MH370: Searching in Indian Ocean more difficult because...
PUBLISHED ONMarch 28, 2014 8:50 PMByLinette Heng
He was the chief of the sea search operations that successfully located the wreckage of Air France 447 (AF447) plane in 2011, two years after its crash.
Mr Mike Purcell, senior engineer at Woods Hole Oceanographic Institution - a non-profit organisation which studies all aspects of the ocean, answers questions on the search for the Malaysia Airlines plane MH370.
IS THE SOUTHERN INDIAN OCEAN MORE DIFFICULT TO SEARCH THAN THE ATLANTIC OCEAN, WHERE THE AF447 CRASHED?
The southern Indian Ocean will be a more difficult search because the potential area is larger and the weather at the location may be disruptive.
We did not have to suspend operations during the AF447 search because of weather. That is more likely in the southern Indian Ocean where the weather may be more severe.
In 2011, our team scoured the Atlantic Ocean using three autonomous underwater vehicles (AUVs).
A quick look indicates the (southern Indian Ocean's) sea floor is smoother than the (Atlantic Ocean's). This should allow the AUV to increase coverage rate.
WHAT EQUIPMENT IS USED IN AN UNDERWATER SEARCH?
AUVs or towed vehicles are needed to search the sea floor. Obviously, ships are still needed to support the vehicle systems. As there is a necessity to search a large area, acoustic sensors are also used.
SHOULD AUVS BE INVOLVED IN THE SEARCH FOR DEBRIS?
Any steps that can narrow the search area should be accomplished before starting the underwater search as the AUVs search the sea floor at much slower rates than air planes that are searching the surface for debris.
HOW IS AN UNDERWATER SEARCH CONDUCTED AND HOW LONG WILL IT LAST?
Acoustic sensors are deployed on AUVs that swim at a constant height over the sea floor. The vehicles are slow swimming at about 3.75 knots (about two metres per second) and they swim a programmed track over the sea floor.
Each mission lasts about 24 hours and covers 90 to 140 sq km. The data is downloaded from the vehicle after it is recovered.
After checking the data, the vehicle gets new batteries and a new mission, and is put back in the water. If the data shows a possible target, the vehicle will swim to that area and take pictures.
The vehicle will descend 3,500m in about one hour and rise to the surface in 30 minutes.
There is a time limit, which is quickly running out, when trying to locate sea floor debris by listening for flight recorder pingers.
However, there is no time limit when searching the sea floor using acoustic sensors.
linheng@sph.com.sg
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