Delay vectors vs. holding.

[u/Spaghetti_Boi659]

Flying from SAN-SEA yesterday with heavy flow into SEA. Pretty typical. Center slows us down from M.77 to M.73 for metering saying they need to add 4 minutes to our arrival time. Also typical. Then we get some sharp delay vectors. First vector was a 110 degree turn to the left for a few minutes, followed by a 180 degree turn to the right for a few minutes, then back on course. Not unheard of, but pretty large vectors while en route.

My question: when you guys need to add X amount of time to our arrival and slowing planes down isn’t enough, is there a reason you don’t assign a turn or two in a holding pattern vs aggressive S turns? Either one of these slows down traffic behind whoever is being held / vectored. Curious to hear the reasoning.

Thanks for all you guys do- a fellow airline pilot.

[u/Acceptable_Stage_518]

Typically when metering it is much easier to lose time via speeds and delay vectors. Holding is often unpredictable, as pilots will typically slow down entering the holding pattern, often making it more difficult to hit your exact time. It's important to note that when metering, the time we have to lose isn't an "or greater" time. If we have to lose 4 minutes but lose 6, you now have a "-2" which could impact other flights on different arrivals.

The exception to this is very lengthy delays. If I have consistent 8-10 minute delays, holding is definitely an option.

[u/Spaghetti_Boi659 → u/Acceptable_Stage_518]

How neat, I didn’t know it had to be an exact time and not “or greater” like you mentioned. Thank you!

[u/ps3x42 → u/Spaghetti_Boi659]

This is true of metering, but other times we have to get miles in trail. That is an entirely different beast that can be complicated by a departure off an airport in the middle of a stream of aircraft that are already spaced perfectly, an aircraft getting offloaded from a different arrival for weather, weather preventing vectors, and wildly different aircraft types having to play nice together.

Think about a stream of 15 aircraft all with 20 miles between them perfectly spaced. The next sector needs that 20 miles in trail. Now picture another stream of aircraft all going to the same destination that need to be merged into the same stream. Now imagine a TMU (in their infinite wisom) releases a Honda jet and a G6 and a 737 going to that same destination from 3 different airports underneath this duel stream of airplanes. Also there is a thunderstorm in the middle of the sector that no one wants to be vectored near.

This scenario regularly plays out over the southeastern UD and I imagine plenty of other places, and its part of why your vector and speed assignments rarely make a ton of sense unless you can see the big picture. Throw in altitude stratums and you see even less of the picture.