WASHINGTON, US - THREE United States airlines are permitting passengers to check in to domestic flights using cellphones or other web-enabled devices, the Transportation Security Administration said.

Delta Air Lines domestic passengers departing out of New York's La Guardia airport may use a paperless check-in system that would have them download a boarding pass with a bar code to their phone or device that would be scanned by TSA at security checkpoints and upon boarding the plane.

US carrier Continental launched a similar system in November 2007 at four US airports including Newark. Northwest debuted its paperless boarding system in May out of the Indianapolis airport in Indiana.

'Passengers can now quickly check in for their flight while en route to the airport in a taxi or walking from the parking lot to the terminal,' Delta executive vice-president of operations Steve Gorman said in a statement on Tuesday.

'The check-in process now can take place from anywhere, any time within 24 hours of flight departure.' In Europe, Air France and KLM have proposed the service for flights between Paris and Amsterdam.

The on-the-fly service is the latest innovation introduced by TSA to accelerate security procedures at America's airports.

Since Feb 21 airports including New York's JFK and La Guardia have proposed colour-coded check-in for 'families' (green), 'normal' (blue) and 'expert' (black) - the 'experts' being those who need the least time to remove their shoes and belts to go through security.

In 2005, the government partnered with private enterprise to launch a pay programme which allows faster trips through security checkpoints.

The CLEAR card, for example, contains a traveller's personal information including fingerprints and an image of the iris.

Available at 18 American airports at a cost of US$128 (S$175) each and validated by US authorities, the card guarantees a five-minute trip through security. -- AFP