unit or some other feature of the resource. Each vehicle working the current shift has an icon placed in the column describing the unit's current status. A log book is used to track times, event details, and other information about calls for service. In a tow truck example, the icon might be labelled with the tow car's radio identifier, "Down town 6". During a shift, the icon would be moved by the dispatcher into whatever column describes the resource's current condition. Alternatively, there could be columns for some other condition such as the names of move-up or standby points where resources are sent to backfill for busy tow cars. A major flaw of this system is that icons can easily be misplaced or fall off of the status board. Magnetic objects can damage cathode ray tube displays if they get too close to the display face or housing. Airline dispatch In airline operations in a few countries, a dispatcher shares legal responsibility for a flight's safety with its pilot, and may delay, divert or cancel a flight if there is reason to do so. This checks and balances mechanism supposedly improves the safety of the dispatch system, although most countries do not use this system and there is no noticeable detriment to flight safety. A dispatcher typically must be licensed by the aviation authority of a country. The examination for the licence requires the candidate to demonstrate knowledge in meteorology and aviation comparable to that required to obtain an Airline Transport Pilot Licence. Mobile dispatch In a mobile system, wireless technology is provided for efficient job planning, assignment and efficient job planning through the use of mobile dispatch systems sent out through a mobile network on to a mobile device such as PDA. This allows for more flexible management of the workers out in the field as a job can be dispatched to multiple users to accept or reject the job. The benefits of a mobile system as it can then be integrated back into the other software systems used by an organization such as asset management, rostering, and other financial systems. Trucking dispatch Trucking dispatchers play a major role in transportation logistics. Truck dispatchers orchestrate freight movement and equipment from one place to another while keeping close communication with truck drivers. Some dispatching companies help truck drivers to negotiate and acquire loads and handle paperwork. Dispatching trucks require a