Is Aussie ATC too slow?

[MEL_Traveller]

Sixth in line for takeoff at MEL tonight. 28 minutes for 6 aircraft to take off.

Between takeoffs we had to wait for each incoming… which of course were miles away.

So we sit. And wait.

And wait.

I can’t help but compare to LHR or JFK where 28 minutes would have seen double the number of takeoffs?

Are we too cautious in Australia? Do other countries have better systems? Or are we somehow best-practice in Australia?

 

[justinbrett]

Sixth in line for takeoff at MEL tonight. 28 minutes for 6 aircraft to take off.

Between takeoffs we had to wait for each incoming… which of course were miles away.

So we sit. And wait.

And wait.

I can’t help but compare to LHR or JFK where 28 minutes would have seen double the number of takeoffs?

Are we too cautious in Australia? Do other countries have better systems? Or are we somehow best-practice in Australia?

It’s nothing to do with ATC. It’s the runways.

JFK and LAX have double parallel runways. LHR has a single set.

MEL will improve once the new runway opens.

Having a dedicated departure runway and a dedicated arrival runway (that don’t intersect) is so much more efficient than mixed. For dedicated departures, the standard is 6000FT down the runway and airborne (unless wake turbulence is required) You couldn’t launch them closer than that if you tried.

 

[MEL_Traveller]

It’s nothing to do with ATC. It’s the runways.

JFK and LAX have double parallel runways. LHR has a single set.

MEL will improve once the new runway opens.

Well, yes, dedicated runways at LHR for arrivals and departures… but planes takeoff there every 45 seconds? Why is it we wait three minutes for an inbound in AU? Could two planes have taken off in that time?

Why in SYD do we separate domestic and international, and have departures and arrivals sharing a runway? Can’t we copy Heathrow, have dedicated runways, and takeoff every 45 seconds?

It *seems* a waste of fuel, and time to be so slow. But I’m assuming there’s a good reason?

 

[justinbrett]

Well, yes, dedicated runways at LHR for arrivals and departures… but planes takeoff there every 45 seconds? Why is it we wait three minutes for an inbound in AU? Could two planes have taken off in that time?

The stats say take off OR landing every 45 seconds. x 2 runways = per runway, one move every 90 seconds (40 per hour).

Why is it we wait three minutes for an inbound in AU? Could two planes have taken off in that time?

If operating mixed departures & arrivals to the same runway, the most common way to do it is like a zipper merge - one lands, one takes off, one lands, one takes off. This requires approach to have a big enough gap between arrivals to get one away, but sometimes it gets tight and you can't get the departure away, which leads to further delays.

It's not a time standard, it's a number of factors. Sydney is capped at 80 moves per hour - usually over two runways which is 40 moves per runway, same as LHR. Fun fact, that's why crosswind causes cancellations because if they need to use 07/25 they can't get anywhere near 80 moves an hour.

So if all goes well - 1 take off, 1 landing = 180 seconds - 3 minutes between departures, but that's best case scenario.

I can't begin to tell you how much better it is to have dedicated runways.

Why in SYD do we separate domestic and international, and have departures and arrivals sharing a runway? Can’t we copy Heathrow, have dedicated runways, and takeoff every 45 seconds?

SYD doesn't separate based on domestic and international. SYD has a terrible runway configuration and the runways are too close to reap the full benefits of parallel runways. Runway 16L/34R isn't long enough for a lot of widebodies so you couldn't use as dedicated runways - not to mention the pain it would be to taxi from the international terminal to 16L/34R.

It *seems* a waste of fuel, and time to be so slow. But I’m assuming there’s a good reason?

Fuel burn at idle is pretty minimal. Better a delay on the ground than a delay in the air.

 

[MEL_Traveller]

Thanks! Appreciate the time taken to answer. Not sure it makes me feel any better.

