Ryanair pilots were forced to wear oxygen masks as they made an emergency landing in Barcelona today after a fire extinguisher went off in the cockpit . Passengers said the pilot and first officer were unable to breathe without the masks as halon - a liquefied , compressed gas - filled the confined space as the plane flew from London Stansted Airport to Valencia . TV presenter and professional sailor Hannah White said that passengers suspected there was a serious problem , but they did not know the reason for the emergency landing until they arrived at Barcelona-El Prat Airport . Ryanair flight FR8321 was met by fire trucks when it landed at Barcelona-El Prat Airport . Hannah spoke to told MailOnline Travel as she and other passengers sat on the plane while the pilot and co-pilot were checked over by medical staff . She said : ‘ One of the fire extinguishers in the cockpit went off and it ’ s got halon gas , which is very dangerous , and as a result the pilot and first officer couldn ’ t breathe . ' Ryanair described it as a minor fault involving a fire extinguisher and said the flight crew followed standard procedure by putting on their masks . Hannah added : ‘ The oxygen masks deployed [ for the flight crew ] and we dropped down to a very low altitude . ‘ When [ the pilot ] came over the tannoy to talk to us you could hear them breathing through the oxygen masks . Passengers said they were unaware of the reason for the emergency landing but knew it was serious . TV presenter and professional sailor Hannah White tweeted a photo of fire trucks on the tarmac . ‘ The first thing we heard was “ emergency landing ” , said three times by the captain , which indicates a massive issue. ’ Hannah said the announcement didn ’ t send immediate panic through the cabin as the passengers had no idea why flight FR8321 was diverting . She said : ‘ It was clear that something was wrong . I would have to say the whole situation was dealt with amazingly and professionally. ’ One of the flight attendants became anxious and oxygen masks did not deploy for passengers in the cabin , she added . Passengers hailed the crew for their professionalism while the plane diverted to Barcelona . Several passengers tweeted updates while the plane was on the ground and the pilots were checked over . Fire trucks greeted the Boeing 737 when it touched down shortly after 10:15am local time as passengers began to grasp the nature of the emergency . Hannah , 31 , said : ‘ We had very limited information until we were about to land . It was fairly calm on board , I have to say. ’ Once people learned of the reason for the emergency landing they became agitated that they weren ’ t told sooner , she said . ‘ It ’ s hot [ on the plane ] , and people are pretty keen to get off or find out what ’ s going on. ’ The flight crew declared an emergency over southern France and changed their flight path . Hannah , from London , and her coach were travelling to Valencia for a training session as she prepares to attempt to set a new world record for women ’ s speed sailing . After the plane had been on the ground for about 30 minutes , passenger Josh Adler tweeted : ' @ Ryanair it sounds like the faulty equipment has been replaced and you expect us to re-journey soon , thanks again to the pilots and crew . ' A Ryanair spokeswoman said : 'This flight from London Stansted to Valencia diverted to Barcelona due to a minor fault with a cockpit fire extinguisher . 'The aircraft landed normally and was inspected by a Ryanair engineer , who replaced the fire extinguisher and cleared the aircraft to return to service . 'Customers remained on board and this flight has since departed to Valencia . Ryanair apologised sincerely to all customers affected by this diversion and short delay . 'Both pilots followed standard procedures and all crew continued to Valencia . '
Plane was flying from London Stansted Airport to Valencia , Spain . Pilot heard breathing through oxygen mask while making announcement . Plane was met by fire trucks when it landed at Barcelona-El Prat Airport . Pilot and first officer were taken off plane to be checked for injuries . Ryanair said plane departed for Valencia after a brief delay . Hannah described it as a minor fault involving a fire extinguisher .