]

Global warming is the greatest moral challenge of our time.

No, thats been cancelled.

[YoDawg]

Seems to me, if they re-commissioned 11/29 they'd have a significant number of the prop-jobs departing after very short taxi and also a smaller impact on aircraft waiting to line up full length of 21.

But what would I know..... :eek:

[Mr. Hat]

How bout putting the slow prop jobs at jandakot. Metro and Braz keep up okay but the rest..well..:yuk:

[ozineurope]

LAHSO - problematic cause some companies could not guarantee that they would use it. One uses 2300m in ML but wont change SoPs to use 2247m in Perth (03 landing). Only useful on 03/06 configuration and the nature of Perth traffic being what it is...most of the arrivals are the subsequent departures.

11/29 - too many taxying aircraft to ever be a runway again.

24 DEPS - taxyway structure would need a big redesign. = $$$ to be spent on non commercial infrastructure by WAC = never happen. Also the NIMBY factor in play. But if you could get 24 used by F50/Bras/DASH types and jets off 21 ...hmm. Then the delays would happen airborne as the jets caught the props but procedures could be designed with separate jet/non jet SIDs so the passing levels were reasonable and the tracks did not come together until about 30 track miles.

Also would need the RAAF to relinquish levels below FL160 for transit closer to the coast for off set tracking of the segregated routes. Been there done that ..failed!

[Nautilus Blue]

umm... Ph has a slot time system for departures because the tower can fire aircraft off faster then the surrounding airspace/procedures can cope. An extra departing runway would make no difference. If you want to see the problem I would beg you to arrange a famil to ML centre on a Tue, Wed or Thurs morning to see the outbound push.

[ozineurope]

So Nautilus the great white hope that was WARRP has not really changed anything but the names then?

Nobody bothered to look at sectorisation, staffing, locating the stacks away from the routes etc etc.

Why am I not surpirsed that WARRP delivered nothing except changed SIDs/STARs, not surprising really when industry and RAAF were only involved at the 11th hour.

[Nautilus Blue]

No WARRP changed a lot. It gave us a system that can't cope with traffic levels/type mix, instead of a system that couldn't cope AND was going to kill people sooner rather than later. No route structure can handle ~40 departures in an hour, ranging from F50 to B717 into 135 degrees of arc requiring 5nm separation.

The RAAF were involved in the first 2/3(?) WARRP schemes, which was why they failed. The final WARRP was implemented because it adopted a fundamental design philosophy of "the RAAF are going to give us nothing, deal with it". (As an aside, rumor has it there is only one northbound SID, GURAK# for all types, rather than one for jets and one for turbos because the RAAF thought two SID's was too complicated.)

However, to be fair the RAAF have nothing to do with the morning outbound push, they are still in bed at that time of day :).

As for consulting industry, why bother. They will all say they want unrestricted climb/descent, minimum track miles and no vectoring off track. We don't add height requirements and track miles for fun.

Sorry to whine on and on, but I think if we can't provide a perfect service then we should try to explain why (even if it does sound like a typical Public Service 'Not my fault' ).

[ozineurope]

Hey NB I was closer to the system than you might have guessed!

I am well aware of the foibles of Perth airspace and the route structure. There are many route structures that accommodate a lot more traffic than Perth experiences in an efficient (debatable) and safe manner. The traffic out of FRA is quite considerable and this is melded with Stuttgart, Munich, Berlin and Hahn departures also. Coupled with the overfliers who are transitting to UK, Russia, Poland and other Euro zone destinations the piece of sky above Germany would have the equivalent of Tues/Wed/Thurs traffic all combined into one 2 hour period.

My main disagreement with WARRP was that there was a lack of focus and no defined outcome. You may be surprised that industry involvement at the high end has several advantages and the, yes the focus is on minimising track miles/VNAV etc, but the dealings that I had with industry were productive and gained several advantages over a 'here it is take it or leave' process. But as a controller my focus was on minimising track miles too, with systemic safety at the forefront.
So dont design 2 STARs that are almost identical except for the last 20 miles and then give them similar names (CONDL v GOSNL), the whole process was designed to fit a time line rahter than undergoing a rigorous safety assessment and delivering the best outcome for ATC and airlines alike.

