I was on a domestic Indigo flight in India 6E378 (Bangalore to Kolkata), and was trying to use my iPhone 4S in Airplane mode after takeoff. The cabin crew asked me to turnoff the phone completely and not even use in Airplane mode even after takeoff, she told this is rule from Airbus and she has an email from Airbus authority clarifying this. As per her and Indigo Airlines no smart phone can be used in Flight Mode/ Airplane mode through out the flight time as it still transmit cellular signal and interfare in flight operation ---- Anyone here can clarify please