Operational Navigation Chart
The Operational Navigation Charts ( ONCs ; German Operative Navigation Maps ) are a series of over 200 small-scale aeronautical charts 1: 1,000,000. The maps cover the whole world. However, individual sheets of North America, Europe, Asia and Oceania are not open to the public for military reasons.
The ONCs are mainly used in aviation and other navigation applications. The map series developed under the leadership of the USA is the successor to the never-ending project of the International World Map (IWK).
The basis is topographic information, similar to the official topographic maps of Germany and other countries. Cities, main road networks, important landscape features, railway lines, forest areas and bodies of water are shown on the map sheets. The elevation relief is represented by elevation points, contour lines (distances in feet ) and hillshading .
The maps also contain information on flight safety, such as airfields, air routes, flight restrictions and no-fly areas, as well as airspace obstacles, radio navigation systems, FIR borders and others. The maps are printed in multiple colors, the air traffic control imprint is in blue or purple.
The ONCs are designed for quick visual application and radar navigation. The cards are mainly used worldwide in aviation. The Tactical Pilotage Charts (TPC) 1: 500,000 from the ONCs are used for a closer orientation . For this purpose, an ONC sheet is divided clockwise from top left to bottom left into card sheets A to D. In 1992 the vector-based Digital Chart of the World was developed on this basis . This is a world map created by the US Defense Mapping Agency (now the National Geospatial Intelligence Agency ).
ONCs are used today by UNESCO for mapping vegetation and by the UN Food and Agriculture Organization (FAO) for high-resolution cultivation maps.
The scale of the maps is 1: 1,000,000 equals 1 cm on the map equals 10 km in the area. Geographical heights are given in feet , as is customary in aviation . The ONC use an angular cone projection according to Lambert and in the high polar regions (80 ° –90 °) a stereographic projection . A map sheet covers an area of 12 ° longitude and 8 ° latitude. The coordinate system used is the geographical system (longitudes and latitudes), the World Geographical Reference System ( Georef ) and the Australian Map Grid (a UTM network ). Both the Australian Geodetic Datum (AGD) and the World Geodetic System 1984 (WGS84) are used as geodetic datum . The sheet size for the paper maps was 146 cm × 107 cm, which is 1460 km × 1070 km. The production of paper cards by American authorities has meanwhile been discontinued.
Since the ONC was created in a military environment, little is known for certain about the origin of the underlying geodata. What is certain, however, is that a number of orthophotos were used for the maps.
- Perry-Castañeda Library Map Collection Operational Navigation Chart Series - World , many map sheets online