Chapter 3

AN/ALR-34 ARDF: An electronic Airborne Radio Direction Finding unit (known as the "X" console) employes a "phase measurement" technique to determine the relative bearing of a signal to the EC-47 aircraft (i.e. the angle formed by the direction of the radio signal and the aircraft heading). The AN/ALR-34 establishes the direction of the enemy signal, as a result of computing through a complex process, the time of arrival of the target signal at the three antennas on the aircraft wins and nose.

A target-acquisition position (the "Y" console): Permits its operators, as the title implies, to search various frequencies for an enemy signal.

KY-8 radio: Permits secure communications between the "back end" crew and ground contacts (located near "Y" console in Fig. 4).

Seventeen of the forty-seven EC-47 aircraft assigned to the TEWS have additional special equipment. Twelve aircraft have two additional search/acquisition "Z" positions, and five other aircraft have two additional acquisition and jamming "Q" positions. (Fig. 5)

The navigator uses several distinctive items of equipment:

Bendix Doppler Computer CPA-24 (AN/APN-179): Enables him to fix his aircraft's position within a tolerance of 0.6 percent of the distance traveled and 1-7 percent of cross track distance. At 120 knots, this means that the maximum allowable error is 1.8 nautical miles per hour. To insure the accuracy of the computer, the navigator must check the position shown by the Doppler against a known position at frequent intervals. With this technique, he can predict the accumulation of error and also establish a proportionate part of measured error. His main resource for checking the Doppler is the relatively old-fashioned B-3 driftmeter, through which he can direct the EC-47 of a know position.

C-12 Compass System: One of the most advanced compass systems available, which gives an instant readout of aircraft heading within a tenth of a degree. It is accurate within 0.25 degrees root-mean-square (RMS) at mid-latitudes and 500 knots a far greater speed that the EC-47 can attain.)

The pilots have one non-standard piece of equipment, a Bendix Weather Radar, AN/APS-113, mounted on their instrument panels.