What does INA § 252(a) permit regarding alien crewmen?

The provision under INA § 252(a) specifically allows for the conditional issuance of landing permits to alien crewmen, enabling them to land temporarily for specific purposes while ensuring compliance with immigration regulations. This means that crewmen can be permitted entry under certain conditions, which may include restrictions on their stay or activities while in the United States. The purpose of this conditional permit is to facilitate the operational needs of vessels while maintaining oversight to prevent potential immigration violations.

The other options, while related to immigration processes, do not accurately reflect the intent or content of INA § 252(a). Revocation of landing permits and mandatory detention upon arrival pertain to different aspects of immigration enforcement and do not align with the conditional nature of the permitting process for crewmen. Inspection of admissibility is a broader term that governs the entry procedures for all non-citizens and does not specifically address the context of crewmen or the conditional issuance of permits.