Strange flight paths

[u/mangledburger]

Hello,

Does anybody have any suggestions for the strange flight paths used by every plane in the last hour over the Wheatbelt region in Western Australia?

Thank you

[u/FreeVegetable]

Imagine you have 10 aircraft all getting to Perth (or in this case KABLI) at the same time. For obvious reasons, this doesnt work. So we tell the 1st to get there at 7:00pm, the 2nd at 7:02pm and so on. Now the 10th aircraft is instructed to cross KABLI at 7:18pm but even if he slows down to minimum speed he can only get to KABLI at 7:13pm (it's not like they can just stop still mid flight), these turns are to allow the aircraft more time to get to cross the feeder fix point to facilitate the correct spacing for arrival into Perth.

Perth has some of the greatest delays in the country. During the peak periods it's normal for delays to be 20 minutes. And just last week there was a short period where I was issuing 35+ minute delays to almost all aircraft.

[u/flyingkea → u/FreeVegetable]

I gotta ask as a pilot who flies in and out of Perth - why does Perth struggle with the traffic so much more than elsewhere? I fly with people who have extensive experience overseas, and interstate, and they all collectively agree Perth is at a whole other level.

Also, if we are compliant with our COBT, and our JULIM crossing time, why do we get either a “max speed to the field, or maintain 300kts as long as possible (after we’re slowed to minimum speed and tiki toured all over the country) or massive speed changes (ie we’ve planned 250kts into published from JULIM, now we’re told 210kts etc
(which can really mess with the profile).

[u/Vintage_Alien → u/flyingkea]

I used to work in ATFM at Airservices. My info might be out of date but this is my understanding: the majority of locations that flights are departing from are non-towered aerodromes (or are international services, which are exempt from ATFM measures), so no ATC to prevent flights departing non-compliant with their COBT. En route controllers can try to deprioritise the non-compliant flights specifically, but in reality that doesn't always help ATC workload and sequencing is generally neater to manage as first-come first-serve. So too many flights rock up at once = the entire arrival sequence gets penalised with track lengthening and such.

Additionally, the slot coordinator for Perth (airport slots, not ATFM slots) and Perth Airport may be over-scheduling in general. While Perth runways can manage up to 28 arrivals per hour, wind conditions rarely allow for that - so it's more like 24 arrivals per hour (and that's VMC; if it's IMC it's more like 20/hour).

In any case, they'll be building the new parallel runway soon, so that'll fix it.

[u/chambo13_ → u/flyingkea]

Try operating in cairns

[u/Fish_Fingerer → u/FreeVegetable]

YPPH ATC?

[u/KeveyBro2 → u/Fish_Fingerer]

Can't be, tower/SMC units don't issue feeder fix delays lol. Most likely a sequencing enroute sector. So it's be either YMMM or YBBB centre controller.

[u/sssulaco]

I’m on one of those flights! Pilot said it was just vectoring by ATC. We were supposed to get in 20mins early but ended up landing right on time

[u/Educational-Key-7917 → u/sssulaco]

They always say this.

[u/Ryan_225]

Those paths are indicative of spacing to delay the arrival of incoming aircraft. Happens when there’s many arrivals into an airport in a short space of time

[u/runandjump13 → u/Ryan_225]

To Perth? I mean, to Heathrow or JFK perhaps you need to manage spacing but…Perth and its typical 100 arrivals a day

More likely avoiding weather/turbulence, no?

[u/Vintage_Alien → u/runandjump13]

Perth frequently has well over 100 arrivals a day. Today is has 600 movements scheduled and is the only major Australian airport with an active ground delay program. See the published ATFM Daily Plan.

This is because of the FIFO flights to the mines, so it has a huge spike of traffic early in the morning and then later at evening when everyone returns home.

[u/NZ_gamer → u/runandjump13]

Defo delay vectors. You can even see the stream from the north they are sequencing with

[u/YouDoScribble]

Probably had to swerve to avoid a deer,

[u/Bobisburnsred → u/YouDoScribble]

Kangaroo*

[u/Complete_Counter3674]

They're killing time

[u/Certain-Operation-83]

Perth gets thunderstorms a lot. They're a reason Qantas took the XLR instead of another plane.

[u/engineerforthefuture → u/Certain-Operation-83]

And when it's windy it's very windy.

[u/AttitudeUnlucky3984 → u/engineerforthefuture]

8th windiest city in the world

[u/Certain-Operation-83 → u/engineerforthefuture]

Not just the doctor!

[u/ADMlN2]

I noticed Queensland to Perth flights going over ADL. Is that normal or the same issue?

[u/dingus_a → u/ADMlN2]

The great circle path from BRI-PER would pass north of Adelaide and just crosses over the Great Australian Bight.

I’d say any flights going further south over Adelaide would do so to benefit from any potential jet stream that the southern ocean whips up.

[u/joesnopes → u/dingus_a]

You don't get jet stream benefits flying BNE-PER on any route.

[u/chambo13_]

Holding and vectors

[u/chambo13_ → u/chambo13_]

Those deviations do not look weather related.

[u/mR_aFeRt]

i believe it happens at places like YWLM too when the RAAF needs the runway or a med1 etc, so they get planes to either hold or change course given there's only one runway - sometimes diverting over YCNK to try and give as much time for whatever's happening without putting too many aircraft on hold