The Minimum Sector Altitude (MSA) is the lowest altitude which may be used which will provide a minimum clearance of 300 m (1 000 ft) above all objects located in the area contained within a sector of a circle of 46 km (25 NM) radius centred on a radio aid to navigation. (ICAO PANS-OPS/I - definitions)
Minimum sector altitudes or terminal arrival altitudes are established for each aerodrome and provide at least 300m (1 000 ft) obstacle clearance within 46 km (25 NM) of the navigation aid, initial approach fix, or intermediate fix associated with the approach procedure for that aerodrome. (ICAO PANS-OPS/1 - Section 5, Chapter 2, §2.3)
Note. Sometimes the acronym MSA is also used to represent minimum safe altitude, which has a different meaning from minimum sector altitude, so care should always be taken to establish which term the abbreviation MSA is referring to in any particular circumstance.
Cold Temperature Correction Tool - This electronic tool (Excel Workbook) provided in conjunction with the Guidelines for Cold Temperature Corrections by ATS is intended to assist airspace designers and ATS authorities, in general, to assess how temperature correction can be most effectively accommodated in the airspace design, to identify which temperature ranges would provide the most efficient utilization of a given volume of airspace. The tool provides three spreadsheets where the user may calculate the value of the correction required for a given set of parameters, the possibility to calculate the effect of the cold temperature on the minimum vectoring altitude and the possibility to assess a the correction for temperature banding.