I'll be honest and say that I'm not completely sure how tilting windows hurt and kill cats but they do. I'll have a guess at how it happens. A cat uses the window as a means to go outside and come back inside. On returning the cat jumps onto the window and it swings upwards and the cat ends up near the edge of the window where she becomes trapped between the tilting window and the window frame.
The reason why a cat might jump onto the window itself rather than the windowsill is because a tilting window can be in a horizontal position and provide a flat surface. A cat will not realise that this flat surface is not solid. Instead it is like a seesaw. When the cat jumps onto the flat surface the window rapidly swings upwards at one end and somehow the cat finds herself at the edge of the window at which point the window PVC edge of the window slams down onto her as she is trapped against the window frame.
|Picture by Ruth aka Kattaddorra|
If you click on the link at the top of the page you go to another page on the same subject written by Ruth who was the person who created the image on this page and who has experienced at first hand the tragedy of a cat being trapped in the tooting window. The window was not hers. The accident happened at a neighbour's home.
Cats can also be trapped in doors that are slammed shut. A cat runs through a door and at the same time the owner slams the door shut accidentally trapping her cat.