A Fish and a Robot search for Flight 370

A fish and a robot search for Flight 370 Towing an underwater microphone “fish" and hoping to deploy a deep-sea robotic surveyor, the crew of the Australian ship Ocean Shield concentrates its search for Malaysia Airlines Flight 370 in a 30,000-square-mile area about 1,400 miles northwest of Perth. With the batteries on the missing aircraft's "black boxes" expected to die at any moment, it has become a race against time to extract as much information as possible to narrow the search. Since March 18, the Australian Maritime Safety Authority has searched the southern part of the Indian Ocean. Directed by Subsea satellite probability curves based on search area Wharton earlier contact with the plane, the April 9 search has combed over and aban- doned areas as different theories and analysis have become available. I ndiaп The hunting grounds for Flight 370 O cea n debris gradually shifted futher north until last week when a Chinese ship towing a pinger Perth locator picked up a signal from what was possibly a black box Previous Basin beacon. This has shifted the search search area once more in a areas race against time to narrow Perth • the search before the batteries in the plane's locator beacons die. AUSTRALIA 200 MILES The subsea search area Tools of the search After the Chinese vessel's initial signal pickup on April 4, a subsea search area was created covering On April 9, 15 aircraft and 14 ships were involved in the search. But the focus in recent days has been on the Ocean Shield, which is largely working apart about 20,000 square miles of ocean following one satellite- from the other vessels. If other ships crowded that area, projected flight path. they would create noise and interfere with detection of sounds coming from the three-mile depths. 20,000 ft THE OCEAN SHIELD Since April 5, the Australian navy ship Ocean Shield – equipped with a U.S. Navy black-box detection system – has picked up April 6 and 8 four separate transmissions, the two most recent of which Ocean Shield were detected April 8. The newest signals are significant picks up four signals, two on each day. because the increased data could allow searchers 16,400 ft to more accurately target the location on the Indian Ocean floor where the sounds are originating. 13,200 ft Length 347 feet SEE DETAIL BELOW **........ Width 69 feet Draft 22 feet ......... Gross tonnage 8,368 6,600 ft Speed while towing 1 to 5 mph 9,800 ft 13,200 ft Cable 16,400 ft 20,000 ft 20,000 ft or more TOWED PINGER LOCATOR Width 36 inches To detect pings from an aircraft's black box, Weight 64 pounds the ship tows a winged pinger "fish" locator, Maximum cable 55,000 feet which carries a microphone that can detect Maximum depth 20,000 feet Indian frequencies from 3.5 kHz to 50 kHz. Black box Currently towed at 10,000 feet Ocean pings usually transmit a 37.5 kHz signal every second. The ping frequencies picked up by the Ocean Shield have been at 33.331 kHz. 20,000 ft NAVY If the batteries are dying, it is possible that no further signals would be heard. If no further data is obtained, the Bluefin-21 robot would still be deployed, but covering the current search area could require months. AUTONOMOUS UNMANNED VEHICLE 16,400 ft Detection of additional pings would help narrow the Acoustic communication search, at which point an untethered robotic deep-sea equipment relays information, drone – named Bluefin-21 – would use sonar such as GPS location or 20,000 ft equipment to search for wreckage at the bottom of the system health, topside. Indian Ocean. If no more pings are heard, searches will still deploy the robot. Some of the equipment installed on the Bluefin: April 4, 5 Approximate area of signals received by Hai Xun 01 A storage module records mission data, which are downloaded onto a computer 16,400 ft after the vehicle resurfaces. Navigation equip- ment determines 40 Lithium-polymer position above the MILES batteries are ocean floor. replaced after 500-square-mile focus Sidescan every mission. sonar equipment The Ocean Shield has detected Width 21-inch diameter four pings, all within about 25 An avoidance system prevents Length 16.2 feet ********** ******* miles of one another, although Weight 1,650 pounds ......... * the robot from colliding with underwater acoustics can create slopes or debris in its path. Maximum depth 14,763 feet a complicated pattern of sound waves from a signal. The search area generally shrinks with each additional ping sequence heard. A SLOW SEARCH "MOWING THE LAWN" April 6 2 hours, 20 minutes The Bluefin operates on autopilot based In the pitch darkness, the vehiçle makes on the instructions uploaded to its overlapping, back-and-forth passes over computer by the operator. Moving at about the bottom while taking high-resolution images with its sonar equipment. The April 6 13 minutes 4 miles an hour, the vehicle follows the contour of the terrain below it, maintaining vehicle can survey up to 40 square miles a position of about 160 feet above the during its 20-hour mission. ocean floor. April 8 Five minutes, 32 seconds SEARCH PATTERN April 8 Seven minutes (approx). 160 ft 25 square miles 120 ft. ........... 80 ft. 40 ft. WHEN THE MISSION ENDS The robot resurfaces and is hauled aboard the ship. The data storage module is removed and the high-resolution sonar images are downloaded to a Sources: Australian Maritime Safety computer for analysis. Sidescan sonar imaging - Authority, Marinetraffic.com, Bluefin as shown in the ample – has a range Robotics, Phoenix International, U.S. of 500 meters to the right and left of its "nadir," Navy, BBC news and staff reports a blind spot not covered by sonar. The Bluefin PATTERSON CLARK, RICHARD JOHNSON, makes back-and-forth passes to fill in this void. TODD LINDEMAN AND GENE THORPE/ Nadir THE WASHINGTON POST