5.2.2 Navigation aid
Navigation aids are points on the landscape, which are used to determine the position of the aircraft and are also used as waypoints for flight routes.
In controlled airspace (manned) aviation there are three basic types of navigation aids:
1. Non-directional
beacon (NDB): The ID for NDBs has three letters. This type of radio beacons is
mostly obsolete nowadays. They operate at low frequencies and don´t provide
inherent and precise directional information. FlightZoomer does not model NDBs.
More information can be found here:
http://en.wikipedia.org/wiki/Non-directional_beacon
2. VHF
Omnidirectional Range (VOR): The ID for VORs has three letters. VORs are still
in use in aviation today. They offer exact measurements of the radial on which
the aircraft is located. A subtype are VORDMEs which additionally offer a
distance measurement. Tuning to a single VORDME enables unambiguous
determination of the current position.
More information can be found here:
http://en.wikipedia.org/wiki/VHF_omnidirectional_range
3. Fixed geographic coordinates (GPS FIX): The ID for GPS FIXs has five letters. These are fixed positions which were defined to support airways and flight paths without the need to install ground based radio beacons. They far outnumber VORs in most airspaces. As they don’t emit any radio signals they can only be used for aircrafts which can determine their location autonomously. Due to GPS and other advanced systems this is almost always the case today.
FlightZoomer implements the VOR, VORDME and GPS FIX navigation aid types.
A navigation aid has the following properties:
|
|
Element |
Purpose |
|
1 |
ID |
The ID identifies a certain navigation aid and needs to be distinct within the whole navigation database. It consists typically of 3 to 5 uppercase letters (3 letters for VORs and VORDMEs and 5 letters for GPS FIXs). FlightZoomer does not restrict the character count so any desirable ID can be assigned to navigation aids (and thus be displayed on the Navigation Display). The ID is mandatory. |
|
2 |
LOCATION |
The location is also mandatory and defines the geographic coordinates. It consists of longitude and latitude. |
|
3 |
TYPE |
The possible types are VORDME, VOR and GPS FIX. The first would offer distance measurement and radial capturing, the second only radial capturing and the third could not be used for radio navigation but only for flightplans. However, there is currently no different behavior implemented for each of these, so each type would represent a VORDME (with the small exception, that leaving away the frequency would emulate a GPS FIX). |
|
4 |
FREQUENCY |
The frequency is used to tune to a certain navigation aid. It also needs to be distinct within the whole navigation database. The frequency property is not mandatory and can be left empty. In that case the navigation aid emulates a GPS FIX and would not be useable for radio navigation. |