When did aircraft stop being called “ships”?

Solution 1:

A fairly high percentage of early "aircraft" were what we still refer to using the word...

airship - a very large aircraft that does not have wings but that has a body filled with gas so that it floats and that is driven through the air by engines

It was quite natural to call them airships because (being lighter than air) they "floated". But the 1937 Hindenburg disaster "shattered public confidence in the giant, passenger-carrying rigid airship and marked the end of the airship era".

There were probably a small number of people who simply weren't attuned to the developing technology and vocabulary, but I don't think airship = airplane (with rigid wings and propeller) ever had any significant currency, even before the term accidentally acquired those seriously negative overtones in 1937.

Solution 2:

I work for Lockheed Martin and build the f35's center wing box and also at my facility we build the c130, wings for the p3, are doing the upgrades for the c5 and have just recently been awarded the contract for f22 mods and the only way we refer to the airplane is by ship so no its not outdated. Every now and then but very seldom I'll hear the term jet used but 98% off the time it's ship. I am currently working on ship # AM/14 which means it's the 14th f35 for the Netherlands. I'm not for sure where the term comes from but i assume it's airship just shortened to ship. Maybe because they use lift and not air or any other kind of gas to stay afloat.