Transshipment of cargo by air requires CTM approval, escorted supervised transfer, and bond debit and re credit procedures. Transshipment of cargo by air prescribes that carriers file for transshipment with the Cargo Transfer Manifest treated as the application, obtain Proper Officer approval, and move consignments escorted by Preventive Officers under Customs supervision. Warehouses must use a double locking arrangement with keys held by the airlines/custodian and Customs. Transshipment Bonds are debited on dispatch and re credited on presentation of destination acknowledgements; marks and numbers are normally verified without physical examination except on credible intelligence.