KUALA LUMPUR: The southern Indian Ocean, where investigators suspect missing Malaysia Airlines Flight MH370 may have come down, is one place where a commercial airliner can crash without a ship spotting it, a radar plotting it or even a satellite picking it up.
The empty expanse of water is one of the most remote places in the world and also one of the deepest, posing potentially enormous challenges for the international search effort focusing on the area, one of several possible crash sites.
Even Australia, which has island territories in the Indian Ocean and sends rescue planes to pluck stricken yachtsmen from the cold, mountainous seas in the south from time to time, has no radar coverage much beyond its Indian Ocean coast.
“In most of Western Australia and almost all of the Indian Ocean, there is almost no radar coverage,” an Australian civil aviation authority source said. “If anything is more than 100 kilometres offshore, you don’t see it.”
The Indian Ocean, the world’s third largest, has an average depth of about 3,600 metres. That is deeper than the Atlantic where it took two years to find wreckage from an Air France plane that vanished in 2009 even though floating debris quickly pointed to the crash site.
So far, search operations by ships and aircraft from more than a dozen nations have failed to find even a trace of flight MH370, which went missing more than a week ago after taking off from Kuala Lumpur for Beijing and diverting from its intended flight path.
The search effort has focused mainly on the South China Sea but is switching to the Indian Ocean after investigators, having pieced together radar and satellite tracking data, began to suspect the plane had been deliberately flown hundreds or possibly thousands of kilometres off course.
Searchers still face a daunting array of possible last locations for the plane, including the northern end of the Indian Ocean as well as central Asia, although investigators say it is more likely to have flown to the south than through busier airspace to the north where it could have been detected.
With an estimated four hours’ fuel left when last spotted by radar off Malaysia’s north-west coast, the plane could have flown a further 3,500km or so, assuming normal cruising speed and altitude.
Officials think the aircraft flew south until it ran out of fuel and crashed into the sea, according to a source familiar with data the US government is receiving from the investigation. In the south, any debris from MH370 would have been widely dispersed by Indian Ocean currents in the week since it disappeared.
The southern Indian Ocean, between Indonesia and Australia, is broken up only by the Australian territories of Christmas Island, home to asylum seeker detention facilities, and the Cocos (Keeling) Islands, about 2,000km north-west of Perth. The Cocos Islands have a small airport to serve the islands’ combined population of just 3000 people.
Further south, the only habitation is a handful of research stations on the scattering of tiny French-run islands including Kerguelen — a group of volcanic outcrops between Africa, Australia and Antarctica.
The shipping route from Western Australia north to Asia and Europe is considered relatively quiet in global shipping terms, despite the large amount of iron ore and other resources that are shipped from Australia’s north-west ports.
Ships track north, staying close in to the West Australian coastline, and then head north through Indonesian waters into the South China Sea or north-west towards the Red Sea.
Australia’s civil aviation radar extends a maximum of just 410km off the coast, the civil aviation authority source said, and was used only for monitoring scheduled aircraft on approach into the country and subsequent landings.