The Physical Supervision unit performs the inspections requested by the Customs Control Centre, Customer Management and Declaration Processing units. Each day, a variety of checks are carried out, such as inspecting goods stored in warehouses, and aircraft searches, often using sniffer dogs to carry out a thorough search of airplanes, as well as inspecting selected mail packages and letters, airline plates and containers. The latest technology is used to ensure inspections proceed in the swiftest and safest way possible. Examples include the use of a variety of detection devices, such as the backscatter van, which drives around the plane and allows the analyst to evaluate real-time images, or the mobile scanning unit, which is used to scan crew baggage and other items not included in the manifest. And of course there is the fixed scanning unit, to which whole plates are taken from the plane for scanning, under the supervision of Customs officers.