Loss of separation at FL350 near Grafton - Two E190 aircraft.
 

An interesting occurrence. Reports elsewhere say 400' was the least vertical separation reached.

https://www.atsb.gov.au/publications...rt/ao-2023-039

IF they were in TIBA or one of the TRA's is there any separation standard?

No, there would not be.

But not relevant in this incident.

Given that a controller instructed one aircraft to turn we can assume it was not TIBA.

I'm curious to know what happens in these TRA sectors - do the all the conflict alarms get turned off, screens switch off etc? I'd be surprised if there is no-one looking at them - but just not enough (qualified) people to provide the service. The airport that most recently started all of this - Darwin - clearly had some staff on duty through the nights - just not enough.

So for this incident, I wonder if it is possible someone noticed the impending problem - or an alarm went off - and that caused the instruction to go out - even though they weren't technically controlling the airspace?

As post # 3 & post #4 explained it wasn't tra/tiba so it's not relevant.

ATSB states it was "Loss of separation assurance". That is not "Loss of separation" so not sure what your other sources are talking about.

Aiservices definition: "Loss of Separation Assurance (LOSA) is when there has not been a clear application of a separation standard"
ICAO is slightly different, and in my opinon, much clearer "Loss of separation assurance: An occurrence where separation has been maintained but has not been planned, actioned or monitored appropriately.

So the incident must have involved unplanned maintenance of separation - I imagine that would be an alternative definition of TIBA!

So many questions.
AFAIK, the airspace at the time wasn't a TRA and therefore TIBA procedures were not applicable. I'm not even sure that the airspace was subject to an Operational Restriction NOTAM. But the sector grouping has had numerous TIBA/TRA and Operational Restrictions NOTAM issued over a long period of time so I think it would be fair to say that it is a Group that has been doing it pretty tough for a long period of time (too long). I feel for the Individual ATC and the Group as a whole.

Thread drift, but the question about alarms is important, especially when the APP/DEP function isn't staffed and whether other Units assuming responsibility e.g. Cairns Tower, Mackay Tower or an enroute group has the same alarms, different alarms or no alarms.

I'd say there was no "Loss of Separation" as the aircraft did not breach the standards, due to the actions of the controller in recognizing and resolving the conflict prior to that happening. I guess that is why it's a loss of "assurance" only and the investigation will be why the aircraft were put into a "potential" conflict in the first place. Both the AsA and ICAO definitions cover that.

Just to visualise this occurrence (note the map scale for both pictures by the way):
https://cimg1.ibsrv.net/gimg/pprune....945529eb0c.png

A few seconds after

https://cimg7.ibsrv.net/gimg/pprune....fd3f6d3786.png

Wonder what the workload was on the said controller at the time. Or let me rephrase, how many peoples job was the controller doing at the given time?

Reminds me of Velocity calling centre the other night. After about 5 attempts they finally got someone. The controller sounded like he was doing about 3 peoples job.