Comparison of Accuracy
| System | 95% Accuracy (Lateral / Vertical) |
Details |
|---|---|---|
| LORAN-C Specification | 460 m / 460 m | The specified absolute accuracy of the LORAN-C system. |
| Distance Measuring Equipment (DME) Specification | 185 m (Linear) | DME is a radionavigation aid that can calculate the linear distance from an aircraft to ground equipment. |
| GPS Specification | 100 m / 150 m | The specified accuracy of the GPS system with the Selective Availability (SA) option turned on. SA was employed by the U.S. Government until May 1, 2000. |
| LORAN-C Measured Repeatability | 50 m / 50 m | The U.S. Coast Guard reports "return to position" accuracies of 50 meters in time difference mode. |
| eLORAN Repeatability | Modern LORAN-C receivers, which use all the available signals simultaneously and H-field antennas. | |
| Differential GPS (DGPS) | 10 m / 10 m | This is the Differential GPS (DGPS) worst-case accuracy. According to the 2001 Federal Radionavigation Systems (FRS) report published jointly by the U.S. DOT and Department of Defense (DoD), accuracy degrades with distance from the facility; it can be < 1 m but will normally be < 10 m. |
| Wide Area Augmentation System (WAAS) Specification | 7.6 m / 7.6 m | The worst-case accuracy that the WAAS must provide to be used in precision approaches. |
| GPS Measured | 2.5 m / 4.7 m | The actual measured accuracy of the system (excluding receiver errors), with SA turned off, based on the findings of the FAA's National Satellite Test Bed, or NSTB. |
| WAAS Measured | 0.9 m / 1.3 m | The actual measured accuracy of the system (excluding receiver errors), based on the NSTB's findings. |
| Local Area Augmentation System (LAAS) Specification | The goal of the LAAS program is to provide Category IIIC ILS capability. This will allow aircraft to land with zero visibility utilizing 'autoland' systems and will indicate a very high accuracy of < 1 m. |
Read more about this topic: Wide Area Augmentation System
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