Looking at all the discussion that has taken place on this forum over the years about Airspace Reform, one could be forgiven for thinking we have a congested en route airspace environment that is slowing down the amount of aircraft we can move and incurring delays and added fuel burn on all users.
I have always regarded this curiously as I don't see it that way - never have.
Surely we are in this regard no different than busy envronments like the US where the limiting capacity restraint is Concrete on the ground.
So why all the focus is on these enroute long range flow schemes when what may help more is money spent on the surface infrastrucure [runways, rapid exits, full length taxiiways] (privatised airports dont help in this regard) and the same sort of speed control used in US/EU to allow closer sequencing down final approach. Profile speed control used to work reasonably well until it was all but totally abandoned about 5-6 years ago in Australia.
Have a look at this speed control system (India):
250 kts below 10,000 feet 220 kts between 30 nm and 15 nm from VOR/NDB Cat 'C' (e.g) : - 170 kts within 15 nm excluding final approach track 150 kts 10nm to 4nm on final approach track.
This is similar but generally less restricitve to some I have researched in EU.
What this allows for is more aircraft spaced closer together, and importantly more consistently spaced on final, increasing the runway utilisation. Add in making the approaches all radar vectored on to final rather than pilot interpreted and the spacing reduces further (trust me on this one!).
I just wonder why we are not doing this type of thing more rather than arguing about Class E vs Class C and D.
With the "green" drive to reduce emissions, those speeds would involve extending flap significantly earlier than the current operation and then driving t the aircraft in under power - thus increasing the fuel burn. The 150Kt from 10NM would be very expensive for larger jets - the aircraft would be in final configuration (ie gear down/flap 30) which is a huge increase in drag, thrust and fuel burn (not to mention a similar increase in noise for residential areas adjacent to airports). Even the 170 Kts requires flap 10 which is more drag than the ideal. I suggest having a look at the way the controllers in London manage the sequencing whilst allowing the aircraft to do a Continuous Descent Approach (CDA) which basically means no level flight segments by the aircraft (below 5000') resulting in reduced fuel burn and noise (all aircraft are monitored for compliance).
While you've got me thinking about the subject, I've got to say that MAESTRO SUCKS. It appears to be making huge errors in allocating the sequence of aircraft. The only way that it is ever going to work properly is if the software engineers sit down with the ATCO's and experienced pilots and redesign the factors that the software is looking for.
If ATC is serious about reducing fuel burn, then the reduction from descent speed to 250 knots must be accomplished below the "hard" altitudes stated on the STARs (ie the 9000' requirement into YSSY). I've given details about this before on this forum but if you want me to give you more info just PM me. GB
The "open stars" project for SYD (commencing Jun 08) has taken a look at techniques at LHR, which basically require most accurate track miles - updated frequently - after departing the stack. Note key word there: STACK. Maestro has many many faults (primarily TMA gates too far from the circuit, and descent speeds being too varied and unpredictable) but at least the STACK is a last resort, with delays absorbed first during circuit, then descent, then cruise (ALOFT then projecting even further back), before holding patterns are used. CDAs are nice but really not much point after 30 minutes doing circles at low level. Noise friendly, agreed. The 9000' push-down at SYD isn't ideal, but given a typical 35NM it isn't too far off optimum (except from the N). Any higher and airport capacity is increasingly impaired and/or departures are grossly penalised (think MARUB departure times three). Often we need to give you 30NM or less from TAMMI so it's no good if you're at FL130 doing 300KTS, you fu*k the sequence. There are safety difficulties from a traffic management perspective lowering the slow-down point on a default basis. There is rarely a problem asking APP for high speed to 9000 or lower if it really helps. Better that than smacking into a departure at 10000.
Ivasrus, thanks for your post. Wrt SYD, would the ATC timing be adversely affected if the STARs were amended to 250 knots by 8500'. Thinking of the worst case (Boree STAR for runway 34L/R), it makes sense to descend at normal descent speed to 9000' at Berow and then reduce to 250 knots. This way, energy is conserved until after the 9000' requirement has been met and as there is approximately 25NM to travel before the aircraft can be cleared below 6000' this energy is useful to reduce the fuel burn. Currently, we are dumping the kinetic energy prior to 10,000' and then having to put on thrust as soon as the aircraft reaches 9000'.
I agree with
Quote:
CDAs are nice but really not much point after 30 minutes doing circles at low level. Noise friendly, agreed.
but CDAs allow us to finesse the approach by keeping the aircraft in a low drag configuration until late in the approach thus saving a few hundred kilos of fuel and being noise friendly to the neighbouring community.
Of course, the biggest improvement in operating in/out of Sydney would be to get the political limitations removed and allow the experienced staff to develop procedures that really do work. GB
Appreciate and agree totally with the concept of the CDA - but if it slows up and adds extra miles to the following traffic that can not (or will not) emulate the same, is it working in the cost saving / emissions saving sense to any real 'global' (in the systemic/network sense) benefit?
