Around 60 ramp control staff working for the Aviance company stopped work at Dublin Airport this morning.
It is understood the unofficial industrial action was taken in support of one member of staff over a specific issue.
Other staff are operating the ramps to ensure baggage makes it onto planes.
Aer Rianta says there have been no delays so far to the flights with airlines that use Aviance for passenger and baggage processing at the airport.
Aviance provides ground-handling support to airlines such as Lufthansa, British Midlands, ARN and SAS.
Informal discussions are taking place to try to avoid any delays occurring with arrivals and departures later in the afternoon.
Aviance staff are normally represented by SIPTU and the ATGWU.
