@Mesoman.
I believe they have given some of your navy submarines surprises in exercises too.
I notice nothing is said about the extensive sonar type stuff in the area from both Australia and US.
My bet is this would be more significant than OTHR.
I wouldn't know about the subs, personally. I did help train Aussies and Kiwis in P-3's. I notice that the P-3C endurance (10 hours) is quite a bit less than in the old days - perhaps all the fancy electronics are heavy, or whatever.
I don't know if there is much sonar in that area (presumably, you mean SOSUS or simillar). I doubt it's a very high priority area, and I don't think SOSUS is as important as in cold war days.
Of course, we can't know about sonar. For all we know, SOSUS-like systems heard the crash or ditching. But I doubt it.