November 1, 1999. Copyright 1999. Graphic News. All rights reserved.

SUPER SONAR TO AID EGYPTAIR SEARCH

LONDON, November 1, Graphic News: THE U.S. Navy has sent the sonar-equipped search and recovery ship USS Grapple to help speed efforts to locate wreckage from EgyptAir Flight 990, which crashed into the Atlantic Ocean early on Sunday with 217 people on board.
USS Grapple is equipped with sophisticated search gear that will allow it to scan the ocean floor and locate debris from the plane.
U.S. Coast Guard, Rear Admiral Richard Larrabee, said the USS Grapple would help locate the Boeing 767Õs Òblack boxÓ flight data and cockpit voice recorders, which will be crucial in determining the cause of the crash.
ÒOne of my concerns right now is locating and recovering the black boxes,Ó Larrabee told a news conference in Boston. ÒThe boxes have a pinger on them. We donÕt currently have the ability to listen to that pinger.Ó
Grapple is the newest of the NavyÕs rescue and salvage ships and was involved in the search for the wreckage of John F. Kennedy Jr.Õs plane after it crashed in July, as well as recovery efforts after the Swissair disaster near Halifax, Nova Scotia in September 1998 and TWA Flight 800 in July 1996.
Once USS Grapple reaches the site of the planeÕs debris field, 60 miles (100 kms) south of the Massachusetts resort island of Nantucket, it will deploy a newly-developed, super-sensitive Synthetic Aperture Sonar and a Laser Electro-Optics Identification System, both of which will provide detailed images of the ocean floor.
The equipment is attached to a ÒsledÓ that is towed behind a ship. Two sonar units, affixed to either side of the torpedo-shaped sled, act as both sound sources and listening devices. These units emit bursts of sound outward, to either side. If the seafloor is flat and smooth, none of the energy emitted will be reflected back Ð as with a beam of light directed obliquely onto a mirror Ð  but if the seafloor is covered with debris then the sound hitting the bottom will be scattered in all directions, and some will return to the sonar sled.
By equating the strength of the recorded echoes to different shades of grey and displaying the results to show the distance from the sled, scientists on the Grapple can obtain an image of the texture of the seafloor that looks similar to a black-and-white photograph.
When the locations of the black boxes have been identified the Grapple will deploy its team of 20 divers plus an additional 12 divers from the Mobile Diving and Salvage Unit, Norfolk, Va.
The divers work in 8-hour shifts, spending an hour at depths of up to 200 feet (60 metres). Visibility in the icy-cold water will be between 8 and 10 feet (2.5 and 3 metres), with unpredicable currents amongst the aircraft debris. Their most arduous task will be to recover the victims from among the wreckage before raising the debris itself.
The National Transportation Safety Board, which is responsible for investigating the cause of the crash, asked for the Grapple to aid the recovery.
Two FBI agents have also been flown to the scene to ensure that evidence is properly handled as it is recovered so that the investigation can proceed.
/ENDS