Experience shows us that transmission becomes widespread within the passenger cabin involving all sections when the ventilation system is not working -- as evidenced by an influenza outbreak in 1979 involving passengers being kept aboard grounded aircraft with an inoperative ventilation system.

CNN: Commentary: Flu and your health on a plane

Both Mr Obama and Mr Kenny hailed airline Ryanair's announcement on Tuesday that it will buy 175 jets from Chicago-based Boeing Co, which has struggled ever since its new 787 Dreamliner was grounded by regulators in January following problems with its electrical system.

BBC: Peter Robinson and Martin McGuinness meet Barack Obama