There seems to be no evidence to suggest that turning off electronic devices helps:
“The fact is, the radio frequencies that are assigned for aviation use are separate from commercial use,” Mr. Altschul said. “Plus, the wiring and instruments for aircraft are shielded to protect them from interference from commercial wireless devices.”
Surely if electronic gadgets could bring down an airplane, you can be sure that the Department of Homeland Security and the Transportation Security Administration, which has a consuming fear of 3.5 ounces of hand lotion and gel shoe inserts, wouldn’t allow passengers to board a plane with aniPad or Kindle, for fear that they would be used by terrorists.
I like this nugget:
The government might be causing more unnecessary interference on planes by asking people to shut their devices down for take-off and landing and then giving them permission to restart all at the same time. According to electrical engineers, when the electronic device starts, electric current passes through every part of the gadget, including GPS, Wi-Fi, cellular radio and microprocessor.
It’s the equivalent of waking someone up with a dozen people yelling into bullhorns.