In San Francisco, David Mulholland no longer has to press the speed dial to confirm flight arrival times so his fleet of limousines and sedans can pick up passengers on time at San Francisco International Airport. Instead, he gets the information on his computer screen, straight from the nation's air traffic control system.

In Addison, Tex., Mark Taylor doesn't have to wonder about the exact locations of his 15 charter jets. He can see their whereabouts on an electronic map with a click of a mouse button.

The up-to-the-minute whereabouts of the more than 5,000 flights per day tracked by air traffic controllers can be of great use in the aviation industry. Dimensions International Inc. of Alexandria makes the data available to about 500 companies through a service called Flight Explorer, and starting today it will offer a scaled-down version to armchair travelers as well.

For $10 a month, people can see much the same data that an air traffic controller sees -- radar-generated position, speed and flight number, for example. The information comes over the World Wide Web and is updated every three to four seconds.

It's another example of the Web moving to the public information from the government that used to be out of reach. On their computer screens, people can now study company filings that formerly were available only in Securities and Exchange Commission reading rooms. Flight Explorer is one of the most impressive examples of this trend yet, as information generated by the Federal Aviation Administration's radar system is transmitted to the Web within seconds.

The brains behind the software is a team of 20 technicians and aviation specialists led by Berry Gamblin Jr., who spent 28 years with the FAA. Gamblin's experience gave him an appreciation for the hassles that airlines and the companies that serve them -- limousine services and caterers, for instance -- go through to get accurate information about flight positions, departures and arrivals.

The Flight Explorer team spent a year writing a product that interprets and sorts live data that is fed to Dimensions International from the FAA's Volpe National Transport System Center in Boston, which stores all flight information.

Airlines have always been able to get this kind of information by radioing their pilots or telephoning control towers at airports, said FAA spokesman Bill Shumann. But since 1992 the agency has also allowed airlines to retrieve minute-to-minute air traffic information through the Air Transport Association, an airline trade group.

Through a research and development agreement, the FAA devised a system to feed the ATA air traffic data -- with military and law enforcement flights filtered out -- and the ATA regulated the users of the data.

But to interpret the abundance of FAA data, airlines had to either use FAA software or write their own, which for many was costly and inefficient. But because this data didn't include weather, dispatchers at airline operations centers had to juggle various sources -- FAA data, weather agency updates and pilot reports, among others -- to piece together a complete picture of an aircraft's situation.

One of the major selling points of Flight Explorer is its one-stop service; it provides the FAA data plus weather conditions and airport information to a personal computer hooked up to the Internet. (The consumer version of Flight Explorer will not include information on a flight's weather conditions.) Dimensions International last month took in about $200,000 in revenue from the product.

Commuter airline American Eagle, a subsidiary of Fort Worth-based AMR Corp., has been using Flight Explorer for about two years at a cost of less than $250 a month. The software has made dispatchers' jobs much easier, said Brett Krone, manager of the airline's dispatch center in Dallas.

With the click of an on-screen button, dispatchers can choose to monitor only American Eagle flights from New York to Miami. Or they can see that a Dallas-to-Miami flight is headed into thunderstorms and redirect the plane.

The system allows dispatchers to track a greater number of flights at the same time and to review the history of a flight's path. If a flight appears to be straying from its path, the software alerts the dispatchers, who can assess the situation using the data on weather, wind speeds and other conditions.

In addition to managing their own flights, American Eagle dispatchers can also gather information about competitors' aircraft that fly to the same destinations. That can help them find the most efficient flight paths. Krone said American Eagle been able to shorten the distances of some flights to cut costs and gain a competitive edge.

The software is also used by small charter jet companies that don't have intricate dispatching systems, such as Dallas-based Million Air Interlink Inc. "I can explain to passengers that we're late because of weather and basically provide better customer service," said Mark Taylor, Million Air's charter sales representative. The company used to have to rely on forecast information from the National Weather Service.

Installing the corporate version of the software can be cumbersome. Most clients ask Dimensions International to provide technicians to help with the installation.

Flight Explorer isn't the only flight-information software available. FlightTracker from TheTrip.com Inc. of Denver has similar functions.

The cost of using FlightTracker varies more than it does for Flight Explorer because TheTrip.com charges users for each search they make. Users have accrued bills ranging from $100 to $12,000 a month, said TheTrip.com spokeswoman Donna Crafton.

TheTrip.com also offers a modified version of FlightTracker for free through its Web site. Users can find out a flight's departure time, speed, altitude and estimated arrival time. But like the consumer version of Flight Explorer, the free version of FlightTracker doesn't let users see a flight's weather conditions.

Neither will Flight Explorer's consumer version, which Gamblin predicts will appeal primarily to frequent fliers as well as private pilots and aviation aficionados.

A Look at ...

Dimensions International

Business: Develops software for government agencies and businesses, particularly in the aviation industry. Flight Explorer helps airlines and airport transportation and catering companies track commercial and charter flights, providing real-time data on aircraft location, weather conditions, flight speed, and other information.

Founded: In 1985. Flight Explorer was developed in 1996 by a team of 20 software and aviation experts and marketed in 1997. Consumer version entering the market today.

Web site: www.dimen-intl.com

Chairman and chief executive: Robert Wright

Headquarters: Alexandria