Passengers on a Monarch holiday plane flying from Birmingham to Majorca were left "struck with terror" after hearing a pilot's Mayday call - just moments before the plane quickly dropped altitude.
The flight, bound for Palma, then diverted to Limoges, France, as a safety precaution.
Passenger Andrew Taylor told the BBC that he had feared for his family's safety during the ordeal.
Mr Taylor, from Sutton Coldfield, said: "About an hour into the flight I noticed a hissing, blowing noise which I thought was unusual.
"It was then that the pilot came on the tannoy to the cabin, saying 'Mayday, Mayday - emergency descent'."
He said they then felt the aircraft descend "very, very quickly", adding: "The pilot came back on to the tannoy and said, 'we are now at 10,000 feet and the problem has been resolved, but we're contacting the aircraft manufacturer to see what we need to do'.
"We flew for about another 10 minutes but a decision was then made to land immediately."
Another passenger said: "To say we were completely struck with terror - I can't tell you how we felt.
"But no one screamed on the plane - I think we were just struck mute."
In a statement sent to Aol Travel, Monarch confirmed the incident and apologised for any distress it may have caused, saying: "Monarch confirms that flight ZB958 on 24 July, en route from Birmingham to Palma diverted to Limoges, France following a depressurisation of the cabin.
"The Captain, in accordance with standard response to such an event, placed the aircraft into an immediate controlled descent to lower the cabin altitude, and landed the aircraft at the nearest suitable airfield, in this case Limoges.
"Passengers were transferred to a replacement aircraft to complete their journey to Palma.
"It is a requirement for the Captain of an aircraft to declare a "mayday" to air traffic control if such an event occurs in order that priority handling can be established to facilitate a landing without delay.
"This was accomplished and the aircraft landed safely without incident. During the exchange of radio transmissions some passengers may have heard the "mayday" call over the public address system. The Captain's priority throughout was to ensure a safe, prompt and uneventful landing which he achieved.
"Monarch regrets any concern or distress that this may have caused."
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