Airlines become weathermen as sensors upend forecasting models

DALLAS — As a storm predicted to deliver freezing rain and ice neared Dallas in November, airlines began canceling hundreds of flights. Not Southwest Airlines Co.

Armed with a new generation of sensors measuring moisture in the air on 87 of its planes, the airline had better data than the U.S. government’s twice-a-day weather balloon system. Its weather team knew the storm wouldn’t bring the ice that can snarl airport traffic.

“We saw it wasn’t going to happen here,” Rick Curtis, Southwest’s chief meteorologist, said about the Thanksgiving week storm. “It was too warm, and there were some dry layers in places in the atmosphere.”

The prediction of storms and atmospheric conditions such as turbulence is undergoing a revolution that could trim airline delays, cut costs and reduce in-flight injuries. Even incremental improvements in delays are important when late flights cost airlines as much as $8 billion a year.

By feeding better data into U.S. National Weather Service computer models, the devices are also helping the government make more accurate predictions, said Richard Mamrosh, a senior forecaster at the Weather Service’s office in Green Bay, Wis.

United Parcel Service has equipped 25 of its planes with the Houston-based SpectraSensors Inc. devices and, with Southwest, provides more than 50,000 reports a day across North America. American Airlines has started getting real-time turbulence reports, and Panasonic has helped outfit 225 U.S. planes with humidity-measuring equipment.

While the sensors have been placed on less than 1 percent of commercial aircraft, there are growing calls to expand their use. The sensor-equipped planes fly their regular routes, which under U.S. rules keep them away from the most severe weather.

Weather sensors on the ground are plentiful, yet much less is known about real-time conditions in the atmosphere


The Weather Service’s weather balloon program takes soundings only twice a day from 69 locations in the continental United States, according to the agency’s website. The data radioed to the ground can be as much as 12 hours old or hundreds of miles away from where meteorologists need it, Mamrosh said.

“We have the computing power to make much better forecasts than we do,” he said. “The thing that’s holding us back is the data above the ground.”

That’s where airliners come in. Scheduled carriers make more than 25,000 flights a day on average, Federal Aviation Administration data show, providing a far broader potential platform for weather sensing.

These technologies augment more rudimentary temperature and wind reports, which airlines have been transmitting since the early-1990s. Unlike the moisture and turbulence sensors, the reports require only a software change and no new equipment. They’re also less effective in predicting storms.

The number of aircraft sending the temperature and wind data has grown gradually and now as many as 500,000 observations a day are captured around the world, mostly in North America, Europe and parts of Asia, according to the National Oceanographic and Atmospheric Administration.

No one has quantified the benefits, but even small advancements count when weather causes about one-third of all flight delays. Total delays cost airlines more than $8 billion in 2007, according to Transportation Department data.

UPS’ Louisville, Ky., hub is nowhere near the closest National Weather Service weather balloon-launching site, making forecasting difficult, said Randy Baker, the senior meteorologist for the Atlanta-based shipping company.

In one instance, traditional forecasts predicted a frost overnight in Louisville. If frost sticks to planes, it requires spraying the aircraft with anti-icing fluid, costing “tens of thousands” of dollars, Baker said.

As aircraft started arriving near midnight, data from the new technology showed that the forecasts were wrong and there wouldn’t be frost.

“We were able to call the deicers and say, ‘Stand down,’ ” Baker said. “We saved quite a bit of money.”


After tests by NASA showed the value and accuracy of aircraft sensing of moisture, the government contracted in 2010 with Rockwell Collins Inc.’s Information Management Services division, to provide the data for $3 million from Southwest and UPS, a company statement said. The Rockwell division is the former ARINC Inc., which operates a data-transmission network for airlines and was acquired in December.

Although early aircraft data improved forecasts, it lacked information on humidity, which is key to predicting storm activity and other weather, said Patricia Pauley, a meteorologist and specialist in aircraft data at the Naval Research Laboratory in Monterey, Calif.

Knowing how much moisture is in the air makes it far clearer whether a front will produce thunderstorms — and when it will happen, Pauley said.

In California, which has only two weather balloon sites along the coast on the southern half of the state, National Weather Service meteorologists use the aircraft humidity data to determine when fog will occur, Mamrosh said.