Malt 68,
Bunbury is on 127.0 which it shares with Busselton and Capel and had done for some time before YBEV changed to 126.85. If this was part of the reasoning to change the frequency then it seems odd - as was the decision to do it in between update cycles. It's all very well to say people should read the NOTAMs but a lot of people don't, and certainly don't expect a new CTAF to appear half way through a cycle, so if situational awareness was the issue then why not do it when the new docs came out?
If you fly from YNTM to YBEV, within that 30 nm there are three different frequencies that overlap within the 10nm radii of Northam 124.2, York and White Gum 126.7 and Beverley 126.85; so there are areas where more than one frequency is correct and to some extent is open to interpretation, if you draw 10nm radius circles around them you get a venn diagram. This could lead to a breakdown in situational awareness due to two aircraft in close proximity and possibly climbing/descending/on reciprocal headings/staying clear of gliders being on different frequencies. I think it would be safer if it worked on the same principle as the Bunbury/Busselton/Capel or Murrayfield/Serpentine model. The analogy of Jandakot/Perth/Pearce doesn't stand up because they are controlled aerodromes so it would be ludicrous to have them all on the same frequency.
Fully aware of how glider ops work, rights of way and what a double cross means, thanks. Hence my surprise to see a tug plane in radio silence at a certified aerodrome doing a steep turn onto final at 300 feet on final to cut in front of my aircraft at 400 feet. My point is that people should communicate and if the pilot had an operational reason to do this then all they needed to do was say so and I would have far preferred to go around and let them make number one than have to do a collision avoidance manoevre at low level.
My point all along is that see and avoid is a lot easier if you are in radio communication.