bearing

As bearing ( Low German aiming of medium latin Pagella (bar), etymological related to level ) are in the nautical and navigation referred to methods by which the angle between the direction for a gepeilten object and a reference direction is measured, on the other hand, the angle determined is itself referred to as a bearing.

For the overriding topic, see direction measurement .

If the observer determines the direction of his own movement, one speaks of the course ( English course or track ).

Reference systems for bearing

Bearing from the Rothen Tonne via the Scharhörnbake (1) to the Great Neuwerk lighthouse (4) to the entrance to the Elbe estuary around 1831. Other landmarks: Nordbake (2) and Kleiner Leuchtturm (3).

The most frequently used absolute reference system is given by the cardinal points . Measurements relative to the astronomical north direction are in nautical as pointing right referred to those to magnetic north , however, as miss-setting . In nautical and air navigation, the following types of destinations are mainly used in addition to the cardinal direction:

distinctive, stationary objects on the coast or on traffic routes ( landmarks )
natural points like stars , moon and sun , mountains, capes, islands
artificial points such as radio beacons or beacons and special navigation marks

Bearings are not only taken in shipping and aviation , but also in everyday life. In addition to the cardinal points, people like to use information such as 10 o'clock . The reference system is your own pre-alignment and the setting of the angle is done with the dial of a clock, the 12 o'clock marking points away from the viewer (the indication “10 o'clock” corresponds to 60 ° left).

Simpler and less precise types of bearing are sometimes even done unconsciously if they relate to your own pre-alignment - for example with the words to the left in front of us or to the right of you .

Optical direction finding, radio direction finding and radar direction finding

If the direction to the targeted object is determined visually , i.e. essentially by looking at it, the direction of which is determined, one speaks of optical bearing .

In radar direction finding , a radar impulse replaces the human eye, it is (in simplified terms) the direction in which a radar signal transmitted by the user is reflected is determined.

In radio navigation, on the other hand, the angle at which the radio waves emitted by a ground transmitter arrive at the measuring point is measured, the so-called radio direction finding . The radio location can be determined from two or more radio landlines determined in this way, cf. Cross bearing .

In radio navigation, in contrast to the rest of the navigation, courses are generally referred to magnetic north, as the cockpit instruments indicate magnetic courses for VOR and NDB . Therefore, magnetic bearings play a special role.

Radio direction finding
- A direction finder can be used to determine the direction from which incoming radio waves are coming.
- with ADF , (radio compass, automatic detection of ambiguity )
- with VOR
- with long-range navigation systems such as LORAN-C

This must be distinguished from satellite navigation , which also uses radio waves, but is not based on angle measurement, but on the measurement of signal transit times.

Special DF methods

Alignment

As Alignement is called the bearing along an edge of the house , building line or another line or plane.

Cross bearing

A cross bearing (Engl. Crossing bearing ) results when being targeted from one location two different objects of known location. The intersection of the two stand lines is your own location. For details see: Terrestrial navigation # Cross bearing

Sailing bearing, four-line bearing

If an object is sighted from two different locations, the distance to the sighted object can be determined from the distance between the locations and the measured angles. For details, see: Terrestrial navigation # Seaworthiness bearing

Bearing vertical angles (elevation)

In principle, you can also use a bearing to determine points of the same height - for example, by sighting the opposite mountain or mountain slope above the water level of the drinking bottle.

Thumb bearing

Using the thumb bearings , you can approximately determine angles even without technical measuring devices.

Jump of the thumb

The jump of the thumb is very similar to the sail bearing. The distance to an object of known size can be estimated by alternating bearings with the right and left eye and with the aid of the theorem of rays .

Bearing over the sun and moon

The sun and moon both have an apparent diameter of almost exactly half a degree. Since both of them “rotate around the earth” about once a day, they cover 720 times their own diameter on their way around the earth. In this way they move around their own diameter and thus half a degree in 2 minutes, a whole degree in 4 minutes, two degrees in 8 minutes, and so on. So you just have to look at the clock, wait a correspondingly long time and have an arc in the sky with the desired angle.

Bearing as an angle

True bearing

As a true bearing (engl. True bearing , TB) refers to the angle between the right-facing north and the gepeilten object. The true bearing is mainly used when working with maps that are usually correctly oriented.

Radio navigation special case

Magnetic courses are indicated in radio navigation maps, therefore magnetic bearings and courses are generally used in radio navigation.

Magnetic bearing

The magnetic bearing is the angle between magnetic north and the object being sighted. The measurement is carried out clockwise. See also: Declination (geography)

Magnetic compass bearing

As a magnetic bearing or magnetic compass bearing (engl. Magnetic bearing , MB) is the angle between magnetic compass north (engl. Magnetic north , MN) designated and the gepeilten object. The measurement is carried out clockwise. The magnetic compass bearing corresponds to the magnetic bearing plus any deflection by local magnetic fields. See also: Deviation (navigation)

Side bearing

Angle between your own vehicle direction z. B. Cross abeam and the object being sighted (e.g. "two lines astern than starboard abeam")

Radio side direction finding in aviation

With relative bearing (engl. Relative bearing , RB) is the angle between the aircraft longitudinal axis and the radio base line , d. H. of the plane - ground transmitter line , measured clockwise. Specifying the RB alone is not enough to determine where the aircraft is on the line to the ground station. This requires a further bearing.

Further use

As a bearing or direction finding is also referred to the measurement of water depths or receiving a riverbed .

Use in a figurative sense

Colloquially, the term "bearing" is also used in the sense of "orientation". As a rule, what is meant is not the spatial, but the factual orientation ability of a person, i.e. their cognitive ability and / or competence (“You don't have a bearing at all!”, “After the third explanation, he took a bearing”).

literature

Otto Lueger : bearing (lexicon entry). In: Lexicon of all technology and its auxiliary sciences. 2nd edition, Deutsche Verlagsanstalt, Stuttgart and Leipzig 1904–1920. 1920, accessed February 10, 2019 .
Otto Lueger: Peilen / Peilen (encyclopedia entry). In: Lexicon of all technology and its auxiliary sciences. 2nd edition, Deutsche Verlagsanstalt, Stuttgart and Leipzig 1904–1920. 1920, accessed February 10, 2019 .