It’s always a good idea to charge your cellphone before flying, if for no other reason than so you can play Angry Birds while sitting at the gate or during the flight.
Now there is another reason to do so.
The Transportation Security Administration has decreed that fliers heading to the United States may be required to power on their cellphones and small electronics to prove they aren’t actually cleverly disguised explosives.
For now, the rule applies only to flights from “certain overseas airports,” but given the fact that messages often get crossed, it’s probably a good idea to have that cellphone ready to power on at domestic airports, too. It will be interesting to see the impact of the rule — whether it leads to longer lines at security, and if the rule gets expanded to domestic flights.
It’s the latest in a string of changes related to small electronics and flying. The big positive change is that such devices can now be used during takeoff and landing (as long as they are in airplane mode).
The other important rule, though only sporadically enforced, relates to how the batteries that power these devices (and laptops) are to be transported due to risk of fire. Lithium batteries that are being used outside of a device need to go in carry-on rather than checked luggage.
This article originally appeared on Recode.net.