[ozineurope]

Oh and as to RAAF involvement -

the squadrons were involved but no one above the base CO at Pearce were consulted. The changes that ROTAP brought about involved the DCAF and the GM ATS being involved in the discussions. I am not aware of any such high level involvement in WARRP.

Perhaps this is why ROTAP gained so much RAAF airspace and WARRP got nothing but a few miles to the south. Remember that the SIDs and STARs were designed on the premise that RAAF were H24 and as such had to be convoluted H24 also.

[Nautilus Blue]

Hey NB I was closer to the system than you might have guessed!

I know. I'm guessing you are one of the three reasons we were short staffed about 3 months after WARRP :p ?

There are many route structures that accommodate a lot more traffic than Perth experiences in an efficient (debatable) and safe manner.

Everybody says that so it must be true. Nobody has ever explained how though.

and no defined outcome

Yes there was. We must do something, this is something, therefore we must do this. :)

the DCAF and the GM ATS being involved in the discussions.

You remember who the current GM ATS is. Do you expect he would involve himself in something as petty as airspace design?

the whole process was designed to fit a time line

There was an urgency to it though. After three years of lots of hard work for no results while the traffic got worse the chances of it going badly wrong one day were growing. What we got is far from perfect, but its miles better than what it was.

In an ideal world WARRP would have been an quick interim bandaid, followed by a serious project using people with airspace/procedure design expertise and experience (esp from overseas) with testing and feedback from pilots and controllers using a high fidelity sim. In reality, we were luck to get what we did. Now if it has been a NSW-RRP ....

[ozineurope]

Yep. But watch this space for a Lazarus!

My only recommendation is that a PIR should be done now, and a white sheet approach taken. (AGAIN) The traffic levels appear to be still increasing with no real easing evident. The PIR as you suggest must involve current controllers, industry reps, RAAF and people from PDS from the get go.

This time do it because it can be done, not because it must. Dont let the noise lobby get the last say, that is why we cant use 24 for departures or 06 for arrivals. Tie it to hours of the day if that is what it takes. Get people to think laterally and outside what we have always done. Instead of H24 procedures - make it HRAAF, after all they share the room with the TCU so you'd have a pretty good idea that they were open and the mitigator for the one that slips through the cracks is the real time coordination that we can do. Use the bloody TAAATS route function to catch the problem before it goes too far.

Ease the workload of the controllers and aircrew by removing the necessity to cancel the bloody SID on every aircraft that gets airborne between 5.30 and 7.30am by assigning SIDs (non RAAF) or SID(R) outside RAAF hours. Night flying is easily accommodated by just reverting to HRAAF departures.

FUA must still be on the agenda - it must be given a kick. This is where industry are useful, they have far more power than lowly ATCs - even at GM level. Access to Pearce TRA is a must this will only be gained by forceful and high level negotiation. Even if it is a stepped access. For Pete's sake Luftwaffe and RAF have NO exclusive use airspace at all and they fly a lot more often and a lot faster than the RAAF.

I could go on and on, but no one listened to me in 2008 so what would be differnet this year!

Keep them apart and keep smiling!

[Capn Bloggs]

I don't know much about the ATC politics/aspects of WARRP, but I fly in it every day and I'm happy. Things appear in the cockpit to be much more organised. Sure we get stuffed around occasionally, but that makes life interesting. On only one occasion have I flown the full GURAK off 03 - the RAAF do seem to go out of it's way to track-shorten us.

As for the 15nm GPS standard and one-way routes, that is singly the biggest risk-reducer I have seen in WA for decades. Brilliant. If the boys did nothing else right, that earned them a gold medal.

