New Delhi, March 22: The search for the missing Malaysia Airlines aircraft may be even more challenging than the hunts for an Air France plane that crashed into the Atlantic near the Equator five years ago or the legendary Titanic, consumed by the northern Atlantic 102 years ago, experts said.
The southern Indian Ocean, the new search zone for Flight MH370, which has been missing two weeks, will pose greater geographical and logistical difficulties than the Atlantic Ocean, oceanographers and air accident investigators said.
“The vast expanse of the southern Indian Ocean, its distance from the continents, and the depth and the behaviour of the ocean water will all make this search tough — really tough,” said S. Prasanna Kumar, head of physical oceanography at the National Institute of Oceanography, Goa.
The search for the Beijing-bound Boeing 777-200ER that vanished from radar screens about an hour after taking off from Kuala Lumpur moved into the southern Indian Ocean earlier this week after Australian authorities reported that satellites had picked up unidentified debris there.
While there is no indication yet that the debris was from the missing plane, Australian aircraft have flown over the area in the past two days looking for signs of MH370. Ships are now sailing towards the search site, about 2,500km west of Perth, Australia.
“But planes can only spot floating debris. Ships equipped with acoustic instruments will be needed to probe the ocean depths,” said M.A. Atmanand, director of the National Institute of Ocean Technology, Chennai.
“It could take ships four or five days to reach the search zone from Australia.” The search zone is about 3km to 4km deep, comparable to the depths in the southern Atlantic where the Air France flight AF447, flying from Rio de Janeiro, crashed in 2009 and in the northern Atlantic where the Titanic sank after hitting an iceberg in 1912.
A US-French expedition led by American Robert Ballard found the wreck of the Titanic at a depth of 3,800 metres in 1985, relying on automated underwater vehicles (AOVs) for deep-sea exploration that were unavailable in earlier decades. Although some debris and a few bodies from the AF447 were found within a week of the accident, it took two years for the main wreckage to be found on the ocean floor.
But in both those earlier accidents, authorities had a fair idea where to look for the wreckage.
“Here time is running out. The longer the delay in finding the debris, the harder it will be to find it,” Kumar said.
The southern Indian Ocean, he said, has several zones of convergence where relatively warm water and cold water mix and circulate in the ocean. The surface of the ocean too has currents that can disperse floating debris.
“The currents may disperse debris and the convergence zones may drag it downwards towards the bottom,” Kumar said.
Aircraft accident specialists say how much debris will remain afloat two weeks after a plane has hit water will depend on how the aircraft broke up on impact.
“Composite parts, particularly those that use honeycomb materials, will tend to float initially due to the trapped air,” Matthew Greaves, professor of aircraft accident investigations at Cranfield University in the UK, told The Telegraph.
“Seat cushions and life jackets, if inflated, will also be expected to float, but whether they will still remain afloat after 14 days is a real question.”
The size of the debris field will also depend on how the aircraft broke up. The wreckage of the Air France plane, which had hit the surface of the Atlantic Ocean intact, spanned an area of 600 metres by 200 metres.
Scientists say the search for wreckage in the deep ocean is difficult even with acoustic instruments.
“Acoustic techniques we use from the surface lose resolution with water depth,” said Martin Jakobsson, professor of marine geology at Stockholm University who has been involved in the search for old shipwrecks.
So, in deep water, search teams typically use low-frequency multi-beam sonar and get images with lower resolution, or less sharp images.
The best way to look for underwater wrecks, Jakobsson said, is to use deep-sea submersibles towed by ships or AOVs equipped with acoustic instruments that are good for probing the deep sea.
The ocean-bottom topography may also pose a challenge.
“A target may be very difficult to find if the sea floor is rough or contains geological features that may hide the wreckage,” Jakobsson told this newspaper.
Kumar said the many sections of the bottom of the southern Indian Ocean that have been mapped do not show a flat basin unlike parts of the Bay of Bengal but contain features such as seamounts and ridges that could complicate the search.
“But modern techniques to search the ocean bottom are very good,” Jakobsson said.
“And persistence will pay. Eventually someone will hopefully find the plane.”