(CNN) --Scandinavian Airlines (SAS) has joined the growing number of operators using iris scanning as an electronic means of accessing flights.
Some 80 of its frequent flyers are acting as guinea pigs to test the new system at Umea Airport in northern Sweden.
On arrival at the airport, passengers are instructed to place a smart card near an electronic reader, and look into a camera.
A picture of the iris, the colored ring of tissue in the eye, is taken and if it matches the data on a passenger's smart card the turnstile will let him through.
Frankfurt airport -- Germany's biggest -- and Amsterdam's Schiphol airport are also testing iris-scan machines for passenger use.
In the U.K., the Home Office plans to install iris recognition immigration systems -- known as IRIS -- at 10 sites across the country, following a successful trial at Heathrow.
"Assuming the test project is a success, the trigger would be that some airport authorities start demanding ID checks for all passengers at the gate," Charlotte Rosengren-Edgren from SAS told CNN.
"As an airline we are just users, not owners, of the infrastructure at the airports. The interest and involvement from airport authorities is vital."
Seventy-five percent of SAS passengers already use a ticketless, fully automated system to book flights and check-in.
Passenger identity checks are seen as the next stage to be automated by some in the industry, although doubts persist over the reliability and integrity of biometric databases.
"This simple automated way of going through the airport would not work if we needed to ID control all passengers, but it could be a good choice for frequent flyers," explains Rosengren-Edgren.
Schiphol airport is also in the process of introducing face-scanning systems that operate faster than an iris scanner, analyzing passengers as they pass by.
The machines measure intricate personal details, such as the distance between the eyes, thickness of lips and even the angle of the nose.
Airport biometric testing comes ahead of expected proposals in the coming months by the European Commission on integrating bio-data in European Union passports.
The United States has already stipulated that all passports issued after October 26 in visa waiver countries must have biometric indicators in them.