I guess it’s the zippered approach that I can’t get my head around… why so long between departures and arrivals? Is ATC getting it wrong and being over cautious? Or are they exhibiting best practice? Or could they ‘zipper’ them better?

JFK peak times it seems a line of aircraft waiting to takeoff, and they expertly manoeuvre them between arrivals. You don’t seem to have the luxury or three minutes between landings in JFK?

Or is it just perception? (that it takes so long?)

Just in the SYD runway use… i notice 737s arriving from NZ (for example) use the ‘international’ runway, while domestic get the runway on the far right. Couldn’t they slot those 737s to the domestic side to free up space?

 

[justinbrett]

Thanks! Appreciate the time taken to answer. Not sure it makes me feel any better.

I guess it’s the zippered approach that I can’t get my head around… why so long between departures and arrivals? Is ATC getting it wrong and being over cautious? Or are they exhibiting best practice? Or could they ‘zipper’ them better?

JFK peak times it seems a line of aircraft waiting to takeoff, and they expertly manoeuvre them between arrivals. You don’t seem to have the luxury or three minutes between landings in JFK?

Or is it just perception? (that it takes so long?)

First I do think it is in your head that JFK is that much quicker, as they are capped at 81 moves per hour, only 1 more than SYD.

Assuming we are talking about 737s, you can't really depart an aircraft once the arrival aircraft is within 5 nautical miles. The departure has to be up and away before the landing aircraft crosses the threshold.

You have to add up the time of the landing aircraft completing its roll, the take off clearance being issued, the aircraft complying with that clearance (noting they are not required to roll immediately), then that aircraft conducting its take off roll.

It really depends on the aircraft and the pilots on the day, how much ATC want to push it - 3 minutes would be playing it fairly safe, I'd say the minimum would be 2 minutes.

5NM at 140KT = 2.3 minutes, so that checks out.

That's really oversimplifying it, but it would make a lot more sense if you saw it from the tower.

Just in the SYD runway use… i notice 737s arriving from NZ (for example) use the ‘international’ runway, while domestic get the runway on the far right. Couldn’t they slot those 737s to the domestic side to free up space?

Plenty of domestic use 16R/34L (in fact 16R is excellent for QF departures, it's right next to the apron)

Internationals do use 16L/34R, just not as often. It's a massive pain to taxi from the international terminal to 16L/34R as it requires crossing 16R/34L.

It's also not just the taxi considerations, there are Standard Instrument Departures that are runway specific (which are designed for efficient traffic flow in the air) - so the flight plan might determine which runway is used.

ATC isn't simple. I've oversimplified here but hopefully that's the basic picture covered.

 

[AustraliaPoochie]

SYD KSA has got dual runway ops, and its amazing to watch the parallel takeoff and landings, I don't mean the EW but meaning 16L and 16R/34L and 34R.

 

[MEL_Traveller]

First I do think it is in your head that JFK is that much quicker, as they are capped at 81 moves per hour, only 1 more than SYD.

Assuming we are talking about 737s, you can't really depart an aircraft once the arrival aircraft is within 5 nautical miles. The departure has to be up and away before the landing aircraft crosses the threshold.

You have to add up the time of the landing aircraft completing its roll, the take off clearance being issued, the aircraft complying with that clearance (noting they are not required to roll immediately), then that aircraft conducting its take off roll.

It really depends on the aircraft and the pilots on the day, how much ATC want to push it - 3 minutes would be playing it fairly safe, I'd say the minimum would be 2 minutes.

5NM at 140KT = 2.3 minutes, so that checks out.

That's really oversimplifying it, but it would make a lot more sense if you saw it from the tower.



Plenty of domestic use 16R/34L (in fact 16R is excellent for QF departures, it's right next to the apron)

Internationals do use 16L/34R, just not as often. It's a massive pain to taxi from the international terminal to 16L/34R as it requires crossing 16R/34L.

It's also not just the taxi considerations, there are Standard Instrument Departures that are runway specific (which are designed for efficient traffic flow in the air) - so the flight plan might determine which runway is used.

