NEW YORK — Ronaldo Jenkins recalls the day a wall of cumulonimbus thunderheads appeared on his radar screen.

"I looked on the radar for the thinnest patch of the cloud system to go through and decided to go for it," said the 63- year-old former pilot for Brazilian carrier Viacao Aerea Riograndense SA, who was unable to fly under or over the clouds.

Jenkins, now a flight safety consultant for the union representing Brazil's airline companies, made it through the turbulence and lightning safely. Marc Dubois, the captain of Air France Flight 447 from Rio de Janeiro to Paris, wasn't as fortunate on June 1. In the early hours that day, his Airbus SAS A330-200 fell from the sky during a storm, killing all 228 on board. The cause of the accident is under investigation.

A system to provide more detailed weather information that may have helped both Jenkins and Dubois has been under development for at least four years by the U.S. Federal Aviation Administration and counterparts around the globe, according to the agency. The satellite-based upgrade of air-traffic management, primarily aimed at ascertaining aircraft positions more accurately, will have the ability to send real-time climate images and data to cockpits.

Seeing the severity of the storm an hour before reaching it "would have been useful" in the case of Flight 447, giving the pilot more time to find holes to fly through, said John Hansman, director of the International Center for Air Transportation at the Massachusetts Institute of Technology in Cambridge.

NEXTGEN IN WORKS

Martin Fendt, a spokesman for Airbus, would not comment on whether a system like the one under development would have helped Flight 447. The company is waiting for the accident investigation to conclude before making statements, he said by phone from Paris.

Air France-KLM also won't comment before the probe ends, according to a spokesman in Paris, who declined to be identified because of company policy. The plane sent 24 automated system-failure messages, including one indicating that the A330-200's speed sensors were faulty, according to Bureau d'Enquetes et d'Analyses, the French agency responsible for the crash investigation.

In the U.S., the proposed technology is called NextGen, for Next Generation Air Transportation System, and is estimated to cost the government as much as $22 billion to develop, according to the FAA. The Automatic Dependent Surveillance-Broadcast link, being built by a team led by ITT Corp., is slated to be operational by 2013, according to the FAA Web site. ITT, based in White Plains, N.Y., is a manufacturer of engineering products and communications systems.

FAA APPROPRIATIONS

The FAA, which is working jointly with the Commerce Department and military, expects to spend about $1 billion a year on the system, spokeswoman Tammy Jones said. It is seeking $865 million in appropriations for fiscal 2010, according to the House Subcommittee on Transportation, Housing and Urban Development.

"We want to get to generate forecasts so far in the future that we can generate routes" that avoid storms, said Jason Tuell, chief of science plans for the National Weather Service. That capability, not expected to be available until 2025, will depend on meteorologists and engineers developing a system that combines advanced numerical and higher resolution weather models with radar and satellite feeds, said Don Berchoff, the director of the service's office of science and technology in Silver Spring, Md.

UAL TESTS SYSTEMS

UAL Corp., parent of United Airlines, may not wait for the government's link. The carrier, the third-largest in the U.S., is testing satellite-based weather systems for its planes, said Megan McCarthy, a spokeswoman for the Chicago-based airline.

"Making the business case for this is the problem airlines face since safety records are already so good," said MIT's Hansman. There is the equivalent of one to two crashes per 10 million takeoffs and landings, based on his calculations.

The Washington-based National Transportation Safety Board reported 42 serious turbulence-related injuries and no fatalities in the U.S. over the past five years.

Every year, millions of airline passengers fly through a turbulence-prone band, known as the Intertropical Convergence Zone, when they cross the equator. In the 30 days to June 8, 38,716 flights crossed the equator with a scheduled seat capacity of 8.2 million, according to OAG Aviation Solutions, a unit of London-based United Business Media Ltd.

The Air France plane was in the convergence zone when it crashed into the Atlantic.

3-D HELPS PILOTS

The latest radar products are three-dimensional, such as IntuVue from Honeywell International Inc. in Morris Township, N.J., which helps pilots determine the height of thunderheads. The three-dimensional systems, introduced less than three years ago, are in a small portion of the commercial aircraft fleet, said Chris Benich, director of aerospace regulatory affairs at the world's largest maker of airplane controls.

Among airlines using IntuVue are Cathay Pacific Airways Ltd., Air Canada and Singapore Airlines Ltd., while the U.S. Air Force uses it on C-17 cargo planes, according to a list provided by Honeywell.

The cost for long-haul aircraft such as the Boeing 777 is about $335,000, said Bill Reavis, a Honeywell spokesman.