Overview

Navigational aids is the way we name all those things which flight crew use in order to navigate between different points on the earth. They mainly work with transmitters on the ground, receivers on aircraft and satellite navigation equipment too.

These aids are called VORs, NDBs and intersection/FIXs. All of these are waypoints.

NDBs

Non-Directional Beacon

An NDB is a ground-based radio station which transmits non-directional radio signals. This means that they only send one signal which expands in all directions.

To determine the direction or "bearing" to an NDB from an aircraft, pilots use an ADF indicator.

NDBs generally have a range between 50-100nm, an NDBs identified by 3 letters have usually got a longer range than those identified by 2.

VORs

Very high freq. Omni-directional Radio range

A VOR is basically the same as an NDB station, BUT more precise. Why? Well, instead of transmitting only one signal which spreads out in all directions, a VOR transmits a different signal in every direction. By using navigation equipment, it is possible to fly any direction from/towards the beacon. These directions are called radials.

If you fly towards the south from a VOR, you'll be flying on the 180 radial. Now, if you're at the south of a VOR and are pointing towards the north, you'll still be on the 180 radial, but heading 360.

When flying towards a VOR, it is common to say you are on a radial inbound to it.If flying away, then you'll be on a radial outbound.

A VOR usually has a range between 100-200nm.

DME

Distance Measuring Equipment

Hmmmm... we are still thinking what may be the use of this piece of equipment.

Apart from the obvious (its use), it's also important to know that this device cannot be used to determine the position with respect to it.

Intersection/FIX

This is a type of navigation aid which is not ground-based. Instead, it is a point defined on the surface of the earth using the position-reference system (coordinates). Because of this, it cannot be used using conventional navigation instruments. In order to be able to use it, an aircraft has to be equipped with RNAV Navigation (Area Navigation) equipment.

RNAV equipment works by using different ground aids (VOR/DME) for reference, as well as GPS positions and INS/IRS data.

GPS

Global Positioning System

GPS is a satellite-based positioning system. It was developed for use on land, sea and air, and provides a highly-accurate three-dimensional position globally.

FMS

Flight Management System

FMS is the word used to describe a complex centralized system which is used for navigation. It can alsoo be referred to as multi-sensor RNAV 

It uses data from many different sensors (including, but not limited to fuel flow, atmoshperic and navigation data), to compute and calculate its accurate position. Depending on their capabilities, they are authorized for different types of use, but most of them for en-route IFR in most classes of RNAV airspace.

The FMC (Flight Management Computer) contains a database with all regional or worldwide navigation aids (FIX, VOR, NDB, etc...).

A VATSIM Europe Division service.
Content updated:  6. September 2018.