A growing number of high speed rail links to airports are available for booking on the GDS.
The Heathrow Express in London and the Arlanda Express in Stockholm can already be booked through Amadeus, one of the leading GDSs.
Three other air/rail links to Gatwick, Vienna and Kuala Lumpur Airports from their respective cities are due to be added next.
A link to the GDS enables travellers to book rail tickets at the same time as their reserve their air tickets.
This move to integrated ticketing was the theme of the AirRail 2008 conference held at Gatwick yesterday (October 29).
Delegates heard that previously rail links could only be booked through operators' websites.
Philip Martin, senior manager marketing of Amadeus Rail, said: "We are looking to ensure access to the GDS is as cost-effective as possible for rail operators. This will help them win more inbound passengers."
Amadeus has also integrated air and Eurostar bookings from London to Paris/Brussels, and shows some German and Swedish rail routes on the same display as flights.
Heathrow Express - celebrating its 10th anniversary this year - is also one of the first rail operators to introduce mobile phone ticketing.
A bar-coded plain paper ticket can be printed at home or in the office, and now a bar-coded e-ticket can be sent to a mobile phone to be read by the ticket inspector's hand-held device.
Airlines are also working on bar-coded boarding passes to be sent to mobiles, but take-up of this technology can be slow.
Most Heathrow Express passengers booking in advance still prefer to print a paper ticket, delegates heard.
The EC has started a consultation exercise on air-rail ticketing and hopes to see it more widely adopted throughout Europe.
The conference was organised by the International Air Rail Organisation, which lists airport rail links worldwide on its website.
www.airportrailwaysoftheworld.com