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.