Will certainly look at the EGLL technique for my own info (sounds like SY is already doing that from what has been posted above) - one good point already being made - any holding patterns / stacks need to be close in - not the 50 nm inbound fix with 70nm to run we tend to currently have. You also need accurate holding pattern time management, which is currently difficult because typically the controller performing this task now has large sectors with other competing tasks compared to an inner/arrivals controller in the sense of what occurs in EU - i.e. someone solely focussed on managing the holds precisely without too much distraction. This of course is a staffing resource problem as well - one that is probably here for a while yet.
The comments about MAESTRO are not new. You will possibly find it difficult finding someone rushing to it's defence who has to use it. If it, or it's replacement, could obtain dynamic real time winds from aircraft ACARS uploads it would make a huge difference - but from what I can gather, other company/fleet aircraft don't seem to be able to share this data either - often aircraft given slowdowns to 'cross X at' say that they can not even get there by that time by speeding up, even though the real time radar data shows they will be there 1-2 minutes ahead of what ATC need - this suggests some 'stale' wind data. (?)
The two best examples of CDA's I've experienced to date are at EGKK (Gatwick) and EGCC (Manchester). Both places have speed restrictions beyond an initial arrival fix of 250kts, and then progressively reduce this to 220-230kts, then 180 kts on a base leg for a vectored ILS, before asking you to maintain a minimum of 160kts to 4 DME. All this is carried out from the initial approach fix at around FL130, and predicated on a 3% descent gradient, so at 250kts..your ROD should be around 1250fpm etc. The London/Manchester TMA, & Director (approach) controllers are VERY good at this, and get flow rates that put SYD and BNE to shame in a more complex environment. They get this done because the infrastructure and process are in place..something that needs to happen before you can get any proper results. EGLL is a rather poor example IMHO, simply because the holds at Ockham and Lambourne are normally chocka block to accomodate the flow rates, which means the CDA is only required below FL60. EGLL could quite easily have a CDA system from FL130..if there was physically more airspace! a problem JFK, LGA, and EWR also suffer from.
In my experience, the CDA ticks all the boxes..as long as you have the airspace to do it...and it is combined with a runway slot system. My company are saving around 300kg of fuel on the 767-300 per inbound sector, compared to the old dive and drive system.
The max flow rate at Sydney of 48 - 50 is well above the EGLL acceptance rate.
I doubt very very much that SYD airport/airspace could operate at anything like that in its present form for more than an hour or twoat a time, were as EGLL operates within 2-3% of its limit for 19 hours of the day.
Mixed mode, well I'll believe it when I see it...as every fringe group, environmental facist and Black Lesbian disabled single mothers' socialist collective are opposed to it..as well as the 3rd runway
48/hr is indefinitely sustainable at SYD. However that rate clears the morning arrivals peak inside 2 hours; the traffic just isn't there to continue beyond. The current airspace could take up to 60/hr with a flowed departure arrangement and reduced arrival gaps. 48/hr to 34L+R allows for a very generous 5-6NM average spacing. THAT'S why LHR wants mixed mode.
A bit of a thread drift, but in answer to the previous post:
Not being SY based I would defer to Ivasrus who would probably be more in the loop on this one, but I think without the artificial limitations of LTOP, the 48 Rate is easily achieveable at YSSY with 2 runways available (effectviely mixed mode OPS) isn't it?
From memory, they had a 'please explain' from the (previous) government when it was exceeded! -------------------------------- EDIT: Oops - was being answered whilst I was posting!
EGLL can sustain arrivals of 45 per hour on the arrival runway, it drops if Low Wx. procedure is in operation. Combine the arrival and departure flow rates at peak, and it is about 100 per hour----but anything more than 43 per hour per runway is pushing it, and you need what YSSY hasn't got, multiple genuine high speed exits and entries.
To suggest that any kind of airspace congestion in Australia is a problem suggest to me you are smoking funny cigarettes. All the real figures are easily available ---- don't accept the ASA spin.
I most certainly endorse the view that AU ATC is set up for the convenience of ASA, not their customers ---- for over 20 years we have had the airborne capability for " four dimensional" low fuel burn (equals low noise) approaches ----much talk over the years ---- and sod all results.
It is over twenty years since we demonstrated the ability (YBBN) to meet a nominated touchdown time ---- wheels on --- consistently +/-20 sec.---- all based on aircraft equipment, long before TAAATS ---haven't we made great progress.
Given YSSY traffic mix (critical) and using all runways, up to 130 per hour is possible ---but politics and ASA almost certainly preclude such an option. If SACL has their way, and force Regionals out (to maximize revenue --- wide bodies pay a lot mote than a Saab 340) you will be back to about 70 per hour.
Whatever traffic flow the runways are capable of supporting, I doubt that the taxiways and aprons would keep up. There a just too many bottle necks.
