Long time lurker, have absolutely no experience in the industry other than by association. I'm totally in awl of the expertise and knowledge of the professionals here.
I'm inclined to believe that there was a decompression as this seems to be the most logical reason for the disappearance. I have just one question that after 150 odd pages doesn't seem to have been addressed. That is if in the early stages of hypoxia and associated confusion just how easy would it be to switch off the transponder in either error or in confusion with another procedure? ie is it just a simple switch or more elaborate process?
Thanks!