Loran-C Grid Calibration Requirements for Aircraft Non-Precision Approach.
Abstract
The Federal Aviation Administration (FAA) Technical Center has conducted tests to measure spatial warpage and temporal instability in the Loran-C hyperbolic navigation grid. Airborne Loran-C calibration requirements identified from the test data are discussed in this report. The test results have been obtained in support of the Federal Radionavigation Plan decision process. Test emphasis is placed on non-precision approach, the flight phase for which FAA Advisory Circular AC-90-45A accuracy requirements are most stringent. Spatial warpage is assessed using Time Difference (TD) data collected at approximately 25 sites within 20 km of each of five airports. It is found that the Loran-C TD bias is the dominant warpage component and that the bias must be calibrated to meet AC-90-45A requirements for certain airports and station triads. An alternative but less accurate method than bias calibration makes use of propagation models based on mixed land/sea signal paths. Temporal instability is assessed using TD data collected over two-to-three week periods at each airport and over an entire year at a fixed-site monitor at London, KY. It is concluded that short-term instability is negligible, but seasonal instability is potentially a problem for certain regions and triads.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 17, 1982
- Accession Number
- ADA121191
Entities
People
- Leon M. Depalma
- Paul M. Creamer
Organizations
- TASC, Inc