The two major possibilities seem to be: (1) after her final transmission on 3105, AE switched to 6210 and, for whatever reason, there was a problem with 6210 and it was never received by Itasca or those in the vicinity. In this scenario AE flies on for several more hours and never transmits again on 3105 while in the air; or (2) after her final transmission on 3105 the Electra ran out of gas and the "crash and sink" scenario occurs very quickly since she was flying at 1000 ft. Given the circumstances, I find scenario (1) highly improbable. That is, AE could not afford to simply casually continue transmitting at regular, rather widely spaced intervals on a single frequency as if it was business as usual. The Itasca and others knew the situation was dire and they were listening intently on 3105 and 6210 (not just listening at predetermined intervals of time), but her transmission went abruptly from signal level 5 to nothing on any frequency. One can forcefully argue that she couldn't possibly have run out of gas (although AE herself said she was low on fuel and sounded absolutely frantic in her final transmission), but that assertion has its own set of requirements and unknowns (she definitely started with 1100 gal; she didn't encounter strong headwinds, etc.). As much as I find the post-flight research fascinating ---at this point in my understanding, I am unable to get over the hurdles outlined above.