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STCA alert generation

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STCA alert generation

Old 10th Aug 2015, 13:29
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STCA alert generation

According my limited knowledge about STCA (short term conflict alert) it generates a warning between 45 and 60 seconds ahead of a potential conflict.
Here's my question:
Is the lead time for a warning identical for a conflict closing in at 200kts or a conflict with identical geometry but the tagets at 300kts?

I would assume so, but I need a firm answer from a professional.

Thanks
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Old 10th Aug 2015, 21:05
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On which kit?
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Old 10th Aug 2015, 21:39
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I doubt if there's any fixed limit. There might be some ICAO/EASA guidelines, but with every single ATM system and ATC provider it might get a little different. In general STCA warning is time-based, so faster closing aircraft generate it within larger distance. STCA alert is usually distance-based and it gets triggered when the separation is already lost.
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Old 11th Aug 2015, 00:51
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Ours goes off before separation is already lost, time based, as in they go off a given time before separation will drop below a set minimum. I always though this was the norm

Last edited by Una Due Tfc; 11th Aug 2015 at 01:13.
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Old 11th Aug 2015, 09:27
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I always though this was the norm
No, depends on how it is perceived.
In some respects its a bit like a goalie so you still have time to prevent an incident.
In others once it goes off regardless of what actions taken by an ATCO prior to activation its deemed to be a loss even if separation standards are maintained.
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Old 11th Aug 2015, 11:58
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Thanks for the replies so far. It appears that there's no quick and easy answer, like in so many things in aviation.

Let's assume two targets on an exact opposite course at the same altitude. Both straight and level, no manouvers whatsoever. In the first case they both travel at 200kts, in the second case they both travel at 300kts. Would it be safe to assume that the TIME before conflict of a STCA alert would be identical (and therefore the distance between the targets at the moment of the alert is different)?
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Old 11th Aug 2015, 19:30
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NODE L used to (if I remember correctly) start with a line and flash at 20 miles, go Amber at 10 then red at 5. It's been a while though!
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Old 21st Aug 2015, 17:45
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Should still have something similar to thisUntitled Document which is for MTCA but can't find it anywhere. All my old training docs. are now in a museum but found this quote
February 1980
The Short-Term Conflict Alert (STCA) tool becomes available. The system provides controllers with a pre-warning of 128 seconds about possible infringements of minimum separation standards.
Times change, you might find more on page 3 of www.skybrary.aero/bookshelf/books/299.pdf this

Last edited by Lon More; 21st Aug 2015 at 17:59.
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Old 22nd Aug 2015, 02:01
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It'll change depending on country/system/airspace. I know with the one I've worked on most recently it's purely time based. But that was sector specific, not even country-wide.
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