Air passengers have been warned they face bills of hundreds of dollars if they fail to switch to their phone's airplane mode while in flight.
One traveller racked up nearly $US300 ($414) of charges on a flight from Ireland to the US with Aer Lingus after he left his mobile on in an overhead compartment. With signal and roaming turned on, the phone connected to the aircraft's in-flight network provided by aviation telecommunications specialist Aeromobile. Provider AT&T said the bill was the result of "antennas installed on the plane that operate outside an unlimited international roaming plan… automatically connect[ing] with phones that are not in flight mode".
Aer Lingus, one of 23 airlines that uses Aeromobile's in-flight connectivity, confirmed that passengers who failed to switch off their phones could be hit by charges but told the Irish Times it was not profiting.
"For safety reasons, before every flight, Aer Lingus cabin crew advise guests to switch their phones to airplane mode," a spokesperson said, adding phones left on "may connect to the in-flight roaming network and the guest will be billed by their home operator for any usage".
Other carriers to offer an in-flight network include Virgin Atlantic, Emirates and Singapore Airlines.
Information on Virgin Atlantic's website says the service is available on all aircraft based at Gatwick and selected planes at Heathrow and Manchester. "The charges are almost the same as they would be if you were roaming from another country," the airline says. "The calls and texts will just be added to your mobile after you've flown."
Emirates says that all usage will be "charged by your service provider in line with international roaming rates".
Aeromobile has been offering the ability to make calls at 36,000 feet since 2008 after approval from the Civil Aviation Authority (CAA). The first official in-flight call took place on an Emirates service between Dubai and Casablanca.
Since, dozens of airlines have signed up to the technology, with Virgin Atlantic launching the service in 2012.
While the technology makes voice calls possible, some airlines do not allow them. In 2014, a spokesperson for Aeromobile said: "In-flight voice calls is an emotive subject. Most airlines choose to operate voice calls, and in nearly six years of operation AeroMobile hasn't had any issues. On some aircraft however you cannot make or receive a call – the airline has made this choice without regulatory or legislative intervention.
"Demand for the 'quiet' services, such as text messaging and data, far outstrips voice calls."
The technology has not been reserved to the long-haul carriers. In 2009, Ryanair offered the service but scrapped it, citing lack of interest.
The real reason you're told to put your mobile in flight mode
Patrick Smith, a US pilot and author of Cockpit Confidential, says the rule is more an exercise in caution.
"Could a device interfere with the flight? It depends on the gadget and how and when that gadget is used," he said.
Taking the example of laptops, Smith says, though an old computer can emit harmful energy, the greater risk they pose is becoming "high-speed projectiles during a sudden deceleration or impact".
But for phones, Smith says: "Can cellular communications really disrupt cockpit equipment? The answer is potentially yes, but in all likelihood no, and airlines and the Federal Aviation Administration (FAA) are merely erring on the better-safe-than-sorry side."
He continues: "Aircraft electronics are designed and shielded with interference in mind. This should mitigate any ill effects, and to date there are no proven cases of a phone adversely affecting the outcome of a flight. But you never know."
The Telegraph, London