(d) Local charts of terminal areas and important traffic centers suitable for special operational purposes and special landing facilities. (e) Skeleton charts for special purposes.

DESCRIPTION

The general scope and purpose of aeronautical charts shall be as follows:

(a) The basic aeronautical chart shall comprise the sheets of the 1:1,000,000 scale charts of the world aeronautical chart index produced by the United States of America for military aviation, with such subsequent alterations as experience may require, and as may be agreed upon in the future.

(b) Air navigation charts for use in long flights shall be constructed on a scale not smaller than 1:5,000,000 on either Mercator or Lambert conformal conic projections.

(c) Air route charts shall comprise charts in strip or book form to a scale not smaller than 1:2,000,000 and on that scale covering in general a width of not less than 100 miles on each side of the center line of the airway, currently revised and printed to accommodate the changes in airway facilities.

(d) Local charts shall comprise large scale base charts of terminal areas of suitable size and scale to insure safety in operation and traffic control procedures under the most exacting forms of instrument approach and let-down procedures permissible in the area.

(e) Skeleton charts for special purposes may be produced from the black and drainage plates of the basic aeronautical chart scale 1:1,000,000 or other series, in such form as subsequent developments of air navigation devices may require.

SPECIFICATIONS

Aeronautical charts shall be produced in accordance with the following detailed specifications:

(a) Projection. All charts except the Mercator long range navigation series and very small scale planning charts, and except as noted below, shall be based on the Lambert conformal conic projection. The Mercator long range navigation series shall be constructed with middle latitude to the scale of 1:5,000,000.

(1) Basic charts and charts of larger scale, between 0° and 4° latitude shall be on the Mercator projection. Charts between 4° and 72° latitude shall be on the Lambert conformal conic projection, in the three bands of the international aeronautical chart series. Charts between 72° latitude and the poles shall be on the stereographic projection. The various projection bands are designed to provide practically identical scale along the parallels of junction.

(2) The distance between parallels and meridians for basic charts shall be 30 minutes of latitude, and 30 minutes of longitude to latitude 72°. Above latitude 72°, the longitude interval shall be 1°.

(3) From 0° to latitude 52°, the meridians for each full degree of longitude shall be graduated into 1' intervals.

(4) From 52° to latitude 72°, the meridians for every other degree (even numbers) shall be graduated into l' intervals; from 72° to latitude 84°, the meridians for every fourth degree (those divisible by 4) shall be graduated into l' intervals.

(5) The parallels for each full degree of latitude shall be graduated into l' intervals from 0° to latitude 72°, and 5′ intervals from 72° to latitude 84°.

(6) For charts at other scales, meridians and parallels shall be selected for graduation so as to provide a graduated network at about the same spacing on the chart.

(7) All meridians and parallels shall be numbered in the borders of the charts. In addition, each parallel shall be numbered within the body of the chart, once near the center of each fold planned for the chart (except the end folds, for which the marginal lettering will suffice).

(b) Title and Notes. Each chart shall contain the title and notes in the language of the issuing country. Additional notes and other pertinent data shall be printed on the backs of the charts. (c) Compilation, Drafting, and Reproduction

(1) Aeronautical charts are special-purpose charts, specially designed for the use of airmen. Emphasis shall be given to cultural and topographic details of aeronautical importance, even at the expense of features normally of greater importance on an ordinary topographic map.

(2) Shore line and drainage shall normally be shown in dark full-tone blue. Open-water areas and lakes shall be outlined with a solid blue line and covered by a water tint of approximately 133line screen, of % tone value.

(3) For intermittent lakes, the shore line shall be a broken blue line, and the blue screen shall be replaced by a blue cross-rule.

(4) Salt lakes, whether intermittent or perennial, shall be so labeled, parenthetically, below the names.

(5) Double-line streams shall be those for which the actual width can be shown at chart reproduction scale, without exaggeration.

(6) Intermittent double-line streams shall be shown by a fine blue stipple delimited by intermittent stream symbols.

(7) Glaciers and ice caps, regardless of size or area, shall be shown in full and denoted by dashed outline with light form lines or flow lines on the blue plate. Approximate contour lines shown in brown shall continue across the surface of the glaciers and ice caps. Spot elevations when known shall be shown on the black plate. Areas covered by the glacier symbol should not carry the land tint or gradient tint.

