This was the chain proposed for the helicopter services of New York Airways Inc. The baselines are 60 miles long. Locations are approximate. (Map courtesy Mapquest.com)

Decca coverage would be available to the three major airports in the NYC area:

a) Idlewild Airport (now called John F Kennedy International)
b) LaGuardia Airport
c) Newark Airport

CALIFORNIA

The evaluation of the Decca Navigator System by the State of California commenced on Wednesday June 10, 1970. Announced by Joseph R. Crotti, State Director of Aeronautics, a ceremony was held at Van Nuys followed by a briefing of the airborne equipment at Van Nuys Airport. A separate briefing on the marine equipment was held aboard a vessel at Marina del Ray. When the announcement was published in Decca Navigator News, it was referred to the "California Chain".

Ronald Reagan, Governor of California at the time, signs the contract for the California chain in company with members of the state legislature. (From the collection of Walter Blanchard)

The evaluation considered the advantages that the Decca System could provide in California for the navigation of ships, boats, all categories of civil aircraft and the resultant benefits to the general public.

Prior to the start of the evaluation, the system was calibrated by land, sea and air surveys. The sea calibration was carried out aboard the California Department of Fish and Game vessel Albacore. Decca ranges in excess of 200 miles from land provided good position-fixing information by day and night. Among the benefits looked for by the Californian mariner were:

* The ability of small craft to return to and enter harbours with relative safety under conditions of reduced visibility.
* Accurate identification of the position of vessels in distress during search and rescue operations.
* Ability to identify specific areas off shore and to return to such area with reasonable certainty. This is in relation to fishing, underwater obstructions , sunken vessels etc.
* Avoidance of commercial shipping lanes by small craft.

The calibration vessel Albacore. (Image courtesy Decca Navigator News, August 1970)

Within the aeronautical Evaluation Plan, some of the major operational considerations were:

* Reliability of the system, covering both fixed and airborne equipment.
* The convenience of various cockpit displays.
* Pilot training requirements.
* Advantages of Decca at lower altitudes.
* Ability to deviate from and return to course for weather avoidance.
* Use as a primary aid for instrument and low visibility approaches.
* Overall effect on safety.

The system featured an airborne flight log in the form of a cockpit display. It provided the pilot with a pictorial view of his position at all times as a map on a roller moves beneath a stylus. This indicates the present position and plots a record of the track flown.  A smaller model for light aircraft uses cross-hairs focused on the map to indicate position.  These features will help open new low-altitude airspace that is now not useable under low visibility conditions. More efficient use of airspace should relieve airspace congestion.

This was one the aeronautical displays being evaluated during the California trial. (Image courtesy Decca Navigator News August, 1970)

Aircraft and systems taking part in the evaluation:

California State Aircraft ( Beech)  Mk 15
California State Aircraft (Cessna) Mk 25
Two Golden West (Otters) Mk 15
FAA (DC-3) Mk 15
Lestro Air Taxi (Cessna 310) Mk 15
County Fire Department (Ranger Helicopter) Mk 15
 

Stations of the California chain relative to each other. Red is San Clemente Island.  Does anyone know the locations of the other sites or the chain ID ? Contact: jerry.proc@sympatico.ca  (Map courtesy Decca Navigator News, August 1970)

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References and Credits:

1) Decca Navigator News August 1970.
2) Walter Blanchard <wblanch(at)ntlworld.com>

June 2/08