[ozineurope]

Capn - but it good have been sooo much better.

Glad to hear though that the changes are working and have made a positive difference.

[flyingfox]

Maybe for the not to distant future we could lobby the Feds for a 21 parallel runway to suit turbo props only. Much cheaper than a full blown runway for all types of aircraft. Also using left and right turns for aircraft departing on different routes could clear departing traffic more quickly. What is wrong with joining some SIDS from over the top after a turn. There are alternatives if the tower is given some airspace.

[Awol57]

The issue when I worked at the tower wasn't how quick we could launch them, but how quick the surrounding airspace (mainly centre) could accept them. Given the lack of radar coverage outside of about 90nm (ovbiously depending on height) meant we had to have at one point, 2 mins between departures on the same SID. That went away but we can still launch them quicker than Centre can accept them. Would more radar help? I don't know, I am but a simple tower controller :)

[flyingfox]

Awol! More and better radar would be great. An extra northerley SID for diverging aircraft would be great too! (Though Bloggsy's point is noted.) The worst problems arise during IF conditions at the airport and fog on the tarmacs is almost 'terminal' to all ops. A turbo prop runway and faster launches are still needed though.

[Capn Bloggs]

More and better radar would be great.
With mandatory ADSB above 290 from 13 Dec 2013, things will run a little better. Plop an additional ADSB tower on the big hill north of Tom Price and all would be sweet. :ok:

[Nautilus Blue]

a 21 parallel runway to suit turbo props only

and

using left and right turns for aircraft departing on different routes could clear departing traffic more quickly

are mutually exclusive if you think about it. Awol57 is right, the tower can already depart aircraft faster then area can deal with them, so another runway would not help departures at all (arrivals are another matter). Radar coverage is not an issue, the problems occur well inside coverage. ADS-B is already making things better, and will get even better when its mandated, but it won't help this. (As an aside, it won't help sequencing inbound because PH controllers inc the FLOW cannot see ADS-B tracks)

Remember, as soon as you call departures from tower your aircraft becomes 3 miles wide and 3 miles long. When you call centre its 5 miles wide and 5 miles long. Also, inbound traffic takes up the same amount of space. Then complicate the issue with different speeds. You can't have a B717 five miles behind a B146 (or anything 5 miles behind a F50 :)). It's a shame we can't post a video of an outbound push, because its so much easier to show then explain.

[flyingfox]

It is 'kind of ' implicit that a parallel turbo prop runway will also help with arrivals! (I didn't think I'd have to spell that out.) It would also help with departures simply because a Heavy or fast jet won't be waiting to line up (or land) when a Metro or similar is occupying a slot. (Spelling it out; - parallel ops.) It helps even more in IFR conditions when spacing is so critical to Controllers and arrivals and departures slow even further. The whole point is that if aircraft can be launched and 'retrieved' at a greater rate, then that should actually happen. Change the SIDS, STARS and routes to make it work. This requires 'action' instead of excuses. Perth does not have the worlds greatest density of air traffic, nor is it surrounded by dozens of other large airports. If you can't get enough routes and separation of aircraft in an airspace like WA possesses, then some department, person or persons are not capable of doing their jobs.

[Icarus2001]

Here is a link to the Perth Airport master Plan 2009...

http://www.perthairport.com/getfile.aspx?Type=document&ID=61855&ObjectType=3&ObjectID=3981

Have a look at the size of the proposed parallel 03/21 that is shown.

Then have a look at where they are building warehouses.

[Nautilus Blue]

The whole point is that if aircraft can be launched and 'retrieved' at a greater rate, then that should actually happen.

I couldn't agree more. I'm trying to explain why they can't (departures anyway). Sometimes people say they can't because they are lazy or incompetent. Sometimes its because they can't. I'm not suggesting for a second that PH is perfect or even optimal, but I've not seen a specific proposal to improve it yet.