(8) Snow-capped peaks may be indicated as such by a descriptive note below the peak name, in type prescribed for descriptive notes.

(9) Reefs and shoals including rocky ledges, sand, gravel, stone, and all similar areas that are exposed at low tide but covered at high tide, shall be delimited by the danger curve as indicated on the Standard Style Sheet. A fine stipple may be used within the delimited area to indicate sand or gravel.

(10) The danger curve (generally the two-fathom line) shall be shown on all charts for which the information is available, when the scale of the chart is such that it can be shown without undue exaggeration.

(11) A charted isolated rock shall be shown as one symbol, located in its true position; groups of charted rocks shall be shown by a few representative rock symbols within the area.

(12) Exposed rocks may be shown the same as an island if they are large enough to be drawn to chart reproduction scale. Rocks, if considered important, shall be named on the black plate.

(13) The elevations of rocks of sufficient height to be landmarks or hazards to air navigation shall be shown if information is available. Rocks shall be printed in black.

(14) All rocks shown on the chart shall be shown with a simple cross (the symbol used for sunken rocks on nautical charts).

(15) Only areas which are regularly liable to flood are to be indicated by the note, "Area liable to flood", in type prescribed for descriptive notes.

(16) Relief shall normally be shown by contours, in brown, with the values of the various contours indicated in brown type. For the basic charts (1:1,000,000 scale) the normal contour interval shall be 1,000 feet (approximately 300 meters). In large areas of rolling country with little difference in elevation, a 500-foot interval may be used when necessary to portray the relief more clearly.

(17) For charts of other series, the contour intervals shall be as indicated on the respective series.

(18) The gradient of elevations shall be further emphasized by layer tints as specified on the accompanying symbol sheet.

(19) Land tint (light buff) shall be used on charts which have not been surveyed for contour information. Areas not having contour information but within charts that are generally covered by contour data, and on which gradient tints are to be used, shall be left white and not overprinted with land er gradient tints.

(20) When the original source material shows dashed contours or when the required contour interval must be interpolated and in some cases where spot elevations and formlines can be used to draw approximate contours, these contours shall be dashed and layer tints used.

(21) Pictorial relief such as shading or hachuring shall be used for areas where some formline information is available but not considered adequate for dashed contours and layer tints.

(22) Spot elevations in feet shall be shown at selected critical points. In each case, the elevation selected should be the highest in its vicinity, although elevations may be shown in valleys also, to show at a glance the range in elevation. The agreement to support a worldwide series of air charts on the 1:1,000,000 scale with spot heights in feet does not naturally preclude any country from producing, for her own domestic purposes, a similar edition carrying spot heights in meters. All sheets produced in the metric system should, however, be boldly marked as such.

(23) The position of each selected elevation shall be indicated by a dot, and the elevation type shall be kept in the clear. Certain spot heights will fall in areas where the elevation, and hence the depth of tinting, may obscure the numerals. In such cases the numerals denoting the highest point of any massif should be cleared of tinting. The highest point in any sheet will always be so cleared and emphasized by a black frame around the numeral. Care should be taken, however, not to delete the layer tints from the peak itself.

(24) Escarpments shall be shown by the standard symbol on the relief plate only when they are prominent landmarks or when cultural detail is very sparse and the source of information is reliable.

The sand symbol shall not cover the escarpment symbol. Areas in which the use of this feature is intended are those similar to the bounding areas of the Sahara.

(25) Cities, railroads, highways, and the like and the type pertaining thereto, shall be shown in black.

(26) Cities and towns shall be classified according to relative importance. The following points shall be considered: aeronautical or strategic importance, population, relative importance in their own geographic areas, shape (from air photographs), classification on source material.

(27) All air markings shall be shown on the chart in the color used for aeronautical information. Towns bearing such air markings shall be shown by an underline. Other air markers established as aids to navigation shall be indicated by a symbol in the form of a triangle within which shall appear the letter M.

(28) City outlines should be of built up sections and not necessarily the established city limits, and will appear on the black plate.

