(After all, I’ve secretly turned it on till the last minute before take-off, and switched it on first thing after touchdown. And nothing really happened.)
Well, you got lucky, and thank God for that. The fact is, electronic devices can be dangerous during flights. A report by the International Air Transport Association documents 75 separate incidents of possible electronic interference linked to mobile phones and other electronic devices.
In one case, this is what pilots reported: “Auto pilot was engaged. At about 4500 ft, the autopilot disengaged by itself and the associated warnings/indications came on. Flight attendants were immediately advised to look out for passengers operating electronic devices. They found one handphone and three iPods to be on. The crew made an urgent announcement, requesting passengers to switch off their devices. After this, the plane proceeded “without any further incident.” (Source: Independent Traveler)
So, don’t turn up your nose at the request to switch off. Press your finger down on the ‘Off’ button instead.