COVER TACTICS

Because the entire ARDF function depended upon enemy radio transmissions, its success was heavily dependent upon the enemy's not knowing the aircraft's mission. Compromise would simply result in enemy shutdown of transmission, changes of frequency, or decoy transmissions from a tactically useless site. To counter this, the 460th Tactical Electronics Warfare Wing used several tactics for cover purposes: leaflet drops were made so simulate psyops aircraft, random patterns were flown - especially in absolute areas - and, until the USAF turned over its AC-47s to the VNAF, EC-47s were at altitude, indistinguishable from them. The fact that the ALR equipment and the "Y" and "Z" consoles were passive, as well as the ability of the aircraft to work on targets from standoff distances of five to seven or eight miles, aided in the deception.

The KY-8 air-to-ground transmissions, while enciphered, were nonetheless "radio transmissions" and as such could be monitored for fixing - if not for content - by the enemy's own DF capabilities, and it was known that he had them. The possible effect of this potential enemy intercept upon the enemy's tactics was not known, but there were some indications that he was aware of a possible Airborne Radio Direction Finding, or Intelligence gathering function, since on may occassions he shut down transmission when an aircraft headed toward his position. This reaction occured most often when Army aircraft, using aural null techniques, were forced to turn directly toward the enemy transmitter in order to obtain an LOP. The flight pattern of an aircraft using an aural null technique was easily recognizable to a trained observer. Having solved the problem of ambiguity, the aircraft would point toware the transmitter to obtain a "null" and an LOP. Next, the pilot would make an approximate 90 degree turn, fly what he considered to be about ten degrees of the radius of the emitted signal, perpendicular to the signal source. Following this he would turn back toward the station for another null, etc., until his LOPS converged for a usable fix. The distinctive "zig-zag" pattern of the flight would be easily identified for what it was, and it was this vulnerability which helped prompt the development of the phase-oriented system used by the ALR series, greately reducing the possibility of mission compromise.