Regional airline pilots soon should be able to tap into a more detailed and real-time picture of weather problems than what they have now - even comparable to what pilots for some larger carriers now use - thanks to technology supported by the National Aeronautics and Space Administration (NASA).

For a long time, there's been significant interest in getting better, real-time weather data to pilots in regional and general aviation, says Taumi Daniels of NASA's Langley Research Center, who served as the agency's project manager for a year-long demonstration of AirDat LLC's Tropospheric Airborne Meteorological Data Reporting (TAMDAR) system in the Great Lakes region. Poor weather is a contributing factor in about 30 percent of all accidents.

AirDat technicians installed TAMDAR sensors aboard about 60 Saab 340s operated by Mesaba Airlines for Northwest Airlines [NWACQ.PK]. In each aircraft, a technician installed a TAMDAR sensor, which approximates the size of a first-generation home camcorder. On every run, each airplane takes soundings of surrounding atmospheric conditions, and transmits the data back to a weather forecasting station. Each sounding records several types of weather data. Although NASA's demonstration ended in January, Mesaba is still using the equipment.

The FAA and the National Oceanographic and Atmospheric Administration (NOAA) also were partners in the demonstration with Mesaba.

By comparing TAMDAR with today's system of atmospheric readings, it is readily apparent what some of TAMDAR's advantages are. The current national network of nearly 70 weather balloons take on average only two soundings a day.

But if nearly every regional and commuter aircraft in the country took soundings every two minutes of flight time, the additional data would present a more detailed, real-time picture of weather conditions. It also would mean far less interpolating for weather forecasters who try to fill in the gaps on weather maps, and less guesswork for pilots trying to avoid severe weather.

The 70 weather balloons in today's system take at most 140 daily soundings nationally, AirDat's vice president of operations, Rick Ferguson, tells Air Safety Week. With Mesaba using TAMDAR departing from about 75 airports in the Great Lakes region, there has been about 800 soundings on a typical day.

Because data is taken more frequently from more points on the map, and from a greater range of altitudes, there is "higher resolution forecasting" using denser grid spacing, he adds.

Regional Aviation News asked Ferguson if there could be temporary data drop-outs as readings of severe weather come in from certain routes, which are then avoided by pilots seeking clearer routes. Ferguson agreed that's a possible scenario. But "once we understand the behavior patterns of pilots, we can adjust our ground-based processing systems."

TAMDAR "was conceived to overcome some of the limitations of existing atmospheric sounding technologies, including radiosondes and ... MDCRS," AirDat says. TAMDAR focuses on lower altitudes in the troposphere that most larger commercial airlines fly over. It also adds to the usual data on temperature, pressure, and winds measurements provided by ARINC's Meteorological Data Collection and Reporting System (MDCRS), with additional data on humidity, icing and turbulence, AirDat says.

Moreover, TAMDAR is intended to address present-day inaccurate weather forecasts that stem from insufficient data collection in the troposphere, NASA's Daniels says. Once they're using it, airlines and pilots will be able to make better informed decisions. Neither Ferguson nor Daniels is aware of a competing system for TAMDAR in any stage of development.

For now, the data is interpolated for various on-screen presentations, which are seen by dispatchers and reported to pilots, Ferguson says. Someday soon, pilots may be able to see the same information via an intranet on their laptop computers.

Overall, TAMDAR's "biggest advantage" is that data comes "from locations where we've never had data before," says Rich Mamrosh, a National Weather Service (NWS) meteorologist based in Wisconsin who is well versed in TAMDAR. For Wisconsin, until recently, forecasters had to rely on just three weather balloons. There's a balloon that takes soundings twice a day in Green Bay, another in International Falls, Minn., and a third in Minneapolis. But under the new system, there's about a dozen airports within the triangle formed by those three cities that are now used by TAMDAR-equipped Mesaba aircraft.

At NOAA's Aviation Weather Center in Kansas City, Mo., forecasters issue regular weather advisories and warnings to pilots around the country. Depending on when and where the balloons are, and erring on the side of caution, these messages have to be fairly broad, Mamrosh tells Regional Aviation News. After one sounding picks up icing conditions, a forecaster may have to extrapolate that information to cover the airspace across four to five states.

Meanwhile, MDCRS is limited to the seven commercial airlines that have it aboard their planes, and it focuses mostly on wind and temperature data, NASA's Daniels adds. Data from it also tends to center on the major hubs those airlines most frequently use. But once TAMDAR is in place on more regional aircraft around the country, there will be "much better spacial and temporal sampling of the atmosphere."

"NASA considers [TAMDAR] a major success," he adds. There has been a reduction in error for temperature forecasting of 20 percent. For humidity and winds, the figure is 10 percent. "These are very significant results in numerical forecasting," Daniels insists. Also, the real-time observations from TAMDAR greatly improve existing weather products that map out turbulence and icing conditions.

NOAA says Mesaba was chosen because of its large prop-jet fleet, which flies in an area with "many meteorological phenomenon," and flies to and from destinations that coincide with NWS radiosonde locations, thus allowing a comparison of TAMDAR to radiosondes. The Saab 340, in particular, was chosen because it flies shorter flights at lower altitudes than many regional aircraft.

Meanwhile, Bill Poerstel, Mesaba's vice president of flight and technical operations, calls the demonstration a "successful partnership," which the carrier also might choose to expand. But he could not remark on how well TAMDAR improves weather forecasts or aviation safety.

AirDat also inked a deal to start installing its TAMDAR sensors on Horizon Air's planes. The company did not respond to Regional Aviation News' requests for comment by press time.

More information on TAMDAR is online at http://www.crh.noaa.gov/tamdar.

>>Contacts: Rick Ferguson, AirDat, (919) 653-4351, Taumi Daniels, NASA, (757) 864-4659, taumi.daniels@nasa.gov; Rich Mamrosh or Gene Brusky, NWS, (920) 497-8771, Richard.Mamrosh@noaa.gov or Gene.Brusky@noaa.gov; Elizabeth Costello, Mesaba, (651) 367-5264<<