Seem's like the TSA (Transport Security Administration) has decided to give travellers one more thing to worry about as they struggle to put back their shoes, belts and store their notebooks. Passengers flying to the US will need to turn on ther smartphones as part of the long line of checkpoint rituals they already have to endure in the name of safety and security.
The latest rule states that, "Powerless devices will not be permitted onboard the aircraft," this means screeners may now ask travellers to turn on those devices as part of the process. "The traveller may also undergo additional screening," the TSA added. Should a phone or tablet not turn on or be deemed to have low battery power, it might result in confiscation of the phone or tablet. It might be a good idea to invest in an external charger to keep everything juiced pre-flight.
Source: Politico