Final answer:
VFR aircraft must receive ATC clearance to enter Class B, C, D, and Class E (beginning at 10,000 feet MSL) airspaces, as well as in a Terminal Radar Service Area, to ensure safety and prevent airspace conflicts.
Step-by-step explanation:
VFR (Visual Flight Rules) aircraft must obtain clearance from ATC (Air Traffic Control) to enter Class B, Class C, and Class D airspace as well as Class A airspace, although VFR flights are typically not permitted in Class A.
Additionally, they must communicate with ATC when entering the Class E airspace starting at 10,000 feet MSL up to 60,000 feet MSL and at any altitude when flying within the confines of a Terminal Radar Service Area (TRSA). It is essential that these clearances are obtained to avoid conflicts and ensure the safe navigation of the skies, very much like the regulated paths of commercial airliners which maintain set distances from each other for safety.