Source: Associated Press

Talking on cell phones or using laptops on an airplane could disrupt cockpit operations, especially global positioning devices that are increasingly being used to help land planes safely, according to a new study at Carnegie Mellon University.

Researchers monitoring flights in the Northeast found that several cell phone calls are typically made on commercial flights during takeoff or final approach, two critical flight stages when accidents could occur.

The research at CMU was led by Bill Strauss, an expert in aircraft electromagnetic compatibility at the Naval Air Warfare Center in Patuxent River, Md.

Researchers monitored radio emissions from passengers on three airlines with the support of the Transportation Security Agency. The emissions were tracked using a broadband antenna that was attached to a portable spectrum analyzer in a piece of carry-on luggage.

Granger Morgan, head of Carnegie Mellon's department of engineering and public policy department, said the activity recorded shows that the use of electronic devices should be limited on airplanes.

Morgan said the disruptions are enough to impact a plane's navigation or other systems.

"I think it's fair to say there has never been an accident that you can clearly say was caused by electromagnetic interference," Morgan said.

The study, which received support from the Federal Aviation Administration, is being published in the March issue of the technology journal IEEE Spectrum.

Airline passengers are instructed to turn off all their portable electronic devices during a plane's landing and takeoff. Once a plane has reached 10,000 feet, airlines generally allow passengers to use laptops or game devices.

The FAA bans cell phone use during any part of a flight.

Some airlines, however, permit the use of newer phones in what is called airplane mode, which disconnects the telephone from the wireless network but allows users to access other features of the phone.

The Federal Communications Commission has commissioned a private, independent firm to study in-flight use of cell phones. The results of the study are due by the end of the year.

The researchers at CMU have recommended that the FAA and FCC work together to investigate in-flight use of cell phones. Also, the researchers recommended on-board radio emissions be monitored regularly by flight data recorders.