pilotage

Pilotage is the use of fixed visual references on the ground or sea by means of sight or radar to guide oneself to a destination, sometimes with the help of a map or nautical chart. People use pilotage for activities such as guiding vessels and aircraft, hiking and Scuba diving. When visual references are not available, it is necessary to use an alternative method of navigation such as dead reckoning (typically with a compass), radio navigation, and satellite navigation (such as GPS).

Difficulties

Pilotage depends on the pilot being able to recognise the visual references in order to make use of them. The pilot must either be familiar with those visual references or be able to discover them from a map, aeronautical chart or nautical chart. Many nautical and aeronautical disasters have resulted from the pilot incorrectly identifying visual references.

Poor visibility may affect safe navigation by obscuring the natural features used by pilots in an area. In such situations, pilots use navigational aids such as radar and the GPS to determine position and monitor their passage.

Visual features

Common types of visual reference point used for pilotage:

During the day:

• Natural features: Mountains, hills, lakes, rivers and coastal features such as cliffs, rocks and beaches
• Man made nautical features: sea marks, landmarks and radio aerials
• Man made land features: Airports, cities, dams and highways

At night:

• Man made nautical features: Lighthouses, lightvessels and sea marks with lights
• Man made land features: Airports, illuminated towers and buildings

While not strictly a "visual feature," depth, measured by electronic means or manually (with a lead line), can also be an important element of pilotage.

Pilotage is frequently combined with navigation techniques such as dead reckoning. When a pilot at a known location cannot see the next visual reference on the route to a destination, he or she can use dead reckoning to get closer to the next reference point. This is the most common form of VFR navigation.

See also

• Maritime pilot
• American Practical Navigator

References

• Bowditch, Nathaniel (2002). The American Practical Navigator. Bethesda, MD: National Imagery and Mapping Agency. ISBN 0-939837-54-4. http://www.irbs.com/bowditch/. 
• Maloney, Elbert S. (December 2003). Chapman Piloting and Seamanship (64th ed.). New York, NY: Hearst Communications Inc.. ISBN [[Special:BookSources/1-58816-098-0|1-58816-098-0]].