To be able to fly from point A to point B it is important for the flight crew to know where they are and where they’re headed.
Before radar, air traffic control was dependent on pilot position reports via radio. Today, most of the time, we have radar, which makes it possible to closely track the position of aircraft.
Good knowledge about navigation and navigation aids is important for air traffic controllers and therefore we will start with a basic review of this area.
2.2 Position Reference System [C]
Positions on the earth are often given as coordinates in a coordinate system consisting of two parts, latitude and longitude.
Latitude is the coordinate giving the position in north-south direction and longitude is the coordinate giving the position in west-east direction. The earth is divided into 360 parallels of longitude or meridians. The reference or zero-meridian is located at a longitude equal to the position of Greenwich in the UK.
The longitude is expressed as the number of longitudinal degrees east (E) or west (W) of the reference meridian. In north-south direction the earth is divided into 180 parallels of latitude. The reference parallel of latitude is the equator. The latitude is expressed as the number of latitudinal degrees north (N) or south (S) of the equator.
To be able to define positions more accurately the smaller units minutes and seconds have been introduced. These units are based on the 1/60-system, which means one degree of latitude or longitude is equal to 60 minutes and one minute is equal to 60 seconds.
N590212 is the latitude and means that the position is 59 degrees, 2 minutes and 12 seconds north of the equator. W0323955 is the longitude and means that the position is 32 degrees, 39 minutes and 55 seconds west of the zero meridian.
One minute of latitude is equal to the distance of one nautical mile (nm), which is equal to 1852 meters.
One minute of longitude is not equal to the same distance everywhere on earth because the circumference of the earth is varying with latitude.
A Great circle is a circle on the surface of a sphere that has the same circumference as the sphere, and devides the sphere into two equal hemispheres. It is the largest circle that can be drawn on a given sphere.
All directions will be given relative to the North Pole. The magnetic North Pole is not located on the same position as the true North Pole and this results in two possible references of directions. If the direction is given with reference to magnetic north it is expressed in degrees magnetic, and if the direction is given with reference to true north it is expressed in degrees true.
The heading indicator in the aircraft will show the direction relative to magnetic north and consequently all headings assigned to aircraft should be in degrees magnetic.
In aviation speed is normally measured in knots, which are defined as nm/hour. 100 knots equals 185 km/h.There are different ways to measure speed.
2.6.5 Mach (M) [S]
In the upper airspace Mach is normally used to express speeds.Mach is a quotient of the local speed of sound and Mach 1.0 is equal to the speed of sound.
When giving time in aviation, it is important to define what time you refer to since an aircraft often flies trough many time zones. Hence time is always given in UTC (Universal Time Co-ordinated) in aviation.
The big difference between UTC and other time format is that UTC doesn’t change with DST (Daylight Saving Time or summertime). Adding the letter ”Z”, which is pronounced ”Zulu”, marks times given in UTC.
Dates can also be added in the format 211020Z, which means time 10:20 UTC on the 21:st.
Navigation aids are used by flight crew to navigate between different positions on the earth and may consist of transmitters on the ground, receivers in aircraft and most recently also satellites.
126.96.36.199 More on NDB [C+]
The NDB operates between 200 and 1750 kHz, but in Europe most frequencies are between 255 and 455.
188.8.131.52 More on VOR [C+]
VHF Omni-directional Range (VOR) operates between 108 and 117.950 MHz.
2.9.3 Distance Measuring Equipment – DME [S+]
Distance Measuring Equipment (DME) operates between 962 and 1213 MHz.
GPS is operating in 1,900 NM orbits, each satellite continuously transmits signals on 1227.6 and 1575.42 MHz.
2.9.6 Inerital Navigation System (INS) [C+]
For routes not forming part of the basic ATS route network
Navigational aids can be classified as almost anything, visual or otherwise, as long as it provides an aircraft with positional data.
|T||12,000 and below||25|
|H||14,500 – 17,999||100|
|H||18,000 – FL450||130|
LF/MF Radio Beacon (NDB)
|H||50 – 1,999||50|
|HH||2,000 or more||75|
If you with to learn more on the topics covered above we list a number of external links which we believe could be of interest to members in generalTime and date: