I fly a couple times a year between Italy and Spain with Ryan Air and my national issued ID card is OK. From Ryan Air site: https://www.ryanair.com/gb/en/usefu

I fly a couple times a year between Italy and Spain with Ryan Air and my national issued ID card is OK. From Ryan Air site: https://www.ryanair.com/gb/en/useful-info/help-centre/terms-and-conditions#section-termsandconditionsar_368204930-termsandconditionsse_579117795 https://www.ryanair.com/gb/en/useful-info/help-centre/terms-... >INTERNATIONAL TRAVEL - TRAVEL DOCUMENTS ACCEPTED : A valid passport (Note: all non EU passport holders, travelling into a Schengen member country are obliged to ensure that their passport is valid for at least 3 months from the date of their departure from the Schengen member country. This requirement does not apply to holders of a Schengen issued residence permit or long term visas). A valid National Identity Card issued by the government of a European Economic Area (EEA) country. (Only the following EEA countries currently issue National Identity Cards acceptable for carriage on Ryanair flights: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Estonia, Finland, France, Germany, Gibraltar, Greece, Hungary, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Netherlands, Malta, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland. The validity of French National ID cards (issued for adults) has been extended from 10 years to 15 years ONLY for cards issued between 2nd January 2004 and 31st December 2013. ... The request for passport probably derives from the UK seemingly not issuing a suitable national ID card.