Wireless radio frequency (RF) local area networks (LANs) are emerging as an alternative to wired networks in homes and offices, promising both flexibility and convenience. It is only a matter of time before the technology goes aloft. There it could provide lightweight, mobile, paper-free data communications for both the cabin and crew.
Wireless aircraft local area networks have not yet been approved for crew and cabin applications for large planes in domestic airspace. However, the U.S. Federal Aviation Administration (FAA) has certified a networked, airborne wireless smoke and fire detection system by Securaplane on MD-80, DC-8, DC-9 and B737 aircraft, which sets a precedent. German aviation authorities also have approved Rockwell Collins’ wireless LAN for trials with Condor, a charter airline owned by Lufthansa.
Though different in frequency and operational use from oncoming wireless LANs, the Securaplane detection system has expansion capabilities, the company says. Securaplane has installed systems on about 1,000 aircraft with carriers such as Southwest, U.S. Airways, UPS, DHL and America West.
There are hundreds of possibilities for higher-data-throughput, on-board wireless LANs, including pilot e-mail, graphical weather updates, passenger duty-free purchases, credit card validations, passenger e-mail, surfing of stored Web pages, and cabin attendant problem reporting. Avionics suppliers such as Collins, Honeywell and GE Harris Aviation are pursuing air- and ground-based versions of the technology.
Condor is testing airborne and ground-based applications of Collins’ wireless LAN. Collins also expects to begin trials with American Airlines, using a wireless LAN to forward satellite-uplinked weather updates to pilot laptops on Pacific routes.
Graphical weather updates, a development project partly funded by NASA, could make a big difference to pilots, who now rely on voice messages for updates on developing weather patterns beyond the range of on-board weather radar. The upshot could be a strategic cockpit tool.
Honeywell also has certified an e-mail application of its Total Aircraft Information System (TAIS) on its corporate jet. The company is focusing on the business jet market, where it sees a better business case than in the air transport market, says Steven Irwin, Honeywell’s product marketing manager.
Collins and Honeywell use spread spectrum technology–at around 2.4 GHz–standardized in the Institute of Electrical and Electronics Engineers (IEEE) 802.11 spec and called out in ARINC’s 763 "network server system" standard.
Condor’s tests on several A320s have focused on pilot e-mail. In non-critical phases of flight, messages can be sent wirelessly from a laptop computer to the on-board file server, explains Dave Behmer, director of Integrated Information Systems (I2S) for Collins Air Transport Systems. In the current implementation, e-mail is transmitted to the terminal when the aircraft reaches the gate. But Behmer envisions more real-time capability when a high-speed data link becomes available (see Nokia sidebar).
Collins’ planned graphical weather data trial will overlay weather updates on pilot laptop color map displays. The data, generated by Jeppesen and uplinked via WorldSpace’s Asiastar satellite, will be stored in the aircraft’s 763-standard file server. From there, it will be forwarded to the pilot’s portable computer via the wireless LAN. (Mapping software is preloaded.)
The American Airlines trial, on two 777s, will take place on routes between the United States and Japan, Behmer says. The application will allow satellite weather data to be viewed in the cockpit in an easy-to-grasp format. Worldwide graphical weather coverage has not yet been demonstrated using satellite digital broadcast capability, he adds.
The tool will enable pilots to "make more strategic analyses of weather conditions ahead" and determine whether and how to fly around a problem much earlier than would be possible with radar, alone, Behmer says. Current aircraft weather radar reaches out about 100 to 150 miles.
The FAA Viewpoint
Before wireless technology can take off in aircraft, electromagnetic interference (EMI) issues need a hard look to satisfy concerns about the effects of possible conducted and radiated emissions. Airframers and avionics suppliers have been and continue to be engaged in these tests. An FAA official predicts approval of in-flight systems in a year or two.
But the crux of the matter is not the on-aircraft installed equipment, which can be closely scrutinized, but the expected influx over the next two years of wireless technologies in laptops and other devices. These cards and internal modems may include technologies in addition to the one contemplated by avionics suppliers. And the effects of numerous cabin transmitters are not well understood. FAA is concerned that these mass-market devices could malfunction and output at a higher power level than is allowed or generate spurious out-of-band emissions.
"EMI is something you’d have to assure yourself on," says Derek Anderson, a senior avionics engineer with Boeing Commercial Airplanes. "Whenever you look at transmit devices, you have to look at their effects on other systems." He predicts that ground-based applications will be realized first because carriers see them as a means of increasing their operational efficiency. But the technology is coming, he says, and Boeing is "prepared from an ARINC 763 perspective" to meet carriers’ needs.
Weather applications bring up other issues, FAA says. Under what circumstances should pilots depend on off-the-shelf hardware and software? Could data transmissions be corrupted inside the computer? What is the risk if the information were wrong or not there? Mass-market computers lack "high integrity" in FAA’s sense of the term.
View from Nokia
Nokia, the mobile phone giant, is confident about the future of wireless on-board data communications. IEEE 802.11-standard on-board wireless equipment will meet FAA safety standards, says Bill Singley, director of business development for this area.
Nokia would serve as a supplier of aircraft RF "access points," devices that "transmit and receive 2.4-GHz signals" for ground and in-flight applications, Singley explains. But the real market is on the consumer side, the RF cards destined for laptops and other computers. Nokia sees potential sales of at least one million units.
Singley predicts that airlines will offer store-and-forward e-mail services at no cost. (Store-and-forward means that messages are stored on the aircraft server and forwarded when the aircraft parks at the gate.)
Corporate customers who for security reasons are not allowed to use store-and-forward e-mail service, eventually will avail themselves of a virtual private network (VPN) encrypted link using a high-speed satcom down link. Boeing, for example, is developing a two-way satellite network capable of transmitting at up to 32 megabits per second (Mbits/sec), he says. Singley further expects 802.11 devices to reach transmission rates of 22 Mbits/sec.
Singley agrees that potential interference is an issue. Nokia will test its technology with Boeing, Airbus and three regional jet players. But he is confident because "Rockwell and Condor showed no interference." Ground use also is an issue because airplanes, baggage tugs, fuel trucks, even people-movers will be transmitting over wireless LANs. And passengers will want to use the technology at the gate. But the issue can be solved with careful design, engineering and management, he says.
GE Harris Aviation, a joint venture between General Electric and Harris Corp., already offers a terrestrial wireless data communications system called Airline.link, says Jim Ziarno, vice president of marketing and business development.
Airline.link uses IEEE 802.11 and is functionally compatible with the ARINC 763 standard, he says. Condor also is testing Collins’ ground-based wireless LAN in two-way communications applications between the aircraft and the gate.
GE Harris is demonstrating a flight operations quality assurance (FOQA) application with U.S. Airways aboard five Boeing 757s. Comair, a regional carrier owned by Delta Air Lines, has been running an "out-off on-in" (OOOI) reporting application since last fall.
The automated system promises to provide more exact data for scheduling, pay and fuel reporting.