Trolling for Evidence

Air Safety Week, June 22, 2009

Investigators continue their search for the flight data and cockpit voice recorders from the Airbus A330-200 that crashed into the Atlantic Ocean on June 1, killing all 228 people aboard.

Air France Flight 447 had departed Rio de Janeiro bound for Paris. It flew into stormy weather and messages transmitted from the stricken jetliner indicated that inconsistent speed measurements could have played a role in the air disaster.

Autopsies revealing fractures in the legs, hips and arms of the victims, and discovery of large pieces of the fuselage, including an intact galley, strongly suggesting that the plane broke up in the air.

In Paris, Paul-Louis Arslanian, head of the French air accident investigation agency BEA, said search teams had recovered more than 400 pieces of debris -- reason for optimism. "We are in a situation that is a bit more favorable than the first days," Arslanian told a news conference at BEA headquarters outside Paris. "We can say there is a little less uncertainty, so there is a little more optimism."

French investigators confirmed more details about the crash of Air France Flight 447.

They have confirmed seven facts:

* The airplane was in cruise flight at 35,000 feet.

* No messages indicating problems were received on the air traffic control radio frequencies.

* Close to the planned route of the airplane above the Atlantic there were significant convective cells characteristic of the equatorial regions.

* The last position message from the airplane was broadcast by the ACARS automatic system at 2:10 universal time.

* Between 2:10 and 2:14 universal time, 24 maintenance messages were transmitted by the ACARS, including 14 between 2:10 and 2:11.

* Analysis of these messages shows inconsistencies between the various speeds measured. Most of the messages appear to result from these inconsistencies; they correspond to the loss of several flight assistance systems.

Still missing are the A320's flight data and cockpit voice recorders, thought to be deep under water. Ships are trolling a search area, pulling U.S. Navy underwater listening devices attached to 19,700 feet of cable. The black boxes send out 'pings' that can be heard up to 1.25 miles away, but these locator beacons will begin to fade in two weeks.

Meanwhile, the European Aviation Safety Agency (EASA) is mulling over whether to require all airlines to replace Thales-made pitot tubes on their Airbus A330s.

There are currently 600 Airbus A330 jets in revenue service, operated by 72 air carriers. After the loss of Flight 447, many carriers, including Air France, replaced the air speed sensors as a precaution.

Airbus had recommended replacingthe devices after determining that they could be susceptible to icing. Neither EASA nor the FAA considered the risks posed by pitot tube icing to be significant enough to justify making replacement of the sensors mandatory.

U.S. Coast Guard search and rescue (SAR) experts based at the Portsmouth, VA Rescue Coordination Center have assisted officials at the Rescue Coordination Center in Gris Nez, France, with the search for Air France Flight 447 by providing information and advanced technology to help locate the plane's fuselage.

The Coast Guard has assisted the French authorities by applying new, advanced SAR software system called the Search and Rescue Optimal Planning System (SAROPS) that generates optimized search area predictions for objects missing at sea.

SAROPS includes a "reverse drift" capability, which predicts a search area based on the location where floating wreckage is found. This enables search planners to develop optimal search patterns, maximizing the probability of successfully locating search objects.

By tracking information on when and where debris is found, the SAROPS system works backward using the weather, wind and sea conditions over a specified period of time to estimate a probable location of the plane. Based on this position, search efforts can be focused to find the plane's flight data and cockpit voice recorders.

SAROPS provides rapid and optimized search and rescue predictions by incorporating the latest real-time and forecast environmental data such as wind and currents. The SAROPS system was developed by Applied Science Associates (ASA), Northrop Grumman, and Metron for the USCG.

ASA delivers the crucial EDS: Environmental Data Server component of SAROPS, which quickly aggregates and feeds meteorological and hydrodynamic conditions to the SAROPS system. In search and rescue and recovery operations at sea, the faster responders can get accurate model predictions of search areas, the greater the likelihood is of locating persons in the water and floating wreckage.

"The software is designed to minimize data entry and the potential for error, resulting in more efficient recovery than ever before," explained Eoin Howlett, ASA's CEO and lead for the continuing development of the SAROPS system. "The ability to access a variety of data from satellite, in-situ observations, radar, and models allows the search and rescue controller to quickly evaluate possible scenarios."