ATC isn't simple. I've oversimplified here but hopefully that's the basic picture covered.

Really appreciate the answers!

I guess it just feels a lot longer… like they say, every minute you are on hold feels like 6 minutes! Tonight we pushed back bang on time at 7, but weren’t airborne until 734. And we were number six in line per FR24… which is where i was looking at the gaps between the arriving and departing aircraft.

 

[jrfsp]

Lack of rapid turn offs at aussie airports don’t help either.
The main runway at MEL has a single rapid exit, compare that to other majors around the world, makes a difference over the course of an hour

 

[AustraliaPoochie]

The BNE one is good, my one flight, AKL - BNE a few years back now, landed it seems very fast, then made a turn for the BNE int terminal near where the circular fuel tanks are.
It was a landing over North Stradbroke, but I didn't get the window seat, ((too late with OLCI, so lost the window seat I had booked with, got a middle D seat still in J class tho)).

 

[jb747]

I’m not sure that rapid taxiway exits help all that much given the airport configurations that we have. Whilst in theory you can enter them at up to 50 knots, some, like Sydney 16R, end in very tight turns that can only be done at slow speeds. Basically you’re simply giving yourself a massive braking problem. Aircraft essentially make very bad cars, and not getting the speed under control for any turns will result in under steering into the boonies.

The thing that I missed most, and which is used in many places around the world, is the conditional line up clearance. If I recall correctly it was used by some Australian airports, but not others, which implied that the ATC was working to different rules across the country (but I may be wrong about that). The conditional clearance lets the aircraft crew decide when to roll after an aircraft landed in front to them. So, you could have the engines spooling up as the landing aircraft approached the fence, and roll as soon as he passed. In Melbourne (I mostly operated out of there for my last few years), you never seemed to get the clearance until the landing traffic reached his exit taxiway. That took time in itself, but it then took another 15-30 seconds before your aircraft would spool up and start to move. This was time that could be saved with a conditional clearance. Dubai was a place where they were used a lot, and given the preponderance of large, and slow to accelerate, A380s, the place wouldn‘t have worked at all otherwise.

 

[justinbrett]

I’m not sure that rapid taxiway exits help all that much given the airport configurations that we have. Whilst in theory you can enter them at up to 50 knots, some, like Sydney 16R, end in very tight turns that can only be done at slow speeds. Basically you’re simply giving yourself a massive braking problem. Aircraft essentially make very bad cars, and not getting the speed under control for any turns will result in under steering into the boonies.

The thing that I missed most, and which is used in many places around the world, is the conditional line up clearance. If I recall correctly it was used by some Australian airports, but not others, which implied that the ATC was working to different rules across the country (but I may be wrong about that). The conditional clearance lets the aircraft crew decide when to roll after an aircraft landed in front to them. So, you could have the engines spooling up as the landing aircraft approached the fence, and roll as soon as he passed. In Melbourne (I mostly operated out of there for my last few years), you never seemed to get the clearance until the landing traffic reached his exit taxiway. That took time in itself, but it then took another 15-30 seconds before your aircraft would spool up and start to move. This was time that could be saved with a conditional clearance. Dubai was a place where they were used a lot, and given the preponderance of large, and slow to accelerate, A380s, the place wouldn‘t have worked at all otherwise.

MATS has a rule that you can't use conditional clearances where there is a illuminated stop bar. I never worked at an airport with them so conditional line up clearances was my SOP - it's set and forget.

The other trick was starting the take off clearance before the landing aircraft had vacated the runway (especially if it was a lengthy LAHSO clearance) - you just had to drag it out so the words "cleared for take off" came the second the other aircraft vacated. It was a bit of an art, and sometimes if you got it wrong you had to be a bit creative in order to drag it out without breaking the transmission. I'm sure the pilots knew exactly what we were doing.

