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77 build other databases. However, since the ATO is built using command/control tools, whatever database targeteers build must be interoperable with the C2 tools of record. Nonetheless, targeteers should realize that existing databases and systems often do not work properly. Having a backup system for target database management is necessary for the times when electronic systems fail. DATUM MANAGEMENT A datum is a mathematical model of the Earth used to calculate the coordinates on any map, chart, or survey system. There are many different datums that theaters can use for their geospatial intelligence needs. It is important that targeteers, especially those conducting point mensuration, understand the different datums that are used in theater. Certain aircraft utilize different datums in their on-board computers. Maps and charts use different datums as well. Point mensuration imagery may use other datums. Understanding the different datums is crucial for ensuring aircraft systems have the correct coordinates for munitions employment. The possibility of targeting errors can greatly increase when different datums are used. During Operation DENY FLIGHT, units utilized maps and charts based on the ED-50 datum, some aircraft computers used the WGS-72 datum, and the J-2 provided target coordinates based on the WGS-84 datum. A specific coordinate plotted using a WGS-84 datum can be off by hundreds of meters if plotted using another datum. Such coordinate errors can result in devastating force employment errors, often resulting in attacking people and places that were not meant for attack. Errors can also be caused by discrepancies in vertical datums. Space-based systems, such as GPS and GPS- aided weapons, and imagery source material from sensors with space-based guidance provide coordinate elevations using the WGS-84 height above ellipsoid (HAE) datum. Most airborne navigation and littoral operations depend on mean sea level (MSL) altitudes and elevations. Both can be accurate, but the problem is that several methods to convert between HAE and MSL are in use. This often leads to conversion errors, which corrupts the HAE vertical component required in PGM tasking coordinates. In Afghanistan, garbled conversions caused problems for B-52s using joint direct attack munitions (JDAM) to attack cave entrances on vertical mountainsides. Steps have been taken to prevent datum errors from happening. Chairman of the Joint Chiefs of Staff Instruction (CJCSI) 3900.01B has been drafted to clarify guidance on using both horizontal and vertical datums and standard coordinate and height formats for most operations. The NGA produces all new maps with the WGS-84 datum and in joint operations users must now reference horizontal and vertical coordinates to this datum. GPS also broadcasts its coordinates in this same datum. However, some possibility for error still exists. NGA reproduces certain older maps that use a WGS-72 datum. Also, if one is forced to use local maps, different countries use different datums. Most of the time, utilizing datum conversion software can minimize the possibility for error. In any case, targeteers should understand the different datums used in their theater prior to hostilities so measures can be taken to ensure accurate coordinates are provided to warfighters.