What is the state of airborne maritime surveillance in support of the sea surface search? It's not as robust as, say, having a RCAF P-3 Orion tasked to the search effort - is it?
Don't worry. Vietnam doesn't have any of the venerable P-3; but they have several more modern aircraft, and patrol vessels. They're also equipped with Mark 1 eyeball sensors. No need to underestimate them.
An Orion is apparently participating in the search though, just like dozens of other aircraft and vessels, a US one based out of Japan, if that makes you sleep better. Yet, no RCAF aircraft at hand, unfortunately.