Final answer:
Class D airspace is the correct classification for primary airports within a TRSA, offering radar vectoring, sequencing, and separation for aircraft, although TRSA is not considered formal controlled airspace like Class B, C, or D.
Step-by-step explanation:
The primary airport(s) within the TRSA (Terminal Radar Service Area) become(s) Class D airspace. When a TRSA is not operating, such as at night, the airspace reverts to Class E or Class G airspace, depending on the specific airport and how the airspace is charted. TRSA is designed to provide radar vectoring, sequencing, and separation on a full-time basis for all IFR and participating VFR aircraft. The purpose of the TRSA is to ensure that all participating aircraft operate safely in the vicinity of the primary airport by providing radar coverage sufficient for air traffic control to offer separation and sequencing, even though it is not formally considered controlled airspace in the same regulatory sense as Class B, C, or D.LearnmoreaboutTRSAAirspace.