ATM Modernization, Business & GA, Commercial, Military

Weather in the Cockpit

By David Jensen | June 1, 2000
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There was a time when avoiding weather was a tactical exercise. It involved the aircrew making route and/or altitude changes based on information received via on-board weather radar (with a range typically little more than 150 miles) plus updates by VHF voice radio or from the Aircraft Communications Addressing and Reporting System (ACARS) data link.

Soon it may be possible for air transport, business, commuter, and general aviation pilots to view in real time–and in graphic form–weather conditions well beyond several hundred miles by using multiple weather data sources and a data link. Air crewmen can also observe the history of weather conditions, to determine trends and, for example, the direction of a storm. In short, it would be little different than observing conditions on TV, on the Weather Channel.

Better Routing

With this bounty of atmospheric data, they can plan their diverted routes much farther in advance, even make route changes prior to takeoff. The data would allow more exact routing–knowing precisely the storm’s boundaries–thus saving both fuel and time. Charles H. Scanlon of NASA Langley Research Center, determined from studies that airlines could potentially save up to 5% fuel costs by granting aircrew a strategic view of weather conditions. More important, on-board weather data can help pilots avoid turbulence and potentially hazardous weather.

And such weather data would benefit persons in addition to the flight crew. With a heads up of possible upcoming turbulence, the cabin crew can better prepare passengers and plan duties such as food and beverage service.

Such would be the result of a U.S. National Aeronautics and Space Administration (NASA) safety initiative set in motion at Langley Research Center, which in turn is the result of a presidential commission on air safety. The initiative involved new technologies for both the air transport and the general aviation marketplaces. In this issue, we cover a program for the air transport program; next month, we will present new weather information technologies in the general aviation arena.

Real-Time Data

For air transport, NASA contracted in May 1998 with a team led by Honeywell to develop a worldwide weather distribution and display system. The five-year contract covers the Phoenix, Ariz.-based company’s work on an "end-to-end solution…to get timely weather information to and from the aircraft," says Keith Hughes, program manager. "We’ll get the information from a variety of sources–satellite images, ground weather services, other aircraft en route–process it, distribute it, and display it in the cockpit in near real time."

The program’s intent is to improve the weather information provided to the airline dispatcher, air traffic controller, and aircrews, according to Daniel Leger, project lead at Honeywell, who adds, "Ideally, for efficiency in decision making, all three would look at the same information."

Honeywell’s program is called WINN, for weather information network, and should not be confused with CWIN (cockpit weather information), which is an earlier NASA research program. Honeywell selected the following team members for the WINN project:

  • ARINC Inc.–for communications and distribution support.

  • Weather Services International (WSI)–for both raw and enhanced weather data within the United States.

  • The National Center for Atmospheric Research (NCAR)–for weather data sets to inform the pilot of such atmospheric conditions as convection, turbulence, icing, cloud ceiling, visibility and winds.

  • United Airlines–for user application and input, and simulator support.

  • Kavouras Inc.–for real-time, high resolution Nexrad radar and text information for cockpit displays.

  • SITA–for international communication service, using satellite communications courtesy of Inmarsat.

  • And the National Weather Service Aviation Weather Center (NWS/AWC)–for raw and value-added products: Sigmet (weather advisory), TAF (terminal aerodrome forecast), METAR (meteorological aeronautical radio) and others, for both national and international aviation-specific weather.

Honeywell serves as the systems integrator and also furnishes the airborne server and displays.

From Center to Aircraft

The team effort was critical for WINN, as no single company has a complete, effective solution to the weather problem. Gathering and presenting weather data requires several disciplines: meteorology, communications, information management, human factors, logistics and systems integration.

Team leader Honeywell also developed for the WINN program a worldwide data center, where the weather information is gathered from the National Weather Service, WSI, NCAR and Kavouras via satellite. The center processes and compresses the data, then transmits it in grid form to aircraft.

During testing with its company Citation, Honeywell used a telephone system for transmission while en route and used Gatelink when the aircraft was near an airport. However, it currently is evaluating other data links for the WINN system, including satcom and VDL Mode 2.

Inmarsat and SITA were contracted for the WINN program to provide weather data transfer to aircraft, but according to Steve Spaw, Honeywell project engineer. "If the operator has its own means to get data, then it’s just a software matter. They could use ACARS, HF, whatever."

Mix and Match

In the aircraft, the weather data is converted into a graphical format, using the Honeywell developed Cartographic Information System (CIS). The aircrew, thus, receives a graphical composite of satellite imagery, convective weather, icing, turbulence and data from ground weather radar.

On an aircraft display or a laptop computer, the graphic data can be layered, mix-and-match style, to the crewmen’s discretion, and be overlaid onto a flight plan. The on-board "server" that stores the weather data interfaces with the flight management system (FMS) via a 429 databus, which provides the nav data, as well as the aircraft’s heading, altitude and planned route. According to Leger, the graphic user interfaces, part of the CIS, will grant aircrews selected data–TAF, radar, Sigmet, METAR, etc.–with a simple push of a button.

The WINN system currently is on the Honeywell’s Cessna Citationjet. Its weather information has been presented on various displays, including a laptop computer.

"We can work on any [processing] system that is Windows NT compatible, so long has it has sufficient [64 megabytes of RAM] memory for the data" says Spaw. "Airlines likely won’t want to spend millions to integrate the system at first," he adds. "Initially, I think, airlines will go with an external system, like a laptop or notebook computer."

What Now?

What now for WINN? NASA plans to test the system aboard a Boeing 757 starting this summer. Honeywell also hopes to line up a B777 operator to test the system using satcom on oceanic flights. To further satisfy the NASA contract, Honeywell will integrate a turbulence sensor into the system.

For more information, visit Next month, we cover weather data in the cockpit of general aviation aircraft.

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