Navy, NOAA use high tech in search
- By Bob Brewin
- Jul 28, 1996
The Navy and the National Oceanographic and Atmospheric Administration wasted little time in responding to the crash of TWA Flight 800 this month, dispatching personnel, vessels and high-technology equipment to the crash scene off the eastern shore of Long Island, N.Y.
Capt. Raymond Scott McCord, the Navy's supervisor of salvage and the person in charge of the multiple-agency fleet conducting the search for debris from the Boeing 747 and its vital "black box" flight recorder, had already bought his ticket and was on an airplane by the time the Navy received an official request for help from the National Transportation Safety Board.
McCord has years of experience in his highly specialized field, which has included recovering pieces of the space shuttle Challenger after it exploded in 1986 and recovering the flight data recorder from a jetliner that crashed this year in the Caribbean Sea near the Dominican Republic.
"That was in 13,000 feet of water, and we found the data recorder on the first pass," a Navy spokesman said. "When a situation like this happens, we send in the pros."
As McCord started his journey by air from Washington, D.C., to Long Island, the NOAA ship Rude, a hydrographic research vessel, raced to the crash site from Point Judith, R.I., arriving at the scene on July 18, less than 12 hours after the crash. The Rude started searching for debris at noon that day with its on-board sonar gear.
At roughly the same time, Oceaneering Technologies, Upper Marlboro, Md., the Navy's salvage support contractor, rushed to dispatch its high-tech search gear to the site in response to an urgent request from McCord's office. The company trucked its gear to Point Pleasant, N.J., installed it on the MV Piroutte, a vessel leased for the operation, and then it too headed at top speed to the crash site.
Once on station off Long Island, the Rude and the Piroutte deployed towed side-scan sonars to search for pieces of the downed 747. Gary Kozak, regional sales manager of Klein Associates, Salem, N.H., which manufactured the Shallow Water Intermediate Search System (SWISS) side-scan sonar used by the Navy, said that despite news reports critical of the slowness of the search-and-recovery effort, "I think everyone involved has done a very good job in very quick time. Finding anything under the ocean is difficult; this is like looking for a needle in a haystack."
Kozak said SWISS locates objects by sending out dual signals from each side of the towed sonar device. These signals are then carried by cable back to equipment on the support vessel, where they are processed on a computer based on Motorola Corp. 68000 Series chips. Klein has developed proprietary software and signal processing algorithms that clean up the returned sonar signals, providing enough fidelity to discern even relatively small objects.
The software also integrates coordinates derived from the Global Positioning System (GPS) into the search track run by the sonar, "so the Navy can map the sea floor.... It also allows them to calculate the size, length and width of objects," Kozak said.
Differential GPS signals available off the coast of Long Island will provide position accuracy of 5 meters or better, Kozak added. The SWISS data is displayed on a high-resolution computer monitor and stored magnetic media.
The Rude operates a similar side-scan radar system, manufactured by Edge Tech, Milford, Mass. Rick Jablonski, district manager for Edge Tech, said his company's equipment can detect an item as small "as a 1-meter sphere down to a depth of 300 feet, depending on the [sea surface] as well as bottom conditions."
The Edge Tech side-scan sonar feeds its data into an integrated, shipwide hydrographic data acquisition and data processing system built around Hewlett-Packard Co. HP 9000 computers purchased through the Navy's Tactical Advanced Computer-4 contract.
Edge Tech's Jablonski said this system allows for easy integration of navigation and GPS data with the sonar track. "What they are doing is creating a navigation point for every sonar data point they gather in near-real time," Jablonski said. "When they get into post-processing, they can generate a mosaic map of the ocean floor and a particular grid of interest."
The Rude and the Piroutte will continue to run data acquisition tracks over the crash scene until every possible bit of debris has been located, the Navy spokesman said. While the technology is more than suitable for the job, Jablonski said it is not an easy task.
"It's one thing to take this equipment out in a sunny day, in calm seas to look for treasure.... It's another to operate this in rough seas, with all the pressure that surrounds this tragedy," he said.