Crowded skies make the controller＇s work more arduous. The UK National Air Traffic Services (NATS) has come up with a solution to lighten the load and handle some of the mundane tasks. Operational Trials with a new Short-term conflict Alert (STCA) system have just started at the Manchester Area Control Center and will soon start at the London Central Control Function. The new short-term conflict alert warns controllers by visual and / or audible signs that aircraft are in danger of collision. For the first time, the system has been adapted for terminal use, and can be modeled to the complex skies around an airport such as London Heathrow. A new NATS Operational Display Equipment (NODE) system is under opera tional evaluation at the Manchester Centre and planned for the London Area Central Control Function, New En-Route Centre, and Scottish Centre. It can define regions of airspace and can vary the parameters according to airspace type – en-route, TMA, advisory, ap proach, departure or stack and apply separation standards. The NODE STCA software applies three filters to multi-radar track data and Mode C al titude inputs in order to identify pairs of aircraft that are in conflict or could come into con flict within two minutes. A linear prediction filter extrapolates recent tracks forward laterally and vertically. A current proximity filter measures actual lateral and vertical separations to detect aircraft deviating suddenly from an acceptable separation. A maneuver hazard filter examines the position of all turning aircraft at similar altitudes, assuming a 3deg/sec turn rate. To minimize unnecessary alerts caused by such factors as Mode C errors or aircraft leveling off or turning away from conflicts, at least one filter must be passed at least twice to generate an alert. Unless there is an imminent danger of collision the alert is held back until the latest time that an instruction to take avoiding action could be issued and acted on. At that point the labels of conflicting aircraft on the controller’s screen start to flash bright/dim, a dotted line links the targets involved, and the label information is displayed in a con flict alert box. The system distinguishes between low-intensity and high intensity alerts—including all current proximity and maneuver hazard alerts, which are designated by an asterisk and can not be acknowledged. The NODE-M STCA algorithm has also been designed to anticipate Traffic Alert and Collision Avoidance System (TCAS) alerts in 90 percent of cases. One source of unnecessary alerts is aircraft transitioning to a cleared flight level which is one level away from another aircraft NODE STCA does not take account of controller-input cleared fight levels, since that would lead to failure to detect potential conflicts when aircraft bust their cleared level. However, intention data from aircraft flight management systems is expected to be available in the future via Mode S data link, and research by the UK Defense Research Agency (DRA) suggests this could virtually eliminate level-off alerts.4. According to the passage, might result in unnecessary alerts.