Before you take off on a flight (or a cruise), you might want to remember to turn off your phone - or at least set it to "airplane" mode. Failure to do so can lead to unpleasant surprises.
Depending on the plane and your device, a phone which hasn't been put in airplane mode could automatically connect to the aircraft's antenna and rack up the charges without you realizing it. This is because some phones will automatically connect to a roaming network - often using satellite, where charges are much higher - as one traveler flying with Aer Lingus recently found out.
He'd left his phone in the overhead bin during a trip to the USA, and netted himself roaming charges amounting to nearly $300. It may not happen often - but it may happen. Turning the phone off or placing it in "airplane" mode eliminates that bash to your wallet; in "airplane" mode, the phone can only connect with the craft's internal WiFi network, rather following the craft's antenna out to a satellite and back.
And the same applies if you're aboard a ship:
In 2016, Mark Stokes from West Yorkshire received a $433 bill from O2 after roaming while on a cross-channel ferry.
Be wary out there.
