Final answer:
Class D airspace is controlled and requires VFR flights to establish two-way radio communication with ATC before entry. It is designed to manage air traffic safely by mandating specific separation standards.
Step-by-step explanation:
Class D airspace is a controlled airspace within which both IFR (Instrument Flight Rules) and VFR (Visual Flight Rules) operations are permitted, but VFR flights must establish two-way radio communication with the appropriate ATC (Air Traffic Control) agency prior to entering the airspace. This requirement aims to ensure that all aircraft are properly coordinated within the airspace to maintain safe distances from one another, following specific separation standards set by the Federal Aviation Administration. For instance, each airplane must maintain a distance of five miles from another plane flying at the same altitude and 2000 feet above and below another aircraft (or 1000 feet if the altitude is less than 29,000 feet), similar to the way electrons have quantized positions in quantum mechanics.