Final answer:
IFR aeroplanes typically do not need ATC clearance in uncontrolled airspace, but pilots should file a flight plan and follow regulations for safety.
Step-by-step explanation:
In uncontrolled airspace, IFR (Instrument Flight Rules) aeroplanes generally do not require ATC clearance for flight. The reason being, in uncontrolled airspace, the level of air traffic services available is less comprehensive than in controlled airspace, and pilots are primarily responsible for their own navigation and safety. However, pilots operating under IFR are encouraged to file a flight plan for safety and search and rescue purposes, and they must still comply with applicable regulations concerning aircraft operation and navigation.