Imagine - instead of a piece of card that always finds its way to the bottom of your bag, and is also very easy to leave at home, you'll soon be able to check onto a flight using your mobile phone.

American Airlines is trialling mobile boarding passes for domestic passengers travelling out of certain US airports.

The airline hopes that if this technology works, it will not only cut down on paper waste, but also make it quicker and easier for flyers to check in.

What will be sent to the passenger's mobile phone from the American Airlines' website will be a two-dimensional barcode.

Passengers just have to check in online - whether from their computer or phone - and then they will be sent a link to their virtual boarding pass, which can then be scanned from the phone screen before they go through security.

The system is being trialled first at Chicago's O'Hare airport, and will be available at Los Angeles International and John Wayne Orange County airports from 17 November.

And more airports are to follow.

American Airlines is following in the footsteps of Continental Airlines which rolled out mobile boarding passes late last year in seven airports, and Delta Airlines carried out its own test earlier this year at New York's LaGuardia airport.