The concern related to the confusion caused by an operator using similar call signs for flights operating at similar times.
The reporter expressed a safety concern regarding the confusions arising from the similarity of flight numbers in use by the operator.
The reporter advised that [callsign 1] and [callsign 2] operate in the same area with both flying to Brisbane. The reporter advised that recently both aircraft came onto frequency within about five seconds of each other. The controller issued a clearance to the wrong aircraft but the error was recognised immediately by the other flight crew and corrected.
The reporter is concerned that two aircraft can be operating in the same airspace with such close flight number call signs.
[Call sign 1] is a [location 1] to Brisbane flight with an estimated time of departure of 0630 UTC and an estimated time of arrival of 0730 UTC. Which is occasionally upgraded to a [aircraft type] service, this services has been operated for over 18 months.
[Call sign 2] is a [location 2] to Brisbane flight with an estimated time of departure of 0550 UTC and an estimated time of arrival of 0725 UTC. This service has existed since we began this sector.
We are only aware of one reported instance of call-sign confusion for this combination. Notwithstanding the low occurrence rate, we acknowledge that this arrangement represents a conflict and have renumbered [call sign 2] to be effective on [date].
We continue to explore options to reduce the risk of call sign confusion both tactically and in the scheduling phase.
CASA has reviewed the REPCON and notes the corrective action from the airline. CASA also notes that this REPCON and others recently reviewed appear to have been submitted by air traffic
controllers. If so, the reporter should be encouraged to submit a report in the Airservices incident reporting system. This topic will be placed on the agenda for the next CASA quarterly meeting with Airservices.
Readers are also referred to REPCON AR201500050 and AR201500061 for REPCONs which also relate to this issue.