K-129 went boom over 1,500 miles from Hawaii. SOSUS type systems are in the Mediterranean Sea, Norwegian Sea, the Middle East (Indian Ocean), just about anywhere there is water. Even in waters down to -18,000 ft. Russian subs were using deep water canyons to evade the shallower systems so the Navy built systems to track them.
The Naval Institute Guide to World Naval Weapons Systems, 1997-1998 - Norman Friedman - Google Books
While a plane as large as a 777 might not record well being surface noise when it splashed it would make a bunch of noise as it sunk and parts imploded which should stand out as a abnormality to a tracking array.