All of the 500-800 passengers aboard a B747 or A380 certainly won't all have their cellphones, laptops, tablets, and other devices completely shut. Ever. Some f

All of the 500-800 passengers aboard a B747 or A380 certainly won't all have their cellphones, laptops, tablets, and other devices completely shut. Ever. Some forget it, some don't pay attention, some deliberately leave theirs on. In the average, there are always few devices on. Multiply that by a few hundred takeoffs and landing on a single busy airport. No planes have crashed so far because of that. IIRC, some aerospace manufacturers have stated that they would allow electronic devices being on if only <insert your local aviation control body here> approved. I much more gladly believe the cell tower explanation than any appeal to security.