LONG RANGE AREA NAVIGATION

1
LONG RANGE AREA NAVIGATION

• LORAN-C

2
LORAN-C

• LORAN-C is a long range navigation system based
  on LF pulse transmissions.
• The ground stations consist of a chain of master
  and secondary stations which form a network.
• The receiver measures the time difference between
  signal transmission and reception to calculate
  distance.
• A signal from a master station and at least two
  secondary stations is required to calculate
  position.

3
The master station transmits a pulse signal which
triggers transmission in the secondary stations.
Two synchronized secondary stations provide
hyperbolic lines of position. The receiver
calculates time from each station to place itself
along one of these lines (LOP). The addition of
the master station signal allows the receiver to
fix its position.
4
COVERAGE

• LORAN-C coverage encompasses the US including
  Alaska, most of Mexico and the Caribbean.
• The southern areas of Canada are covered but
  signal reception is unpredictable.
• Signal reception from transmitters can range
  from 120nm to 900nm depending on conditions.

5
GLOBAL LORAN-C COVERAGE
6
ERRORS

• There are several inexpensive receivers available
  however they are subject to navigation errors.
• Receivers may lock onto sky waves or erroneous
  signals without warning causing large errors.
• Although accuracy is normally 0.25nm errors of
  8nm are common and up to 15nm have been reported.

7

• The distance from the transmitters and the
  geometry between the receiver and transmitters
  can affect accuracy.
• Terrain also affects system accuracy.
• Transmission over water is the most accurate
  while over ground transmissions are subject to
  changes in the earths conductivity.

8

• Signals are also subject to interference from
  power lines, LF transmissions, precipitation
  static.
• The failure of one transmitter can leave a large
  area without signal coverage.
• The system gives no warning to the pilot if the
  signals are giving an inaccurate position.

9
LIMITATIONS

• Due to the many possible errors inherent with the
  system it is restricted to limited IFR use.
• It may be used for en-route IFR navigation
  subject to certain limitations and conditions.
• It is functional as a VFR navigation tool.

10
FUTURE

• The advent of GNSS has all but extinguished
  LORAN-C as a viable navigation system.
• The cost of GPS receivers make them accessible to
  general aviation consumers.
• The accuracy and integrity of GNSS greatly out
  performs LORAN-C.
• The only way you will fly with LORAN-C is in an
  aircraft with a receiver installed prior to the
  emergence of GNSS.