From Longman Dictionary of Contemporary Englishflight of fancy/imagination/fantasyflight of fancy/imagination/fantasythoughts, ideas etc that are full of imagination but that are not practical or sensible → flight
Examples from the Corpus
flight of fancy/imagination/fantasy• This is not a flight of fancy.• Many are flights of imagination and, because of the very nature of the area, subjective.• In their more extravagant flights of fancy the choice thus offered to the voter is extended to cover specific heads of policy.• Part of the achievement of the visionary comes from inspiration that arises from considering the highest flights of imagination.• Other routines are pure flights of fancy, all the more extraordinary for the very ordinary setting.• The legend - the romantic flight of fancy was over.• There are some strange flights of fancy and there are also some extremely down to earth not to say earthy observations.• A small, balding academic sort not given to flights of fancy, Kolodney wasted no words as he made his announcement. 