Formal:
* Fleet: This is the most common and widely used term, especially in aviation contexts. It refers to a group of aeroplanes belonging to a particular company or organization.
* Squadron: This is used for military groups of aeroplanes.
* Formation: This describes a group of aeroplanes flying in a specific pattern.
Informal:
* Group: This is a general term that can be used for any collection of aeroplanes.
* Assembly: This suggests a gathering of aeroplanes, perhaps for a show or event.
* Cluster: This implies a close grouping of aeroplanes.
You can also use creative or descriptive phrases to describe a collection of aeroplanes, such as:
* A sky full of wings
* A flock of silver birds
* A ballet of aeroplanes
Ultimately, the best collective noun to use will depend on the specific situation and the desired effect.