The system is used at the Schengen Area’s external borders to collect fingerprint data.
Ryanair's calling on the EU Commission to allow member states continued flexibility when it comes to the Entry/Exit System.
The system, which went fully live in April, is used at Schengen Area external borders and registers fingerprints.
Up until now, border officials were able to revert to passport stamps if queues became too long.
From today, that's no longer an option, and, while the checks don't apply to Irish passport holders, travel experts are warning of longer queues at European airports.
Eoghan Corry, Editor of Travel Extra, says current staffing levels are letting the system down:
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