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The communications-free bubble of air travel will be punctured next month by technology giving passengers access to broadband internet at their seats.

German carrier Lufthansa will be the first commercial airline to offer its customers the chance to send and receive e-mails and surf the web via their laptops, using a system called Connexion, developed by Boeing.

Connexion – the result of more than five years of intensive R&D activity – uses a two-way satellite link and a network of ground-based systems to receive data at up to 20Mb/s, comparable to domestic broadband. It also enables satellite TV to be broadcast inside the cabin, marking the end of the often dreadful in-flight movie.

Business passengers are expected to be the first users, but the technology is likely to eventually be offered throughout the plane.

Boeing had to overcome significant commercial and technical obstacles to get Connexion to this stage. Roll-out was delayed for several years by the impact September 11 had on the finances of the world’s airlines, which viewed projects such as Connexion as non-essential luxuries until they got back on their feet.

Technical hurdles included maintaining a reliable satellite link when flying at 35,000ft at 500mph without resorting to expensive military-style technology. The key to this is an antenna custom-developed for Connexion by Boeing and Mitsubishi. The computing hardware needed to support the system also had to meet the strenuous space and weight restrictions of a commercial airliner.

The delay in launching Connexion may have worked in Boeing’s favour, as it coincided with the emergence of 802.11 wireless networking technology, or wi-fi. This was a godsend for Connexion, as it allowed passenger cabins to be networked without additional wiring to each seat.

While the ban on using electronic devices during take-off and landing will remain, Boeing said it had tested Connexion in conjunction with relevant national air safety bodies to ensure that it did not interfere with flight instruments.

Scandinavian airline SAS and Japan Airlines will follow Lufthansa in offering the service. BA has also tested it and is considering whether to adopt the system. Pricing will depend on individual airlines, but is likely to be about £15 for unlimited access throughout a flight, or a reduced rate for 30 minutes online.

SAS’s decision to adopt Connexion is particularly sweet for Boeing, because its fleet consists of aircraft built by arch-rival Airbus. Connexion was designed to be manufacturer-neutral. Airbus is involved in its own Tenzing initiative, which uses an aircraft’s existing communications systems to allow passengers to send and receive simple text-based messages via e-mail or SMS.

While Tenzing is cheaper and avoids the need to retrofit equipment such as the antenna to aircraft, it operates at far lower bandwidths than Connexion and as a result is highly limited.

Boeing is counting on the fact that web-surfing air passengers will settle for nothing less than they are used to on the ground.

Sidebar: The key to Connexion

Connexion relies on maintaining an uninterrupted link to a global network of satellites that send and receive data on the high frequency, high quality Ku-band.

The service must maintain the link regardless of aircraft speed, weather conditions, changes in altitude and be able to swap satellites without its web-browsing passengers even noticing.

The key to all the above is the antenna, which must offer this high level of performance and also be light and low-profile enough not to create excess drag on the aircraft.

Such technology does exist, but mainly on money-is-no-object military programmes.

When it began developing Connexion Boeing used twin phased-array antennas, one for transmission and one for reception.

Phased-array antenna systems are electronics based and highly efficient at switching between satellites. It was clear, however, that they were too expensive for mass retrofitting to a commercial fleet if the airline hoped to make money from the service.

Working with Boeing, Mitsubishi Electric designed a low-profile reflector antenna that uses less costly mechanically-steered satellite tracking technology.

The elliptically-shaped antenna uses custom-developed systems including new power transmission and velocity detectors and a high-precision polarisation controller to deliver the necessary accuracy.

The Mitsubishi antenna acts as transmitter and receiver from a single unit, lowering costs and weight further and keeping external protrusions to a minimum.

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