The defendants appearing in a court in the Lower Austrian town of Korneuburg are thought to have smuggled 25 people onto planes while working for a private security firm at Vienna International Airport.
According to the prosecution, the four accused - who come from Sri Lanka, Poland and Austria - are part of a wider criminal network of smugglers. They are thought to have charged each person €9,000 to be smuggled onto the plane.
Since they were caught last year, the airport has introduced new biometric checks to get into the security area.
They are thought to have been working for the UK company G4S, a firm hired to carry out additional security checks for Austrian Airlines.
They allegedly carried out the scheme by asking friends to pass through the security checks with flight tickets that were then handed over to the smuggled people who had been sneaked in and were waiting in the airport toilets.
“The last passport control at the gate is also carried out by the private security service for our airline,” explained spokesperson for Austrian Airlines Sandra Bijelic last year, when the scheme was uncovered.
The investigation was triggered after one of the people who bypassed security was refused entry by US authorities.
A G4S spokesperson confirmed last year that an employee responsible for checking visa documentation at the airport on a contract with Austrian Airlines was dismissed in March following his arrest.