>Is there some good explanation, show a sinking titanic was heard both in london and new york, but a modern(...ish) MH-370 can just dissapear?

If Titanic had sunk in the Indian Ocean, it would probably still be lost.

By sinking in the North Atlantic it was within radio range of dozens of other ships and ground stations. Carpathia got to it in 3 hours.

The part of the Indian Ocean that MH370 is thought to have gone down in is second only to the South Pacific in emptiness.