On April 2, Air France began offering voice calls on one of its jets on a trial basis, and BMI of Britain and TAP of Portugal plan to do the same.

Although U.S. airlines have shunned the service, Ryanair, Europe’s largest low-cost airline, is so confident mobile phoning will prove popular that it plans to start offering it in June without even bothering with a trial.

With the Air France trial, passengers only learn about the possibility of using their phone once they are on the plane. An announcement refers them to an instruction card in the seat pocket.

They are told to switch off their phones during take-off and landing – and a special icon has been added next to the seatbelt sign to indicate when phones can be turned on.

[...]

The technology being tested by Air France links passenger phones to an onboard network connected to the ground via satellite. OnAir, the supplier, said transmission levels are low enough to avoid affecting the safety of aircraft equipment.

OnAir is an Airbus joint venture based in Geneva and one of two companies that are offering the technology, along with AeroMobile, a British joint venture with the Norwegian telephone company Telenor.

The system being tested by Air France uses an onboard base station in the plane – called a pico cell – which communicates with passengers’ own handsets. Though low power, the pico cell, located in a compartment normally used for hand luggage, creates a network encompassing the cabin of the plane.

The base station routes phone traffic to and from the plane to a satellite which beams down to mobile networks on the ground. Meanwhile the control unit on the plane ensures that mobiles do not connect to any base stations on the ground – as is technically possible when a plane is flying below 10,000 feet.

Source: International Herald Tribune