In a holding pattern 13,000 feet somewhere above the southeastern United States, the pilot saw the guidance computers and the controls that maintain the craft’s lateral stability shut down. A passenger in row 1–directly above the flight computers and near the navigation antennas–was using a radio transmitter and receiver, a flight attendant said. The first officer hurried back and told the man to shut it off, the systems blinked back on. Five years later, no one can explain how, or even if, the radio zapped the computers.
The friendly skies have become the spooky skies. Since 1990, the Federal Aviation Administration, airlines and airplane manufacturers have heard nearly 100 reports of mysterious electronic interference with planes’ communications and navigation systems. Planes have strayed off course and lost vital flight information displays; cockpit screens showing fuel availability and wind speed have gone haywire. But that’s not the worrisome part. Even more troubling than the incidents–none of which led to crashes–is that they’ve stumped the brightest engineers, from Boeing to Apple to NASA. In response, major carriers–including American, Delta, Northwest, United and USAir–have restricted the use of carry-on electronics, especially below 10,000 feet, where the risk of a crash is greatest. Absent an explanation for the interference, insists Anthony Broderick of the FAA, there is “no technical basis” for believing CD players, laptop computers, camcorders, handheld electronic games or other electronic gizmos foul up an airplane’s communication and navigation systems. That attitude annoys the airlines. With six times more reports of electronic mishaps this year than last, the carriers say two miles up is no place for mysteries of any but the paperback kind.
There’s no question why airplanes are fat targets for electronic mayhem. They’ve become computers with wings. Silicon chips collect, interpret and display data on engine temperature and fuel use; they conduct the preflight checkout and allow planes to find runways in zero visibility. The 747-400, Boeing’s most modern bird, has 145 miles of wire stuffed under its skin to connect computers to aircraft systems. At last month’s Paris Air Show, manufacturers displayed sleek new planes in which electronic signals, not hydraulics, fink the cockpit to the flaps, landing gear and attitude and elevation controls.
To sort through the ways CD players and laptops might send stray signals into this electronic labyrinth, Boeing last December assembled an electronics SWAT team. At the same time, the Radio Technical Commission for Aeronautics (RTCA), an independent aviation group, reopened a 1988 investigation that called interference from passenger electronics unlikely. Early word is that the new study group, which includes scientists from the air force, Delta Air Lines, Sony and IBM, Will substantially revise that conclusion. Among the gremlins RTCA and Boeing are investigating:
The low frequencies and tiny voltages of the suspect devices make it unlikely they could scramble a plane’s electronics. But when a laptop is repaired, the shielding that keeps radiation from leaking might crinkle so as to focus the radiation and make it more of a threat. “I don’t know if the serviceman [makes sure] he hasn’t messed up the shielding,” says Boeing engineer Jim Boone.
An electronic gadget might emit a frequency matching that in a plane’s computers. Then, like pushing a child’s swing at the same frequency with which it naturally goes back and forth, the pulses from the CD player might amplify the computer’s internal signals catastrophically.
From some seats, escaping electromagnetic radiation may reflect off surfaces and bounce toward sensitive electronics. A laptop in a wing seat might send radiation out the windows and up the skin of the craft, to antennas atop the fuselage. Although other equipment is shielded against electromagnetic rays, antennas seek them out. Signals from a laptop or CD player could be confused with the locator signals from ground stations.
Airlines and the FAA insist the mysterious electronic glitches pose no safety threat. Some cabin crews don’t even take the problem seriously enough to enforce the ban on using CD players and laptops on takeoff and landing. On two flights on different carriers this month, a NEWSWEEK reporter found, none of the crew batted an eye when he listened to his CD player as the plane rolled down the runway.
