Passengers on the Aer Lingus flight from Dublin to Paris began shouting out and crying as they thought their plane was about to ditch.
The drama followed an initial announcement made in English, telling passengers to return to their seats because of turbulence.
Aer Lingus said the mistake was down to a mechanical failure.
But then the crew accidentally played out a recorded emergency landing warning in French as the plane headed south over the Irish Sea.
Around 70 French passengers were reported to be “freaked out” on hearing the warning.
One English-speaking passenger said: “The French man sleeping next to me woke up and looked very startled.
I got quite alarmed. The woman behind me was crying. All the French totally freaked out.
An English-speaking passenger aboard the flight “He then translated what had been said, that the plane was about to make an emergency landing and to await instructions from the pilot.
“I got quite alarmed. The woman behind me was crying. All the French totally freaked out.”
The plane was just 20 minutes into its flight to Paris when the bungled announcement was broadcast.
The Irish airline’s cabin crew quickly realised their mistake and swiftly apologised in French.
An airline spokesman said: “There was a malfunction of the public address system and we apologise to our passengers.
“This sort of thing happens very rarely.”