why not go under water. and i think this does give them a measure of comfort in saying, look, they're going to give it a shot. it's, as you say, an around-the-clock operation, keep going on for 10 to 12 days when they keep getting more models in about where the plane may have gone into the water or accurate information. they will continue to refine that search. i spoke to the lead commander on this earlier today, and he's definitely hopeful. he says the conditions are good. if it is pinging, he says his >> our paula newton reporting live in perth, australia. thank you for that. and joining me, cnn aviation correspondent, richard quest. >> good morning. >> good morning to you. and not only a terrific resource on this, and aviator, former royal air force lieutenant colonel, michael kay. and ocean explorer and expedition leader, christine dennison. and your insights become even more critical, as now the search goes under water. richard, start with you. four weeks ago, i did not think