Flying cross-country when using only a chart and flying from one visible landmark to another is known as "pilotage." This method requires that the flight be conducted at comparatively low altitudes so that landmarks ahead may be seen easily. Therefore, it cannot be used effectively in areas which lack prominent landmarks, or under conditions of low visibility. Among the advantages of pilotage are the facts that it is comparatively easy to perform, and it does not require special equipment. The chief disadvantage is that a direct course is usually impractical because it is often necessary to follow a zigzag route to prominent geographical landmarks, often resulting in a longer flight.
Inasmuch as magnetic compasses are installed in all airplanes, pilotage is not the more commonly used method for a long cross-country flight. However, pilotage alone may be used on any course which affords plenty of prominent landmarks. It is accomplished by selecting two landmarks on the desired course, and then steering the airplane so that the two objects are kept aligned over the nose. Before the first of the two landmarks is reached, another more distant object should be selected and a second course steered. For the use of landmarks the pilot should take advantage of roads, railroads, and streams, but should beware of those that may vanish in mountains or dense foliage.
There is no set rule for selecting landmarks. Each locality has its own peculiarities. Consequently, a particular type of landmark may be more distinctive in one section of the country than it is in another. The general rule to follow is never to place complete reliance in any single landmark, but to use a combination of at least two or more, if practicable. One cannot depend upon only a silver water tank to identify a particular town, as every adjacent town may also have one. For identification, the pilot should check the time of passing the town against the estimated time of arrival, the number and direction of railroad lines into and out of the town, the adjacent road patterns, any nearby rivers, and the overall layout of ground references. It is well to remember that charts are not infallible. Manmade landmarks are continually being constructed throughout the country, and may not yet appear on the chart being used.
The inexperienced pilot should be impressed with the importance of becoming oriented with the surrounding area, and should be warned against spending too much time trying to find some specific landmark to the exclusion of noting the overall pattern of the area. The general pattern of roads, railroads, mountains, and other large features, give to each locality a certain distinctiveness of its own that constantly should be borne in mind. If this is done, it will be comparatively simple to single out specific landmarks from time to time to obtain accurate checkpoints.
Intersecting lines, such as railways, highways, or rivers which meet near the destination, make excellent reference brackets or boundaries to prevent the pilot from unintentionally passing to one side of the destination. In this regard, to help locate the desired airport, one need only ensure that the airplane does not cross a certain railway, highway, or river that forms the bracket.
When leaving a large city, it is usually poor practice to immediately follow a railroad or highway. It is better to fly a steady course for a few minutes after leaving the airport and not attempt to locate the desired railroad or highway until well clear of the maze of lines on the ground that generally surround a large metropolitan area.
To place dependence upon other than major roads is, in general, poor practice unless nothing better is available. Aeronautical charts do not profess to show all roads, as that would increase the clutter on the charts and require constant revisions. It will be found that some roads shown on the charts may be neither accurate, complete, nor up to date. However, the charts do attempt to give the pilot the general road pattern for the vicinity; but it should be remembered that new highways and roads are being constructed continually.
Roads shown on the charts are primarily those which are conspicuous when viewed from the air. It will be noted that surrounding terrain and other factors sometimes have a camouflage effect; the charts take this into consideration and may omit sections of the road which do not serve as good landmarks. In areas where there are few roads, a crossroad properly identified along with other landmarks in the vicinity usually will lead to a fair sized town.
Rivers usually are excellent landmarks. The curves of a winding river offer many good position references, or fixes. However, it must be remembered that rivers also have their peculiarities. In flat, woody country, rivers are sometimes confusing and hard to trace. The water is sometimes hard to detect through dense foliage unless the sunlight is reflected just right or unless it is directly below. Some rivers have so many tributaries that it is very difficult to trace the main stream. When a river is in flood stage, its appearance and surrounding area may be so changed that it will be unsafe to depend upon it as a visual checkpoint or reference line.
In the southwestern areas, the chances are that a large river shown on the chart will turn out to be nothing more than a dry arroyo during most of the year. Only by careful examination of the topography of the surrounding country is the pilot able to find adequate traces of it.
Except where there are a great many of them in the area, lakes generally offer excellent references or fixes. As with rivers, lakes also may dry up completely and disappear during certain seasons of the year. There are, also, many small artificial lakes not marked on the chart, that show up well when the sunlight reflects from them. In connection with artificial lakes created as the result of hydroelectric projects, it is well to remember these too are rapidly being developed, and they may not yet appear on the latest chart.
On the sectional charts, lakes are very often shown much larger than they really are, in order to give the general contour. Sometimes what appears to be a small lake on a chart may be just a little farm pond, or it may have dried up entirely.