An aircraft which is not engaged in scheduled international air services and which is making a flight to or through any designated airport of a Contracting State and is admitted temporarily free of duty shall be allowed to remain within that State without security for customs duty:

ATPL: An aircraft which is not engaged in scheduled

For a period of 12 hours.

For a period to be established by that State.

For a period of 24 hours.

For a period of 48 hours.