Innovation: Satellite gives a pilot position

SATELLITE navigation, which shows where an aircraft is in real time, is starting to replace radio systems that require pilots to plot their position on air charts, writes Nuala Moran.

One system, being launched at the Farnborough Air Show this week, picks up information about the plane's position from the Global Positioning System, a network of navigation satellites originally set up for military use by the US Department of Defense.

The information is displayed with the altitude, date and time on a battery-powered A4 screen, moulded to fit the pilot's knee and held in place with a velcro strap. The unit weighs just under two pounds.

Standard aviation charts are now available in digital form on cartridges that plug into the screen. The map is scrolled across the screen as the aircraft moves over it. It charts show roads, railways, cities, rivers, spot heights and other features of the terrain. The charts allow users to select only the features they want displayed. For example, if a pilot wants to see the primary roads and railways, other information can be turned off.

The system comes with a database that holds detailed airport maps. The screen display looks exactly like the paper charts with which pilots are familiar but have the aircraft's position tracking across it.

To be legal, aircraft will still need radio navigation systems - which depends on picking up a signal from a known location and then working out how far the aircraft is from that location, and plotting it on the chart - because satellite navigation is not yet approved by most regulatory authorities, including the UK's Civil Aviation Authority and IATA, the International Air Transport Authority.

Next Direction, the UK distributor for the US manufacturer Magellan, has so far sold 100 units, costing about pounds 1,200 to private helicopter and business jet companies and has shown the system to police forces interested in using it in surveillance helicopters.