Which statement about TRSA is true?

The statement regarding TRSA (Terminal Radar Service Area) that is accurate is that it provides voluntary radar services to pilots. This means that pilots flying in or near a TRSA have the option to receive air traffic control services, typically involving radar monitoring and traffic advisories. Participation is not compulsory; pilots may choose whether or not to take advantage of these services based on their own preferences and operational needs.

The nature of TRSAs is to enhance safety and efficiency in busy airspace, but it is ultimately up to individual pilots to decide if they'll utilize the radar services provided. This voluntary participation aspect is fundamental to how TRSAs operate, distinguishing them from other controlled airspace structures where compliance might be mandatory.

Other statements contain inaccuracies. For instance, participation is not mandatory for all pilots, since pilots can opt-out of using the TRSA services. Additionally, TRSAs are available to both VFR and IFR flights; thus, they are not limited to just IFR operations. Lastly, there is no requirement for a specific flight plan for participation in TRSAs, as pilots can choose to enter this airspace without needing a specific ATC flight plan.