Sunday, 22 January 2012

Omega Navigation System

The Antipodean Mariner was riding through Gippsland this weekend and passed the defunct Omega navigation station still towering over the Victorian rural landscape. Omega was a Cold War inspired long range navigation system which expanded the principles of Decca and Loran. It used synchronised, ultra-low frequency radio to create a globally intersecting grid of Lines of Position (LOP's) which could penetrate underwater. US nuclear submarines streamed an antenna and could refix their inertial navigation systems without surfacing and potentially revealing their position to an orbiting satellite.

Omega tower at Woodside, Victoria: photo credit Far_Tracer

New Zealand was the preferred site to give the best global LOP intersection, but Kiwi's were staunchly against nuclear proliferation and scuttled the station in Aotearoa.

Merchant ships were permitted to use Omega, but the system was only marginally better than a sunsight, with an accuracy of about four miles. Corrections had to be applied to compensate for the height of the ionosphere for the time of day, signal strength was patchy in the Southern Hemisphere and the LOP's distorted close (200 Nm) to any of the seven base stations. Later Omega receivers integrated the LOP's and corrections to give latitude and longitude.

Omega hardware at Port Albert Maritime Museum

Omega begat the Transit satellite navigation, which in turn begat GPS which is on your smart phone. The Omega navigation system was turned off in 1997, technically redundant after 26 years in operation. In Victoria, the Port Albert Maritime Museum inherited the hardware and have an audio-visual display of the system's operation.

The Antiodean Mariner


  1. Omega DI NOT beget Transit. They are totally different systems, and Transit predates Omega. The difference is that Transit was intermittent and had very poor water penetration ability. A sub would need to put up an antenna to get a fix as a satellite went over, but the VLF Omega signals could penetrate some distance into sea water and be picked up on a long trailing antenna.

  2. Fair comment - I didn't mean to infer that Transit was an evolution of Omega, but that it followed in terms of commercialisation. I used both and with the 'loss' of the planned Omega station in New Zealand due to political headwinds, the triangulation provided by the Gippsland antenna compromised. AM