When Jetstar push back from bays 49 to 59, all traffic southbound on taxiway C are affected. Whenever a Qantas Domestic flight pushes back from Bay 2 to 10, every other bay inside it is boxed in. For example a push back from bay 10 precludes an arriving flight from accessing Bays 1 to 9.. That is just two examples.
Regarding STARS and general airspace efficiency in Sydney can someone answer a few questions for me.
Why is it that when RWY 34L and 34R are being used for departures and arrivals, flights inbound from the north via the BOREE arrival to RWY 34R are made to descend to 9000 ft by BEROW (20 DME) and then made to drag it in for another 50 to 60 track miles. Not only that, they are cleared to descend to 6000 ft while traffic departing via 34R ENTRA departure are forced to level off at 5000 ft. Why do these crossing altitudes have to be so low? This crossing of paths happens around the Sydney harbour where the inbound traffic still has some 30 nm to run so should ideally be somewhere around 10,000 ft, and the outbound traffic would certainly prefer a clearance to 9,000 ft rather than 5000 ft.
And when inbound via the RIVET arrival for runway 34L it is OK to be cleared from somewhere between RIVET and TAMMI (42 - 20 DME) straight to a 10 mile final on a Sunday afternoon but not on a weekday. The profile after following the RIVET star matches an idle descent beautifully, and we hardly fly over any built up area. It's both minimises noise and fuel burn. But during the week we are tracked to a position 10 nm short of the airport and then turned away more than 90 degrees to then track at around another 25 to 30 nm. That's just stupid.
Firstly you should know we have the technology to make good a certain place at a certain time. Then if there is any fine tuning to be made from 30 DME why not simply give us (in the case of arrivals from RIVET to 34L a heading which will give us a base leg at various distances from the runway. If you want to speed us up, give us a vector for an 8 nm final, or if you need more spacing give us a vector for a 12 nm final. Tell us what your intentions are and we can program the required final approach into the FMC and work out how our profile is going. Perhaps you could confirm with us too what final approach leg you intend to give us and resulting track miles to run so that we can work out how we are going.
Of course these ideas are probably not new and coming from a pilot perhaps conflicts with other issues behind the scene, but that is the point of this thread, to facilitate communication between the various stake holders so that each one has a better understanding of the others.
The requirements on the STARS are to allow departures to cross above the inbounds. The alternative is to be under the inbound stream which is where the props are. eg Noise abatement requires INT departing to EAST of 34L to track NW then through A100 turn to E crossing within 20 NM YSSY.
Same via RIVET with a 16R jet departing via KAT, need to be above A100 before crossing the arrival stream.
Direct tracking to final is available only when there are no departures in / or pending for that airspace. eg props off 34L to the south.
Re: Time and space FMC 4D etc. All ATS providers are aware of the capabilities however its not there yet for a myriad of reasons. Nor despite some other posts is it used other than experimentally at any Class A airport.
For example it has been used at Schipol for a number of years in conjunction with semi CDA approaches during curfew / late night ops. The restriction is that it will only work at an acceptance rate of 15 per hour.
Track miles should be provided and updated particularly for a circling approach, if not ask.
What I would suggest is that you come and visit. We get very few pilots who actually come and chat and look at the operation. You will definitely get something out of it and so will we.
Just ask on the SMC frequency or contact the TCU useing the ERSA phone number, we go out of our way to accomodate all such requests.
Last edited by Davanian : 15th March 2008 at 01:26.
From first principles it would seem that you get better utilisation of the most expensive assets (aircraft, runway, airports, drivers) by allowing traffic to flow at best possible, i.e. fastest sensible speed.
Slowing everyone down to allow them to be bunched closer together is the same kind of thinking that gets us the roads and public transport systems 'enjoyed' by most major city dwellers today.
It's not the air that's overcrowded. It's the ground. We don't need to push aircraft closer together and in doing so slow them down.
Better to figure ways to get them off the blacktop faster once they've landed, and solve the ground congestion problems.
Faster speeds and steeper profiles seem to be vastly more fuel-efficient. And fuel is another thing we are likely to be short of...
Anyone say RyanAir? Those blokes know how to run everything down to the last decimal place on costs, and I don't think they'd welcome the idea of slowing down to touchdown speeds 10nm off the threshold.
With all due respect to ATC on the sub-continent, I'd rather look at the Berlin Airlift model for ideas on how to handle more traffic in less space AND TIME than the Indian model. (58+arrivals per hour at Gatow and similar at Templehof, as I recall).
BN App, you are looking at it all from the wrong angle. The airlines generally seem to think the airspace structure is OK and they are the ones where procedures like the Indian example you outlined above would benefit. The E and NAS stuff is argued by (mostly) the people who don't use the major airports but want their 'freedoms' to fly their bug smashers how and where they please. The two groups are almost totally exclusive of one another.
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