Parallel rwys help with rwy sep, thats all. If a B717 is behind a metro, it doesn't matter if it takes off from the same rwy, or a parallel one, it still has to go around the outside, by 3 miles. One landing, one taking off doesn't help the twr get departures away any quicker because they can already get departures away too fast. For departures, rwy capacity is not the limiting factor, nor is it the route structure, it is the physical volume of airspace. There is a limit to how many 5 mile circles 1000 feet high that you can put into a given volume of airspace.

Its an interesting exercise to try designing a SID/STAR scheme yourself. Draw a 40 mile circle, airport in the middle. On the circle, between 10 o'clock and 5 o'clock, mark 3 sets of gates. Each gate needs an 2 inbound (turboprop/jet) and 2 outbound points, all 5 miles apart. Now, join up each of those 12 points points with 4 rwy thresholds, keeping lateral separation or vertical with height requirements for crossovers. I thought it was easy too, until I tried it.

[Icarus2001]

Interesting points Nautilus Blue. A good way to view the issue.

However...There is a limit to how many 5 mile circles 1000 feet high that you can put into a given volume of airspace.

Surely the fact that these circles (cylinders?) are moving AWAY from the airport at 150-250 knots helps a great deal?

Perth seems to make life difficult. Understood they are dealing mostly with 150 degrees of departure angle but there are similar airports elsewhere in the world that process more. I know Pearce is major issue but all capital cities have constraints.

[ozineurope]

Surely the fact that these circles (cylinders?) are moving AWAY from the airport at 150-250 knots helps a great deal?

Unfortunately that only helps the one sector. As the circles move they become someone else's problem, so each sector works the capacity that it can. TWR can throw more at the TMA than they can handle, who in turn can throw more at ENR than they can handle. So the departure rate and capacity is set by the receiving sectors and when a lot of destiantions are off radar coverage, below ADSB coverage that necessarily means that the last bloke who can see them must have enough room/time to arrange them in a pleasing and eye catching manner for the final bit.

Defining sector capacity is a black art, in Europe we have the CTFM (Central FLow) whose job it is to blend and sequence all the aircraft trails so that aircraft arrive at the correct point in space and the correct time. With balnket radar coverage this still does not allow unfettered access to the airspace due to the volume of traffic. Example - BA travelling FRA-LHR has a slot departure time FRA which is designed to help it meet its slot arrival time at LHR. However due to bad winds, slight delays in loading etc they end up missing the DEP/ARR. End result they go round in circles at one of LHRs bed posts. And this is what happens after 20 years of experience.

Perth traffic has exploded - unforecast growth so that movements are now at 2020 levels. This traffic is being handled by the same number of control positions that were there in 1999. Very similar airspace (the Pearce areas have not diminished significantly since then) and less controllers are there than in 1999. So Perth operates with an APP, DEP, RAS and FLOW (who can only 'see' aircraft at about 160nm), these guys hand them off to one of 3 ML based ENR sectors. These numbers have not changed and nor has the TMA sectorisation since 1999.

Whilst Perth ATC may seem to make it difficult I would suggest that planning 70 departures between 0530 and 0700 is not the smartest piece of airline strategy ever. If you are in the first bunch and happen to be 15th to taxy your delay is automatically 20 minutes due to runway capacity. Add a heavy or 2 and this may blow out to 30 minutes, simply due to the number of aircraft not ATC, not procedures.

Now if you had 2 departure runways this delay would be transferred to when you are airborne due to sector capacity. Because you need to be separated by the 5nm/1000ft that NB spoke about. Be great for the TMA and the TWR, off frequency quickly!! But then the ENR guy/girl has to blend this mix, cause guess what they all want to exit radar coverage close to each other. So do we make you wait on the ground or give you an ENR hold or a track stretch? Bear in mind that at about the time you are getting to 200nm the other guys are starting back so we need to have lateral/vertical between the outbound trail and the inbound.

There is a lot more that can be done, but the present structure and design does not allow Perth the freedom to process more than they are unfortunately.