Ryanair CEO Michael O'Leary has criticised the updated travel green list - saying one of the countries on it "doesn't even have an airport".
He's queried whether the Transport Minister Eamon Ryan "expects us all to cycle to Liechtenstein".
Liechtenstein will be a new addition to the list, but the microstate has no airport.
Only three other countries - Cyprus, Finland and Latvia - will remain on the list from Monday.
Germany, Poland, Iceland and Lithuania are being removed from the list - the former three just a week after they were added.
Speaking on The Hard Shoulder, Mr O'Leary said the new list represents "more incredible mismanagement".
He said: "The joke is that two of the four countries don't have any flights from Ireland, and one of them doesn't even have an airport.
"They've taken off the three big countries they added last week - Germany, Lithuania and Poland.
"What's remarkable is each of those have a COVID rate of 27 [per 100,000 or less] at the moment."
He said Ryanair won't refund flights to Germany for next week as the flights will still operate - and he also suggested that people will be safer in Germany than in Ireland.
'Making this stuff up as they go along'
Mr O'Leary claimed that the Government isn't capable of 'running a sweet shop', and that NPHET's record is 'patchy'.
He said: "They wonder why we're threatening to close Cork and Shannon Airport [for the winter] - our customers can't make any bookings.
"[Officials are] making this stuff up as they go along - not just Ryanair, but Aer Lingus and the airline business is being damaged.
"The response to these events should at least be consistent so people can make bookings... there is no medical or scientific basis for removing Lithuania, Poland and Germany from Ireland's green list.
"I presume Eamon Ryan expects us all to cycle to Liechtenstein?"
Currently, only countries with COVID-19 rates of 25 per 100,000 or less are included in the green list, which is being updated weekly.
Ireland is due to move to a new EU 'traffic light' system when it's finalised next month - but Mr O'Leary said we should have moved to the system weeks ago.
He said that his company does support the new approach, as it will reflect the situations in specific regions of countries.
Mr O'Leary also dismissed Dublin's Airport newly-unveiled plans for testing.
DAA is proposing developing a pre-departure COVID-19 test system for high-risk locations which would prove passengers have tested negative for coronavirus before travelling here.
Outbound passengers would also be able to take a pre-departure test before travelling to any countries that require it - saying the tests would be taken less than 72 hours before departure.
However, the Ryanair CEO claimed the plans are 'pie in the sky'.
He said two tests are needed over a seven or ten day period to be effective, and argued that consumers are not going to run that risk or pay for the tests themselves.