No matter what theories one can produce or what anyone thinks is safe, under FARs and JARs it is an offence for anyone to use or permit to be used, any device that intentionally emits electromagnetic radiation in an aircraft, at any time, unless the device has been proven not to cause interference with the aircraft systems. The regulations don't say how much radiation or what frequency, they categorically cover ALL transmitting devices that haven't been specifically tested. There are perfectly good reasons for the rules, based on testing carried out by the RTCA on behalf of ICAO and the FAA.
The laptops used on Lufthansa's Connexion demonstration flights were all tested and found not to affect the aircraft systems. LH propose to lend PCs to people who wish to use the service. Eventually control standards will be introduced to permit general use of Wi-Fi equipment on aircraft. Until then it remains unlawful to use any transmitting device unless it has been proven not to interfere with the aircraft systems. Bring your certificate.
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Through difficulties to the cinema