160 controllers have written to the regulator.
The Irish Aviation Authority has denied there's an increased risk of an accident, because of a reliance on air traffic controllers doing overtime.
The Sunday Independent reports 160 controllers have written to the regulator, claiming staffing arrangements have become a safety issue -- which narrowly threatened to close Dublin Airport last month.
The IAA says it's aware of the letter, calling it "an unofficial action by a small number of staff".
It says safety has never been "compromised" and there has been "no risk to air traffic control services in the last year".