Modern navigation systems, which are found in most of today' s commercial aircraft, are made with low-power circuitry, which is more susceptible to interference than the vacuum-tube circuitry found in older planes  During landing, navigation systems receive radio signals from the airport to guide the plane to the runway  Recently, one plane with low-power circuitry veered off course during landing, its dials dimming, when a passenger turned on a laptop computer
Clearly, modern aircraft navigation systems are being put at risk by the electronic devices that passengers carry on board, such as cassette players and laptop computers
When in use all electronic devices emit electromagnetic radiation, which is known to interfere with circuitry.