Aircraft passengers should be able to use their own cellphones in flight safely and conveniently before the end of this year through a new service developed jointly by satellite operator Inmarsat, aircraft communication systems specialist Arinc and mobile telephone service provider Telenor. According to the partners, the system will cost no more than $100,000 to install on each aircraft and users will pay around $3.50 per minute to make calls and about $1 to send text messages.

This will represent a substantial saving to consumers who are currently paying between $8 and $10 per minute for existing satellite phone services. Inmarsat marketing director Robert Johnson is confident that in-flight cellphone services will prove hugely popular with passengers who have become disenchanted with what he describes as expensive and inconvenient satellite phones.

Initially, the service will be limited to users of GSM technology, which accounts for almost three-quarters of all cellphones worldwide. According to research by Inmarsat, around one billion cellphone customers will be able to use the system from its launch. Later, Inmarsat, Arinc and Telenor intend to extend the service to other cellphone technologies, such as CDMA, which is in widespread use in the U.S.

According to Frank Genin, chief executive of independent communications solutions provider Jetlab International (see related story on page 52), in-flight cellphone service will render satellite phones obsolete. “We don’t expect to see anyone installing them from now on,” he told AIN, adding that he expects to see operators of business aircraft as the first to install the pico cell systems.

The service is currently being developed under the working title Arinc/Telenor Mobile Connectivity but is due to be unveiled with a distinct brand name during the first quarter of this year. The partners are working with international aviation authorities to complete certification of the system, for which they have to demonstrate that cellphone signals will not interfere with aircraft avionics even if the equipment fails. Over the next few months they hope to test the system in flight and to complete certification by around the middle of this year.

According to Genin, the service has cleared about 70 percent of the regulatory hurdles, but there remain some significant issues, such as the different power ratings of various cellphone models. Jetlab estimates that it may take until the fourth quarter of this year to resolve all of these points.

Routing Calls
Like the rival OnAir system being developed by Airbus, Tenzing and Sita, Mobile Connectivity uses pico cells to create a mini mobile cell in the aircraft cabin. These cells replicate the ground-based GSM network and translate the GSM voice call into a format that can be sent to ground stations via the relatively narrow band of the aircraft’s satcom system. From the ground stations, the calls can be relayed via whichever cellphone roaming service the customer subscribes to.

Customers pay for their calls through their regular cellphone service provider, eliminating the need to register credit cards or account details. In addition to its own cellphone network, Norway-based Telenor already has some 220 roaming agreements with other service providers around the world. Airlines and other commercial aircraft operators will receive a commission on calls made, allowing them to recoup installation costs and generate some additional income. Any incoming voice calls or text messages will be billed to the sender and recipient on whatever basis their respective service providers already use.

Crucially, the pico cells–which weigh about 30 pounds per shipset– prevent cellphones from transmitting at power levels that could interfere with avionics systems. They need transmit at only one milliwatt, one-tenth of the current limit for certification. Cellphones on the ground can transmit at power ratings as high as one watt.

As an additional safety measure, Arinc is introducing electronic shielding through a noise floor lifter being developed with the UK’s Roke Manor Research. This also prevents cellphones from transmitting at high power levels and will guard against any cellphone that is searching for a ground-based signal, including non-GSM types such as the CDMA phones. Airlines are well aware that a significant number of passengers are still leaving their cellphones on during flights–usually unintentionally–and that this constitutes a safety risk. So Arinc’s case to the regulators is essentially that the new system will provide a greater level of safety than exists with the current ban on all cellphone use.

At least 3,000 aircraft worldwide currently fitted with Inmarsat’s Aero-I satellite commu- nications systems could quickly fit the pico cell system. The equipment also needs software to handle the routing of calls through a server. Subject to there being sufficient capacity, most operators will be able to use existing Linux-based servers that manage existing satellite communications equipment and in-flight entertainment systems.

According to David Coiley, Arinc’s director of air ground services, cellphone use will generally be permitted only during cruise phases of flight. Aircrew will be able to disengage the pico cells by flipping a switch, and airline crews might choose to do this during overnight flights so as not to cause annoyance to passengers trying to sleep.

In addition, the crews can adjust the system so that passengers can use cellphones for sending and receiving text messages only. The fact that the system can be disengaged is one of the reasons that the noise floor lifter shielding system is needed to prevent cellphones from transmitting at high power levels when the pico cells are switched off.

Though the partners are initially aiming marketing efforts for Mobile Connectivity at the airline sector, they believe they are close to signing the first business aircraft operator to help test the service. Fractional-ownership provider NetJets is also interested in the system.

Arinc is now in discussion with airframers with a view to offering the cellphone systems as optional equipment on new aircraft. The company is also in discussion with service and modification centers to handle retrofit installations. It can also provide these through its Arinc Engineering Services subsidiary in Colorado Springs, Colo.

Meanwhile, the rival OnAir in-flight cellphone system had its first flight tests in September last year on board an aircraft provided by Airbus. The partners behind this program feel that certification and regulatory issues will take longer to resolve and their target date for service introduction remains the second quarter of next year. At the same time, the companies are still waiting for European Commission anti-trust approval and now expect to be able to incorporate their joint venture next month.

According to a spokesperson, OnAir’s call charges will be in line with international roaming rates for cellphone services on the ground, but, unlike Inmarsat and its associates, the partners have yet to provide specific estimates or announce details of commercial arrangements with cellphone service providers. They have also yet to provide details of installation costs for aircraft operators.