(29) The same line-weight shall be used for all railroads, regardless of gauge or means of power. Single-track railroads are differentiated from those of two or more tracks by the number of crossties. All railroads, except short connecting lines in congested areas, should be named where the information is available and space permits. In dense areas railroad names may be abbreviated.

(30) Tunnels shall be shown by prescribed symbol and descriptive note if necessary to accentuate this feature.

(31) Highways and roads: Important highways should carry their numbers or names in the prescribed type on the black plate.

(32) Roads reaching the city outline shall be stopped unless they are determined to be main highways which can be distinguished from the air as definite landmarks. These highways may be shown within the city limits of cities of 100,000 population or over, by lines which shall be .010 inch in width, reproduced on the solid black plate. All other roads shall be shown by half-tone, approximately 133-line screen.

(33) For congested areas, as found in parts of the United States and Europe, roads should be shown only in areas devoid of other cultural landmarks in order to prevent overcrowding the chart. In the more congested areas, only a few super-highways should be shown, and none in metropolitan areas, except in the vicinity of airports or for other special conditions where aeronautical importance is established. Highways in these areas should not be named or numbered.

(34) For charts of smaller scale than 1:1,000,000, only the outstanding highways shall be shown, and those only in areas where undue congestion will not result. For the larger scale series additional road detail should be shown. For the local charts, scale 1:250,000 and larger, all roads possible should be shown, to provide all landmark detail possible for pilots of light planes, and for use as terminal charts by pilots of faster aircraft.

(35) Landmarks such as bridges, mines, quarries, lookout towers, forts, ruins, levees, pipe lines, et cetera, shall be shown by standard symbol or descriptive note and landmark symbol when the relative aeronautical importance is definitely established. The aeronautical importance of a feature can be determined from a flight check or photography, or where these are not available, from special types of source material or reports.

(36) Landmarks such as rock, rock outcrop, light or dark areas, jungle clearings, bluffs, cliffs, and sand dunes or any other unusual features which can be delimited from source material equal to reliable reconnaissance photography, are to be shown by the prescribed symbol used to delineate such areas. Each feature shall be labeled by the prescribed type.

(37) Landmarks or hazards to air navigation shall be designated on the black plate by the standard round or square landmark symbol, whichever best indicates the proper shape, and with a descriptive label. If the object is a hazard, the elevation of its top above sea level shall be included.

(38) Boundaries: International, state and provincial boundaries shall be shown. Boundary lines along streams shall be started and extend well into the stream. They should then be dropped. Ordinarily, only international boundaries should be shown on charts of scale smaller than 1:1,000,000.

(39) Geographic names shall be shown in black. In all countries the spelling of place names and geographic features shall follow authorized customs.

(40) The full name of the most important example of each type of feature (cape, point, gulf, river, et cetera) on any chart shall be spelled out, with a parenthetical translation of the generic part of the name if necessary for clarity, in the language of the publishing country. The names of other similar features on the particular chart may be abbreviated.

(41) Punctuation: Punctuation marks are never to be used in abbreviations or to denote possessive case, within the body of a chart.

(42) Aeronautical data shall be shown in magenta, as specified and illustrated on the accompanying symbol sheet. The size of the symbols shown is as recommended for the basic charts (1:1,000,000 scale) and may be enlarged or reduced as required for charts of larger or smaller scales.

(43) Only prominent transmission lines (usually steel-tower lines) or those deemed hazardous to air navigation shall be shown. On charts of 1:1,000,000 scale or smaller, even these may be omitted in congested areas, leaving the more complete information to be represented on charts of the larger scale series.

(44) Overlaps of about 15 minutes will be provided by extending all information and detail, except and and water tints, from the limiting parallels and meridians of each chart at least on the north and east sides to the neat line.

(45) Scale shall be shown fractionally in the margin and graphically along all four borders in accordance with the appropriate style sheets. The graphic scales for each chart shall be based upon the scale at the middle latitude of that chart. Linear scales may be added in the margins in such units of length as commend themselves to the user nations.

(46) Countries which may desire to show on the aeronautical charts which they publish particularly interesting details, for which no international symbol has been provided or in cases where use of the international symbol would be likely to cause confusion, shall be free to choose for this purpose any appropriate conventional symbol; but they must explain it in the margin of the map in a small table of additional symbols.