Team remains hopeful of locating missing jetliner

Searchers still have more than 50 percent of 60,000 sq km 'priority area' to investigate

Exactly one year ago, Malaysia Airlines Flight MH370 took off from Kuala Lumpur's airport and subsequently disappeared, leaving the world with one of the greatest aviation mysteries in history.

Four ships, each with a crew of 35 people, are working in 12-hour shifts scanning the southern Indian Ocean floor. Every 45 days, the ships return to Freemantle, Western Australia, to resupply. The round trip takes 12 days.