How do you evaluate the performance and reliability of VOR and DME systems?

1 What is VOR?

VOR stands for Very High Frequency Omnidirectional Range. It is a radio-based system that provides directional information to aircraft. A VOR station on the ground emits a signal that rotates 30 times per second. The signal consists of two components: a reference phase and a variable phase. The reference phase is the same for all directions, while the variable phase changes depending on the angle of the signal. By comparing the phases of the two components, an aircraft can determine its bearing from the station.

2 What is DME?

DME stands for Distance Measuring Equipment. It is another radio-based system that provides distance information to aircraft. A DME station on the ground responds to interrogations from an aircraft by sending back a reply. The aircraft measures the time delay between the interrogation and the reply, and calculates the distance from the station based on the speed of radio waves. DME stations are often co-located with VOR stations, forming a VOR/DME system that provides both directional and distance information.

3 How to use VOR and DME?

To use VOR and DME, an aircraft needs to have a VOR receiver and a DME transponder. The VOR receiver displays the bearing from the station on a gauge called a VOR indicator. The DME transponder displays the distance from the station on a digital readout. The pilot can tune the frequency of the VOR and DME stations on a radio panel, and select the desired radial or course on the VOR indicator. The radial is the angle of the signal from the station, and the course is the desired direction of flight relative to the station. By following the VOR indicator and the DME readout, the pilot can fly along a specific course and distance from the station.

4 How to evaluate VOR and DME performance?

To evaluate the performance and reliability of VOR and DME systems, there are several factors to consider. One factor is the accuracy of the systems, which depends on the quality of the signals and the calibration of the equipment. The accuracy of VOR and DME can be affected by atmospheric conditions, terrain, interference, and errors. Another factor is the availability of the systems, which depends on the coverage and serviceability of the stations. The availability of VOR and DME can be affected by maintenance, outages, and limitations. A third factor is the usability of the systems, which depends on the ease of operation and interpretation of the equipment. The usability of VOR and DME can be affected by the design, layout, and functionality of the instruments and controls.

5 How to test VOR and DME accuracy?

To test the accuracy of VOR and DME systems, there are several methods that can be used. One method is to use a ground check point, which is a location on an airport or near a VOR station that has a known bearing and distance from the station. The pilot can tune the VOR and DME frequencies, and compare the readings on the instruments with the expected values. Another method is to use an airborne check point, which is a location along a specific radial or course that has a known distance from the station. The pilot can fly over the check point, and compare the readings on the instruments with the expected values. A third method is to use a dual VOR check, which is a procedure that involves using two VOR receivers and comparing their readings. The pilot can tune one receiver to a VOR station, and another receiver to a different VOR station. The pilot can then select a radial or course on both receivers, and compare the difference between their readings. The difference should not exceed 4 degrees.