using USB ports on internation flights
 

My last flight from Dublin to Philadephia was on an AA plane with a USB port in the armrest but no regular or cigarette lighter type sockets. Anyone know how these USB ports be used to charge a notebook computer or are they only for smart phones and pads? Thanks, FG

Generally, there is not sufficient power to charge anything. Those ports will run a device, but not charge it. That's perfect if you've got your device fully charged when boarding. Not so great if you've run the device down enroute to your flight.

USB typically puts out 500mA to 1A at 5V, or 2.5-5W. Laptop chargers are typically in the 50-70W range or greater (4A at 15V for the one next to me right now). A USB port could charge your phone, maybe a tablet, certainly not a notebook/laptop.

ime theyre very very unreliable. bring your own powerpack if it is a concern.

USB ports are basically only useful for maintaining a charge on a phone, or maybe for charging slowly with the phone off. Just make sure your phone is set up to be charging and not transferring, as it won't take as much juice if in mixed mode.

They are useless for a laptop.

I'll echo what's been said above, those USB ports cannot power a laptop much less charge one in use.

However I will say that some airlines have USB ports which supply sufficient power to charge a phone in use and charges phones at a rate comparable to terrestrial power sources (not including those phones that use 2A chargers for supercharging). The ones I used on the last few Delta LH flights certainly seemed well powered.