It's understood that the pilots wanted to land at a commercial airport instead
Two fighter jets were scrambled after Aer Lingus pilots initially refused to land at a military base following a hoax bomb threat, a French prosecutor said.
The jets were scrambled, and the Aer Lingus flight EI402 was escorted to Évreux base.
On Thursday, passengers on the flight heading to Rome described seeing the fighter jets outside the window as "terrifying".
An investigation into the incident has been launched, and both pilots have been questioned.
Rémi Coutin, who is the public prosecutor for Évreux, said both the pilot and co-pilot are allowed to leave France after they were quizzed.
Mr Coutin said the investigation into the matter was ongoing.
In a statement to the Irish Times, he said he launched a probe after being "informed that the pilot of the aircraft had initially refused to comply with the French authorities’ request to land at Évreux, and that two fighter jets had to be dispatched to compel him to do so."
The Aer Lingus flight was one of several that were subjected to bomb hoaxes in recent days.
The airline said: "The captain and crew on Aer Lingus flight EI402 acted impeccably and were thoroughly professional throughout yesterday’s security issue.
"Safety and the care of our passengers is Aer Lingus’ top priority and this was upheld professionally by the captain and crew of the aircraft throughout in what were very challenging circumstances."
Meanwhile, the Irish Airline Pilots Association said questioning is "generally standard procedure".
They said the pilots cooperated fully with the French authorities and are being represented in France by IALPA’s sister union, the SNPL.
IALPA President, Captain Daniel Langan said: "IALPA is fully satisfied that the pilots discharged their legal and safety responsibilities to the fullest extent and acted professionally throughout.
"The primary responsibility of pilots is, first and foremost, the safety of their passengers, crew and aircraft. Pilots have clear legal responsibilities and authority in relation to the safe operation of their aircraft. In the case of an Irish-registered aircraft, these responsibilities and powers are governed by applicable Irish law, as well as the relevant laws of the state in whose airspace the aircraft is operating."
He went on to say: "IALPA fully supports the pilots involved and is satisfied that their actions were consistent with their professional obligations and their overriding responsibility for aviation safety.
"IALPA will continue to liaise with the relevant parties to ensure that the pilots are fully supported and can return home safely today."
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