Could we use 'COULD HAVE' for speculation in the past ?

Question

Could we use 'COULD HAVE' for speculation in the past ? Are the examples below correct?

In the very heart of Europe, Austria is a country which could have been created with activity holidays in mind.

A source involved in the investigation says airline could have broken up at around 35000 feet.

Though the drain was barely 2 feet deep, the water pressure could have pushed him into the reservoir

Answer 1

That usage is correct. In all contexts, the past modal "could have" is speculating about the past.

In your second example, however, I think you are missing the article "the", and I'd recommend using "airplane" or "plane" instead of "airline"