A former Chief of the Australian Defence Force (1998-2002), retired Admiral Chris Barrie, has
on the idea that China's transit
or live fire exercises in the Tasman Sea were unprecedented in their conduct or notification practices.
Notably, PLAN broadcasting on guard frequency is how the first airliner-in-transit was alerted to these exercises, passing on to ATC who established the air corridor diverting other aircraft, thence to Airservices Australia, and thence to the ADF (with an independent, slower route of notification via RNZN).
The material basis of Australia's complaint regarding PLAN's lack of prior notification of a live fire exercise in the Tasman Sea is that it occasioned the diversion of
. Notably, this count includes aircraft that were rerouted prior to departure to avoid the area, so it isn't clear how many aircraft were actually required to reroute while in the air ("several").
AFR article makes some interesting points regarding the Australian response:
Defence Department officials refused to provide airlines with coordinates of the Chinese flotilla until after live-firing resumed on Saturday despite pleas from the carriers for information that would allow them to pre-emptively avoid flying near the warships.
Industry sources, speaking on the condition of anonymity because they are not authorised to speak publicly, revealed the resistance from Defence chiefs on Saturday frustrated both the airlines and the nation’s air traffic controller, Airservices Australia, as they grappled with the safety implications of military drills in the normally tranquil Tasman Sea.
Airlines such as domestic carriers Virgin and Qantas were only given the exact coordinates when Defence Minister Richard Marles’s office stepped in and ordered the department to share the information, about 20 minutes after the Chinese flotilla had carried its second live-firing exercise on Saturday.
So with the exception of two aircraft that were warned off via PLAN broadcasts on guard frequency, the other 47 aircraft were rerouted according to an exclusion corridor established by ATC in coordination with Airservices Australia, based off verbal relay from the pilots of the first two aircraft of notification/direction broadcast by PLAN via guard frequency. Notably, Airservices Australia did not have access to the location of the PLAN ships, and I assume that PLAN would not have broadcast their exact location either.
This raises the possibility that the exclusion corridor created by ATC and Airservices Australia may have been significantly larger than was actually necessary, operating on incomplete information and out of an abundance of caution, thereby potentially affecting more flights and/or to a greater extent than was actually necessary. That Airservices Australia, Virgin and Qantas were attempting to obtain coordinates for the PLAN task force from the Defence Department suggests that they believed that information to be materially relevant to informing the routing of flights. All of which leads to the following question: if Airservices Australia had
not intervened to create an exclusion corridor, such that each aircraft was rerouted on an ad-hoc basis as they came into range of PLAN broadcasts on guard frequency, how many flights would actually have been affected, and to what material extent? That is to say, to what extent were flight diversions exacerbated by the Defence Department initially declining to provide coordinates of the PLAN task force to Airservices Australia?
Needless to say, we are not going to get answers to these questions. Though Virgin, Emirates or PLAN could always release the radio logs of their interactions which would shed some additional light on the subject.