So keeping a listening watch on 121.5 is a requirement and plays a part in PLOC?
I've thumbed through a few docs but can't find the Standard. Is it in ICAO, EASA, CAA or another regulatory publication?
And PLOC. Has technology, apart from SELCAL on iOS, come up with a solution? What about our SOPS? If company deem it necessary to have 121.5 on "box 2" could they have something about Ops Normal after x mins of silence in an otherwise busy volume of airspace?
I've also tried to research MORs about losses of contact to see if a FACTOR pointed towards a problem other than HF with, so far, no evidence.