The initial surface search effort focused on areas closest to MH370’s last known position at Waypoint IGARI near the intersection between the Gulf of Thailand and the South China Sea. The graphic above depicts a search radius of 250 kilometers that extended from northern Malaysia’s city of Kota Bahru to the southern tip of Vietnam. At one point, more than 40 vessels and as many aircraft searched the area for signs of the missing plane. The effort was as unprecedented as the disappearance itself.
After the second day, a limited search was conducted near Kuala Lumpur International Airport in the Straits of Malacca on chances the pilots attempted to return to the airport due to an emergency of some sort. After the fourth day, when suspicions developed that the plane may have turned back to the west, crossed the Malaysian Peninsula, and then flown northwest toward the Andaman Basin, surface searches extended north of Great Nicobar Island, about halfway up to Lower Andaman Island. India took the lead in the Andaman Sea, which is within its territorial jurisdiction. No signs of the plane were found, although there were numerous reports of debris, oil slicks, even luggage; all were determined to be unrelated to MH370. Reports of luggage near Banda Aceh were determined to be unfounded.
But even while India was making surface and air searches in the South Andaman Sea, the Bay of Bengal, and using infrared-equipped planes to scan isolated Islands, US, Chinese, Australian, UK, and New Zealand assets were redeployed to the Southern Indian Ocean. High-tech aircraft like the P-8 Poseidon and the P-3 Orion joined the search deep in the Southern Hemisphere. Even submarines were rumored to be working the waters off Western Australia.
By the end of the first week of the plane’s disappearance, the theory gaining dominance was that MH370 reversed course twice after leaving radar screens, and eventually flew into the waters west of Perth, Australia. The first flightpath reversal was believed to be at Waypoint IGARI where the plane did an about-face and flew northwest into the South Andaman Sea; the second turn was believed to have been somewhere over the South Andaman Sea, but an exact location remains unknown to this day. From that turning point, the plane was believed to have flown nearly due south until fuel was exhausted.
While nothing associated with MH370 has been found, even now, everyone who has followed the search effort has been reminded frequently that our oceans are inundated with floating debris of all kinds.
The Southern Indian Ocean surface search for debris from MH370 formally ended on April 30, 2014. All planes and vessels were withdrawn, and plans for an extensive underwater search went to drawing boards.
The following graphic by Andrew Heneen highlights many of the areas of greatest interest during the surface search.
In broad strokes, the initial effort west of Australia covered 4.5 million square kilometers (1.7 million square miles). Eight nations participated in the Southern Indian Ocean portion of the search: Australia, Britain, China, Japan, Malaysia, New Zealand, South Korea, and the United States; and together they flew more than 300 sorties.
On June 10, 2014 Australia’s ATSB signed an agreement with Fugro Survey Propriety Limited, an Australian subsidiary of Fugro, to conduct a bathymetric survey of the area believed to be where MH370 crashed into the Southern Indian Ocean. That formally moved the focus to a deep water search for the fuselage.
The CSIRO graphic above identifies what is known of the Tasman Outflow and other macro-features of the Australian Continent. The Tasman Outflow was identified in 2007. It’s source is said to be the Tasman Sea between southeastern Australia and New Zealand. It moves east to west and flows through the area identified as the most likely resting place for MH370. It is believed to flow through the Southern Indian Ocean all the way to the South Atlantic Ocean, via the southern end of the African Continent. That saltwater river of unspecified volume, deep in the Indian Ocean, has an average depth of about 900 meters. Its proximity to the MH370 search area makes it an important element in drift modeling and surface searches, if the plane actually crashed in the Southern Indian Ocean region.