These days the ATSB merely jumps to a convenient conclusion and doesn't bother pursuing anything that might cast doubt on that conclusion. Here's what the AAAA submission to the ASRR Panel says on this issue:
AAAA expressed strong concerns to ATSB management with previous attempts during investigations to attempt to mould evidence to fit a theory, rather than objectively analysing and presenting the evidence available.
That the Laborials are prepared to acquiesce in the ATSB's refusal to retrieve NGA's OBRs is a very sad indictment on the weakness of the fabric of government in Australia.