The title is really short and I don't know how to make it easier to understand.

I watch flightradar24 and see flights coming from SFO/OAK/SJC headed to SEA make a turn over southern Oregon then come back around, like they are avoiding something. I can't think of anything they would need to avoid. There is no military space, the tallest mountain is like 9500' and there are no storms that small there. The web site says it is 03:45 UTC.

AS2938 OAK-SEA
DL2661 LAS-SEA
AS1797 LAX-SEA
AS2234 SNA-SEA

These are four of the flights that make this turn. Southbound flights do not seem to be making this turn and flights to PDX or HIO do not seem to be making this turn. Could it be weather issues in SEA?

Those are delay vectors issued by Seattle center

N353SK wrote:

Those are delay vectors issued by Seattle center

What is the most common reason? Low visibility? Weather? I don't know about these things so I have to ask.

I also noticed some flights from the East Coast were making this type of maneuver. Not all flights. One from ORD and another from PHL were more direct. Flights from CLE and OKC made the same turns over eastern Washington.

Passing Shasta northbound Seattle center will often say... i need to lose xx minutes on your battleground vor crossing time (or hawks, landing south). Two minutes I can make my slowing. Seven or nine and we are doing delays vectors.

Could just be traffic going into KSEA, caused by weather or the inbounds all started showing up an hour out with converging arrival times, could be runway direction change, emergency in SEA terminal area. An earthquake once caused all sorts of diverts.

GF

seb146 wrote:

N353SK wrote:

Those are delay vectors issued by Seattle center

What is the most common reason? Low visibility? Weather? I don't know about these things so I have to ask.

I also noticed some flights from the East Coast were making this type of maneuver. Not all flights. One from ORD and another from PHL were more direct. Flights from CLE and OKC made the same turns over eastern Washington.

This is my subjective opinion, but generally it's just because SEA does a poor job of handling inbound traffic. I can't think of any other airport that gives severe airborne delays on a regular basis.

To put it simply, the center controller is told he has to hand you off to Seattle Approach at a specific time and if you can't slow enough to make that time in a straight line you'll wind up zig-zagging.

Regarding delay vectors, the runways can only handle a limited number of aircraft every hour. Break that down into 5 min increments and you then have airlines all scheduling their flights near the same arrival time (times that pax are purchasing those flights for) and the runways will quickly become saturated if every aircraft gets to go direct. I can almost guarantee that there are not much greater than 3nm spacing between aircraft on the SEA finals when these "delay vectors" are being issued.

I would encourage any pilots and enthusiasts to set up a tour of your local ATC facility, it's very straightforward in the US for U.S. citizens and tours are offered durning normal business hours. It will give you an entirely different perspective as to why ATC asks you to do things that may not make sense.

I can't think of any other airport that gives severe airborne delays on a regular basis.

Try Mumbai or Dubai sometime. I got a 30 minute hold followed by 45 minutes of vectoring one clear night in Mumbai. Holding at 2am is pretty normal in Dubai.


GF

atcdan wrote:

Regarding delay vectors, the runways can only handle a limited number of aircraft every hour. Break that down into 5 min increments and you then have airlines all scheduling their flights near the same arrival time (times that pax are purchasing those flights for) and the runways will quickly become saturated if every aircraft gets to go direct. I can almost guarantee that there are not much greater than 3nm spacing between aircraft on the SEA finals when these "delay vectors" are being issued.

I would encourage any pilots and enthusiasts to set up a tour of your local ATC facility, it's very straightforward in the US for U.S. citizens and tours are offered durning normal business hours. It will give you an entirely different perspective as to why ATC asks you to do things that may not make sense.

And as a retired controller I will second what atcdan wrote about visiting a facility, particularly a large TRACON or Tower. Many of my airline/corporate buddies visited me at work a number of times and they were always amazed how the system works from the inside even though they lived in the system on a daily basis. Plus, sooooooo many controllers are not pilots and have limited knowledge of what happens on the flight deck when they give some clearances. It's always a win win situation for the pilot/controller community. I wish the FAA would streamline the Flight Deck Training Program (FDT) like the old FAM Program was and not make it so difficult for controllers to utilize so more would take advantage of it again.

One thing also that may have occurred at SEA, not sure when the "Heavies" arrive into SEA, but that would put more stress on the finals when you have to apply wake turbulence separation, just a WAG.

IAHFLYR wrote:

atcdan wrote:

Regarding delay vectors, the runways can only handle a limited number of aircraft every hour. Break that down into 5 min increments and you then have airlines all scheduling their flights near the same arrival time (times that pax are purchasing those flights for) and the runways will quickly become saturated if every aircraft gets to go direct. I can almost guarantee that there are not much greater than 3nm spacing between aircraft on the SEA finals when these "delay vectors" are being issued.

I would encourage any pilots and enthusiasts to set up a tour of your local ATC facility, it's very straightforward in the US for U.S. citizens and tours are offered durning normal business hours. It will give you an entirely different perspective as to why ATC asks you to do things that may not make sense.

And as a retired controller I will second what atcdan wrote about visiting a facility, particularly a large TRACON or Tower. Many of my airline/corporate buddies visited me at work a number of times and they were always amazed how the system works from the inside even though they lived in the system on a daily basis. Plus, sooooooo many controllers are not pilots and have limited knowledge of what happens on the flight deck when they give some clearances. It's always a win win situation for the pilot/controller community. I wish the FAA would streamline the Flight Deck Training Program (FDT) like the old FAM Program was and not make it so difficult for controllers to utilize so more would take advantage of it again.

One thing also that may have occurred at SEA, not sure when the "Heavies" arrive into SEA, but that would put more stress on the finals when you have to apply wake turbulence separation, just a WAG.

Totally agree with this one, I've done a tower tour, and need to do a tracon or center tour as well for some perspective. As a pilot, I've run into controllers who have given really complex clearances, and have gotten into the habit of asking "could you give us a vector while we set that up the box?"

Regarding the delay vectors, the colloquialism for that is the "Seattle Shuffle," and I've gotten it on airline flights quite a lot. Recently there's been some runway work going on, so it's become more frequent.

GalaxyFlyer wrote:

I can't think of any other airport that gives severe airborne delays on a regular basis.

Try Mumbai or Dubai sometime. I got a 30 minute hold followed by 45 minutes of vectoring one clear night in Mumbai. Holding at 2am is pretty normal in Dubai.


GF

Moving airplanes from Dubai World to Sharjah is a few miles apart, should be a few minutes...and often takes about four hours, between the taxi ride to the airplane, getting it ready, making the flight, etc. Then again, JFK-EWR is only a few miles apart too and can easily take that amount of time.

To the original poster, routing is handled in many cases by departure procedures (SIDs) and standard terminal arrival routes (STARs), rather than simply flying a straight line. This is done for a number of reasons, but simplifies traffic flow, allows for reasonable climbs and descents, keeps aircraft away fro noise sensitive areas, integrates these routes with arrivals and departures from other airports, etc. You may be seeing some of this.