The category "<flight_id-not_creatable-pl>" can be expressed as follows:

<flight_id-not_creatable-pl>

<flight_noun-pl> of <digit-pl> <specific_aircraft_type-pl>

<flight_noun-pl> of <specific_aircraft_type-pl>

<flight_type-not_creatable-pl>

<ordinal-pl> <flight_type-pl>