It really all depends on the controller on the day, it's embarrassing to line an aircraft up and then tell them to vacate when you messed it up, so most will issue hold short if in doubt. It then relies on the approach controller to leave a big enough gap so you can get the departure away - the worst combination is a risky approach controller with a risk adverse tower controller.

 

[justinbrett]

Lack of rapid turn offs at aussie airports don’t help either.
The main runway at MEL has a single rapid exit, compare that to other majors around the world, makes a difference over the course of an hour

I reckon it would buy you 5 seconds per cycle - 10 being generous. Where the taxiway is (high speed or not) makes more of a difference, as if they just miss a taxiway and have to taxi another 1000FT to the next one, that's an extra 10-15 seconds on the runway.

 

[AviatorInsight]

Sixth in line for takeoff at MEL tonight. 28 minutes for 6 aircraft to take off.

Between takeoffs we had to wait for each incoming… which of course were miles away.

So we sit. And wait.

And wait.

Unfortunately the weather around Melbourne last night didn't help. Aircraft in front of us wanted a good 30sec to 1min in the lined up position to "check the radar". This put us on the back foot as well with only 4 aircraft in front and took us 25mins to get airborne and we still had to go to Sydney and then come back through that to get to Perth.

Throw a go around into the mix, and it becomes messy very quickly.

The thing that I missed most, and which is used in many places around the world, is the conditional line up clearance.

Yes!! I was very sad when the stop bars literally put a stop to all that. DPS still uses it and suffix the line up clearance with "be ready immediate".

 

[MEL_Traveller]

Unfortunately the weather around Melbourne last night didn't help. Aircraft in front of us wanted a good 30sec to 1min in the lined up position to "check the radar". This put us on the back foot as well with only 4 aircraft in front and took us 25mins to get airborne and we still had to go to Sydney and then come back through that to get to Perth.

Throw a go around into the mix, and it becomes messy very quickly.


Yes!! I was very sad when the stop bars literally put a stop to all that. DPS still uses it and suffix the line up clearance with "be ready immediate".

Thanks!

I dunno why this sort of information can’t be shared with pax up front by airlines. Providing us with information about every stage of the journey, like ATC holds, would go a long way to helping pax understand delays.

 

[Quickstatus]

If speaking too slow is a thing I would rather ATC speaking a little slower than some of the ATS in the US..

 

[justinbrett]

If speaking too slow is a thing I would rather ATC speaking a little slower than some of the ATS in the US..

When the occasion calls for it you have to speak fast.

95% of what is said are standard phrases - it's a liturgy and professional controllers and pilots both know what to expect next. The system works.

If it's something other than what is expected - that's when you slow down, emphasise. If it's a foreign pilot with poor English skills, or perhaps a GA pilot, absolutely it will be slow and clear for them.

And of course, we have readbacks to ensure the message was received.

 

[Gremlin]

@justinbrett and @jb747 — thanks for the detailed explanations. I love the perspective that you offer. It gives me a whole new view on how it all works. Genuinely much appreciated!

 

[jakeseven7]

Can I just say this is the best thread on this site in a long long long long time.

Thank you to the expert contributors!

Really interesting.

 

[jb747]

In Dubai, we there were multiple line up points on the departure runways, so they were relevant to aircraft crossing the runway (which we almost always had to do on departure, and occasionally on arrival), and at the next junction would affect aircraft lining up. The upshot was that we'd often be holding right next to another aircraft. I made a point of showing the new pilots just how much delay could be incurred here, by timing aircraft next to us, from when they got their clearance to the point that the nose crossed the hold short line. There were a couple of parts to that equation. How quickly they actually spooled up, and then how far they had to move before reaching the line. My point was a) the instant you get your clearance you can start the spool up and b) if you stopped some distance before the line then it would take time to traverse. I forget the exact numbers now, but I don't think it was unheard of for a minute to elapse before they crossed the runway hold short line. Time wasted.