The Loran-C Secondary Phase Corrections or Additional Secondary Factors (ASF) contained in this table will, when applied algebraically to the receiver time-difference (TD) readings, increase the accuracy of the lines of position (LOP).

To find a correction, in microseconds, the table is entered directly to the nearest five minutes of arc with a dead-reckoning (DR) position or the latitude and longitude of an uncorrected Loran-C fix.

List of LORAN-C Transmitting Facilities

The basic concepts of the Loran-C Radionavigation System, and the derivation of the Secondary Phase Correction or ASF are discussed in the Introduction.

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ALSO NOTE: The Loran-C correction tables listed below were published by the Defense Mapping Agency Hydrography and Topographic Center in 1987 and 1988. They represent the latest information available and are useful for correcting older loran readings recorded prior to and shortly after that time. However, within 10 miles of the coast, ASF corrections have changed due to coastal construction throughout the United States and the increase in the number of coastal radio transmitters. Therefore, these published corrections may not be suitable for correcting more current Loran-C readings, particularly those taken in inshore areas. More current local ASF information for selected areas may be available from the sources listed below.

• C-Charts
  P.O. Box 91655
  Mobile, Alabama 36691
  Mr. John LaPointe 1-800-452-3180
  E-mail: c-charts@worldnet.att.net
  
  
• Andren Software Company
  906 S. Ramona Avenue
  Indialantic, Florida 32903-3435
  Telephone: 321-725-4115
  
  
  These are large files, please be patient.
  
  Introduction
  
  

  Secondary Phase Corrections for 5930:
  
  

  X
  

  Y
  

  Z
  
  
  

  Secondary Phase Corrections for 7980:
  
  

  W
  

  X
  

  Y
  

  Z
  
  
  

  Secondary Phase Corrections for 8970:
  
  

  X
  

  Y
  
  
  

  Secondary Phase Corrections for 9940:
  
  

  W
  

  X
  

  Y
  
  
  

  Secondary Phase Corrections for 9960:
  
  

  W
  

  X
  

  Y
  

  Z
  
  
  

  A program which will allow conversions between LORAN and geographic positions is available.

  Download Conversion File
  
  

  For more information on LORAN and the conversion program, contact:
  
  The International Association of Lighthouse Authorities (IALA), the organization responsible for the coordination of rate assignments and chain data.