Trail to Air France wreckage started back in Portsmouth

PORTSMOUTH

Soon after Air France Flight 447 went down the night of May 31, Brazilian and French teams began combing vast sections of the Atlantic Ocean for signs of wreckage and survivors.

Behind this high-profile recovery effort, a group of local Coast Guard members has been doing its part with the help of a new simulation program that can look back in time.

The call came soon after the Airbus A330-200 went down on its way from Rio de Janeiro to Paris with 228 people aboard.

Coast Guard members at a research and development center in Groton, Conn., who had been in touch with their international partners, wanted to know whether the Coast Guard Rescue Coordination Center in Portsmouth might be able to use its new software to aid the effort.

The center had begun using the reverse drift modeling program just weeks before.

The software takes the time and location of an object discovered in the ocean - say, a body or a piece of wreckage - and, using the speed and direction of local winds and currents, projects a backward path to where it may have been when the plane went down.

The Air France crash presented the first major test of the new program, which is part of the Coast Guard's Search and Rescue Optimal Planning System, or SAROPS.

"It has proved itself to be extremely reliable, a fantastic tool," said Geoff Pagels, search and rescue specialist for the Coast Guard's 5 th District.

The first siting was of a seat cushion and other small pieces of debris. The Portsmouth team now had three variables in the equation: the time and location where the objects were found and the time the plane was believed to have gone down. Finding the fourth - the location of the rest of the plane - was the goal.

In the span of 15 minutes, the computer program is able to map up to 10,000 simulated paths that could have led the object to its current location. The program also projects into the future via a standard drift program, to see where other objects may have ended up.

Objects with different characteristics can be substituted for one another, said Jack Frost, the SAROPS program manager in Washington.

For example, if searchers found a seat in one location, the computer could simulate the body it held - which would have a different leeway, or reaction to the wind - and project it forward and backward in time, tweaking the currents and wind patterns along the way, in the hopes of finding it.

This technique, known as a Monte Carlo simulation, creates a stream of probable locations shown in different colors on a map, Frost said. The higher the probability in a particular area, the redder it is on the map.

These data are given a time stamp and geographic coordinates and sent to France, where searchers use the information to develop search patterns. If they aren't able to cover an entire area, they can pinpoint the hot spots.

The reverse drift software stands in high contrast to the way these types of tracks were formerly plotted, Pagels said.

Before computer modeling, a person would have to plot out a possible course by hand, using pencil, paper and static snapshots of past wind and current data. One simulation could take hours.

Nowadays, the Coast Guard has access to all sorts of real-time weather data and sophisticated forecasts, which can be pulled into the modeling program automatically.

In the Air France case, Pagels said it has been a back-and-forth process. As the French and Brazilians find wreckage and victims, they send the time and coordinates to Portsmouth, where Coast Guard members run forward and backward models, which the search teams then use to refine their search.

As the search teams find more objects, the Coast Guard runs more models. With debris from the wreck dispersed so widely, these simulations help the crews make more educated guesses. Early last week, Pagels said, this process helped searchers find part of the plane's fuselage.

The reverse drift software has applications for mariners as well, he said. It could be used if a lone body is found in the water, for example, or a pilotless boat. Courses in the modeling program are now being taught at the Coast Guard Training Center in Yorktown.

As for the Air France mission, Pagels said the recovery effort will end when the Brazilian military, which is running the mission, says so.

Until then, he said local Coast Guard members are more than happy to help.

"This is what we live for," he said. "This is the good stuff."

Matthew Jones, (757) 446-2949, matthew.jones@pilotonline.com