Someone mentioned DG as being conceivably within range dozens of pages ago. Then the subject of hangars there was mentioned. They're not big enough for the B-52's so they wouldn't be for a 777 either, judging by Google Earth. So that should be the end of that one....
And this has probably been done, but as for the 777 integral ELT, shouldn't SARSAT/коспас pick up any 406 MHz ELT's going off? There has mostly been discussion of search planes and Inmarsat. Sorry if it's a dumb question.