Back in the 20th century, they said people would not want telephones on airliners; that they did not wish to be contactable while they dozed in comfort or ate a fine meal. How times have changed. In the 21st century, passengers slip on virtual reality glasses and join the crew in the cockpit - or a conference half the world away, thanks to high-bandwidth satellite communications (satcoms).

Aeronautical satcoms were first envisaged by global satellite system operator Inmarsat. The first telephone call using Inmarsat's aeronautical system was made from a Japan Airlines Boeing 747 in October 1987, with full operation from 1990.

More than 2,200 aeronautical satcom terminals are now operational, more than half of those on commercial airliners. About 60 airlines regularly use satcoms. As the number of aircraft using Inmarsat has increased, satcom applications have been added, ranging from passenger telephone and data services to flightdeck voice and data and air traffic services.

Airlines have become increasingly imaginative in their use of satcoms. In the cabin, the next revolution in passenger communications is set to be e-mail. Passenger services have been limited by the slow transfer speeds of current satcoms, but a higher-speed data service is set for 2001. "Faster, true multi-media data rates are envisaged with subsequent generations of satellites," says David Featherstone, head of Inmarsat's aeronautical division.

With the growth in interactive passenger entertainment services, satcoms have found a role in real-time news delivery, and credit card validation for in-flight gambling and shopping. In the 21st century, the higher-speed data service will allow the airliner cabin to become an extension of a passenger's home or office, with the introduction of Internet-based services.

Airlines are also beginning to use satcoms to monitor aircraft performance, improve ground operations and for telemedicine applications. Extensive use of satcom-based services has been held back, however, by high costs and limited bandwidth. Although new low- and medium-Earth orbit satellite systems such as Iridium and ICO promised much for aeronautical communications, including lower costs, their contribution to the aviation industry is unclear due to both companies' financial difficulties.

Many airlines' rationale for outfitting their aircraft with satcoms has been to benefit from the new communications, navigation and surveillance/air traffic management operating environment. Satcoms are a cornerstone of the concept, allowing waypoint reports to be made in oceanic airspace via satellite datalink, and real-time weather reporting.

A sure indicator of the value of satcoms to airlines is the fact that Inmarsat's voice telephony traffic is rising by more than 10% a year and packet data traffic is growing at 35% a year - mostly for airline operational and air traffic management applications.

Source: Flight International