Have you tried building the query 1 Lego at a time? By this I mean, drag in the first table, the one that you consider the most prominent in the query.

In your first image, that would be CountryT. Then bring in just one other table and set the join, and see if you get data. If you do, then add the third and check again.

Secondly, you have the current joins:
CountryT.CountryID inner join to CityT.CountryID
CityT.CountryID inner join to AirportT.CountryID

I might try:
CountryT.CountryID inner or left joint to CityT.CountryID
CityT.CityID inner or left join to AirportT.CityID

Since the country in the airport table should match the country in the city table, that will get picked up with the city join and Access won't get confused on which country id it is matching.

Well, it doesn't really tell us what you're trying to do by just showing us the screenshot of the query design. Tell us in English what you're trying to accomplish. Is it that multiple airports can be in a city? Is that what you're trying to show? For example, here in Fort Myers, we've got Southwest Florida International and we've got Page Field. Is that what you're trying to represent?