Description

Navigation by radio aids includes navigation mainly by reference to indications of bearing and distance indicated on VOR, DME and ADF equipment located on the aircraft. This information is derived from ground radio beacons (VOR, DME and NDBs or broadcast stations.)

The simplest form of navigation involves flying a direct track between a succession of VOR or NDB beacons which lie on or close to the desired track (see Figure 1.) This is the form of navigation employed in conventional airways navigation. The magnetic track and distance betwen successive beacons is measured and the calculated heading is flown, with corrections to allow for the effect of wind, until the next beacon is reached. Distance (and elapsed time) to the next beacon is read from DME or calculated by dead reckoning.

When direct beacon to beacon navigation is not possible (e.g. to avoid entering controlled airspace or danger, prohibited or restricted areas), navigation is more difficult. Two alternative methods are often used:

1. The route is plotted between radio beacons, some of which may be within controlled airspace; but the aircraft turns onto a pre-calculated track from or to another beacon before the area to be avoided is reached (see Figure 2.)

2. The direct route is plotted without reference to any paricular radio beacons and fixes are calculated along the track based on position lines plotted from radio beacons (see Figure 3.)

In practice, the simplest way of using method 2 is to pre-plot position lines during pre-flight preparation and compare actual bearings or DME ranges with pre-plotted lines (see Figure 4).

Navigating by radio aids is rapidly being supplanted by GPS navigation. However, proficiency in radio navigation remains an important skill for pilots, especially in case of GPS outages.

Further Reading

EUROCONTROL Airspace Infringement Initiative

• European Action Plan for Airspace Infringement Risk Reduction;

EUROCONTROL Guidance Notes for GA pilots

• Rules for VFR flight;
• Flight preparation;
• Getting aeronautical information before flight;
• Reading and understanding NOTAMS;
• Getting meteorological information before flight;
• Reading and understanding weather reports and forecasts;
• Using meteorological information for planning;
• Visual navigation;
• VOR/DME/ADF Navigation;
• GPS Navigation;
• Getting aeronautical and meteorological information in flight;
• Entering controlled airspace;
• Getting the most out of your transponder;

UK CAA

• Airspace & Safety Initiative
• General Aviation Safety Sense Leaflets

NTSB

• Introduction of Glass Cockpit Avionics into Light Aircraft: NTSB Safety Study.