Chapter 4

Operating Context: Natural Phenomena

Among natural phenomena, the weather on SEA presents obvious problems for a non-pressurized altitude-limited aircraft such as the EC-47. The TEWS attributed to weather, either the loss of some time in the operating areas, or the loss of the mission entirely in 532 sorties out of a total of 11,632 flown during FY 1968. Thunderstorms, as well as terrain, and the coastline of Vietnam (through shoreline effect), interfere with effectiveness of ARDF equipment. Weather also affects the Doppler navigational system, because the B-3 driftmeter, by which it is normally reset, requires clear visiblity.

The time of day has its effect on the Doppler system as well, because the B-3 driftmeter also requires daylight. The TEWS are using other devices at night (and in weather) for resetting the Doppler. The RBS Skyspot radar device is used to obtain fixes. Also, on occassion, ceilometer lights at certain Special Forces camps are used at night to set the Doppler through the B-3 driftmeter. Wiring deficiencies in the aircraft have delayed a full test of the LORAN C for navigation and for setting the Doppler. As of this writing, a modification to correct these deficiencies is in progress.

Operating Context: Man-made Limitations

The beddown problems affecting 7AF activities in general have had their impact on the TEWS. Ideally, the squadrons at Pleiku and Nha Trang would be bases further north in RVN, so as to be closer to their operating Areas. The 361st TEWS at Nha Trang, for example, must fly as much as 1:50 to reach its farthest operating area near Hue, in the northern portion of RVN. This handicap is diminished somewhat by coducting the search for enemy transmitters, while proceeding to and from operating areas.

Other man-made phenomena, are the artillery fire and ARC LIGHT areas which dot RVN. They add a limitation to free operations by EC-47 (and other) aircraft. To keep this problem at a minimum, the EC-47 navigator closely coordinates his aircraft position with the artillery fire directors and, in the case of ARC LIGHT, with ground monitors.