In which type of airspace is basic VFR flight not permitted during night hours without specific authorization?

Basic VFR (Visual Flight Rules) flight is not permitted in Class A airspace during night hours without specific authorization because Class A airspace is defined as being from 18,000 feet mean sea level (MSL) up to and including flight level 600, where all operations must be conducted under instrument flight rules (IFR). Pilots must have an IFR flight plan and the appropriate instrument ratings to operate in this airspace.

Class A airspace is structured to ensure safe and efficient traffic management at high altitudes, where weather conditions can be significantly different from those experienced at lower altitudes. Visibility and cloud clearance criteria needed for basic VFR operations are typically insufficient at these altitudes as flight typically occurs above the clouds and in conditions that require instrument navigation.

In contrast, Class B, Class C, and Class D airspaces allow for basic VFR flight, subject to certain conditions and communications with air traffic control, even at night, although they have their own restrictions and requirements.