It is disappointing to hear that the person in question experienced difficulties with an airline website when using the Passport Card.
The Irish Passport Card is valid for travel to 31 countries: all EU Member States, the members of the EEA (Iceland, Liechtenstein, and Norway) and Switzerland.
It is fully compliant with International Civil Aviation Organisation (ICAO) regulations concerning requirements for passports in card format. Over 209,000 passport cards have been issued to date and users have found it to be a highly convenient travel document.
Airport, port and immigration authorities in each of the countries for which the Card is valid for travel should be fully informed in relation to the Irish Passport Card. The Irish authorities have engaged extensively with our international partners in relation to the card and will continue to do so. We have made contact with the airline to inform them of the problems experienced using the Passport Card that are outlined in your question.