<P> A NASA publication details the fifty most recent reports to the Aviation Safety Reporting System (ASRS) regarding "avionics problems that may result from the influence of passenger electronic devices ." The nature of these reports varies widely . Some merely describe passengers' interactions with flight crews when asked to stop using an electronic device . Other reports amount to crews reporting an anomaly experienced at the same time a passenger was witnessed using a mobile phone . A few reports state that interference to aircraft systems was observed to appear and disappear as that particular suspect device was turned on and off . One entry in the ASRS, designated ACN: 440557, reports a clear link where a passenger's DVD player induced a 30 - degree error in the display of the aircraft's heading, each time the player was switched on . However, this report dates back to 1999 and involves a Boeing 727, an old type of aircraft that is no longer in use by airlines today . </P> <P> A 2003 study involved three months of testing with RF spectrum analyzers and other instruments aboard regular commercial flights, and one passage reads: </P> <P>... our research has found that these items can interrupt the normal operation of key cockpit instruments, especially Global Positioning System (GPS) receivers, which are increasingly vital to safe landings . Two different studies by NASA further support the idea that passengers' electronic devices dangerously produce interference in a way that reduces the safety margins for critical avionics systems . </P> <P> There is no smoking gun to this story: there is no definitive instance of an air accident known to have been caused by a passenger's use of an electronic device . Nonetheless, although it is impossible to say that such use has contributed to air accidents in the past, the data also make it impossible to rule it out completely . More importantly, the data support a conclusion that continued use of portable RF - emitting devices such as cell phones will, in all likelihood, someday cause an accident by interfering with critical cockpit instruments such as GPS receivers . This much is certain: there exists a greater potential for problems than was previously believed . </P>

Why should cellphones be turned off in planes