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I have seen reference to ATC assigned "arrival gates".

As a passenger, an "arrival gate" is something like B12 or D37, but I'm quite certain that's not what this is referring to.

From an ATC perspective, what is a flight's "arrival gate"?

60levelchange
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FreeMan
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2 Answers2

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Different ATC facilities need a standardized way to manage handoff of traffic between them and make sure traffic headed in different directions doesn't conflict at the border, especially at the interface between Approach/Departure and Center where traffic is climbing or descending and therefore can't be separated by cruise altitude like en route traffic can.

The standard way this is done in the US is to establish "gates", which are fixes/waypoints on the airspace control boundary, and each is designated for arrivals (descending) or for departures (climbing). Note that this boundary is not related to airspace class and is not charted, though you can often deduce where it is based on traffic patterns and SIDs/STARs.

Here is a conceptual diagram of the ATC gates for an airport in "south flow", meaning aircraft use the runways in the southerly direction:

Gate Diagram, South Flow

Source: here

The black crosses in the corners are the arrival gates, and the white crosses on the sides are the departure gates. When the airport is in north flow, the diagram is flipped vertically. For airports that are oriented east-west, the diagram will be rotated 90 degrees for east or west flow. Most traffic will use a runway on the same side as its arrival gate, but there are crossover paths for when Approach needs to rebalance traffic or some gates are closed due to severe weather.

When a gate is "open", there is an agreed maximum rate or minimum spacing that the sending facility can send aircraft through it, hence the term "metering fix" on the diagram legend. If the sending facility exceeds this rate, the receiving facility may "close the gate" until they can sort out the resulting mess, which means the sending facility will have to slow down, reroute or hold traffic until the gate reopens. Nobody wants that.

StephenS
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  • I'm not sure "metering fix" is the same thing as "approach gate". The FAA's definition says that an approach gate is located on the final approach course and one mile outside the FAF, which doesn't seem to match your diagram. Having said that, I'm sure ATC does use certain fixes further from the airport to manage inbound aircraft before directing them to intercept final outside a specific gate. Similar function but different distance from the airport, I guess. – Pondlife Oct 05 '20 at 16:50
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    @Pondlife A STAR has an “arrival gate”; an IAP has an “approach gate”. – StephenS Oct 05 '20 at 16:57
  • I'm not sure I follow. Aircraft don't unload passengers and cargo at one gate, then get pushed to another gate for onboarding new passengers and cargo. It's done all at the same gate. Having separate departure and arrival gates doesn't seem to jive with what you see at an airport, for instance. – SnakeDoc Oct 06 '20 at 17:34
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    @SnakeDoc This has nothing to do with pax/cargo or terminals. These “gates” are fixes in the air. – StephenS Oct 06 '20 at 17:35
  • Oh I see now, the entry position into the holding pattern/final approach. I think I interpreted OP's question as being about the actual parking locations on the ground. – SnakeDoc Oct 06 '20 at 18:02
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In that context I believe it actually refers to the "approach gate". This is from the FAA Instrument Procedures Handbook, Chapter 4:

The approach gate is an imaginary point used within ATC as a basis for vectoring aircraft to the final approach course. The gate is established along the final approach course one mile from the FAF on the side away from the airport and is no closer than 5 NM from the landing threshold.
[...]
When vectoring aircraft to the final approach course, controllers are required to ensure the intercept is at least 2 NM outside the approach gate

You can get more details from the ATC side in the ATC orders 5-9-1.

Pondlife
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    In fact this does not answer the question. The question was about arrival gates, which are the handover points between Radar and Arrival. In most cases the arrival gates are also the begin of a STAR or transition – pcfreakxx Oct 09 '20 at 20:10
  • I wrote the words he was asking about, so I can assure you that it had nothing to do with approach gates. – StephenS Mar 29 '22 at 16:24