Aer Arann has taken legal proceedings against a Polish company alleging that two crewed aircraft provided by the company were defective and that the pilots' flying raised serious safety concerns.
The planes had been leased by Aer Arann under a charter agreement from White Eagle Aviation, (WEA) of Woloska Street, Warsaw, Poland.
The two aircraft have been grounded at Dublin airport since last Saturday when Aer Arann obtained an interim injunction from the High Court preventing WEA from removing the aircraft.
Aer Arann claims WEA has breached a contract to operate the aircraft in a safe and effective manner and in accordance with rules and regulations governing air travel.
In one incident, Aer Arann alleges a pilot in one of the aircraft went 10 miles wrong when proposing to land in Galway and, in another case, claims a plane had to be diverted to Kerry airport.
Last Wednesday Mr Justice Roderick Murphy continued the injunction pending the outcome of proceedings by Aer Arann.
An affidavit by Aer Arann's solicitor said the airline became aware earlier this month there had been "a number of potentially serious breaches of safety" by WEA.