http://www.dallasnews.com/sharedcontent/dws/bus/stories/110904dnbuspilot .78bb.html A pioneering experiment to let computers rather than pilots navigate airplanes on departure from Dallas/Fort Worth International Airport has been quietly halted after four incidents raised safety concerns.=20 The Federal Aviation Administration stopped the several-day experiment on Thursday after two aircraft flew too closely to each other.=20 Although officials said there was no risk of collision, the jets flew 2.78 miles from each other, less than the 3-mile minimum distance required by federal regulations.=20 The test, expected to resume within months, was part of an effort to add capacity for congested airports and relieve an overburdened national air-traffic system.=20 "We hope to get the testing back in operation very soon," said FAA spokeswoman Laura Brown. "We're tweaking some of the departure routes, and we had some performance issues."=20 She said the agency remains "very much committed" to the area navigational program, or RNAV.=20 Although there has been limited testing at some other sites, the experiment at D/FW marked the first large-scale operational test at a major U.S. airport.=20 In addition to the incident in which minimum separation rules were compromised, there were other minor events. They involved two aircraft turning toward the wrong runway and a third airplane missing a required turn after takeoff.=20 "RNAV has shown great promise, and we look forward to its implementation," said Jim Crites, D/FW's executive vice president of airport operations.=20 "As the FAA sees areas for improvements, we will support their efforts to work through those issues."=20 Delayed several times for various reasons, the next-generation navigation and air-traffic system has been on the wish list of the nation's airlines, airports and the FAA for years.=20 The idea is to use sophisticated positioning and navigation capabilities already on board airplanes to make takeoff and landing operations run more smoothly.=20 "The benefits can really be huge for the flying public," said Basil Barimo, vice president of operations at the Air Transport Association, which represents the major carriers. "Every flight out of D/FW could be shortened. Less time, less fuel burn, a more reliable flight path. It's all good."=20 The government made working on the air-traffic system a priority several years ago when the nation was facing gridlock at airports. Transportation Secretary Norman Mineta said last week that the Bush administration is working to triple the capacity of the nation's aviation system over the next 15 to 20 years.=20 "As we look ahead, the growth that is expected in aviation is staggering," he said. "This is true by virtually any measure from passengers, to operations, to air cargo. We are looking at threefold increases."=20 The regional navigation system being tested is supposed to help handle all of that. But the failed experiment at D/FW showed that there are still bugs in the program.=20 The major players spoke on Monday and plan a teleconference today to hammer out a solution.=20 "We're anxious to see this up and running. It looks like they have some very simple fixes," said Mr. Barimo. "Some of the capacity gains we're expecting over the next several years are certainly linked to utilizing RNAV."=20 Mr. Barimo said that one possible solution is to require carriers to use the autopilot.=20 "In this test they didn't require that the autopilot control the aircraft. Flight directors tell the pilot where to fly, but there is some element of pilot technique," he said.=20 Fort Worth-based American Airlines Inc., which was involved in the testing, is watching to see what happens next.=20 "We're very interested in this as it does save fuel and time," said spokeswoman Jacquie Young. "The FAA has some additional follow-up they'd like us to do. We anticipate starting the test again in the first quarter of 2005."=20 =20