A. IV Corps Tactical Zone

1. The IV Corps Tactical Zone, which the 175th Aviation Company (AML) shared with the 114th Aviation Company (AML), the 121st Aviation Company (AML), and the 336th Aviation Company (the latter two being located at Soc Trang), covered nearly all the Mekong Delta south and west of Saigon.  This area encompassed the major food producing region of South Vietnam and was considered the critical area wherein the struggle for freedom would be decided.  The three major ARVN units under IV Corps were the 7th, 9th and 21st Infantry Divisions.  In addition to the regular military units innumerable political sub-divisions, each requiring aviation support, existed.

B. Weather and Terrain

1. The weather and terrain conditions encountered in the Delta were akin to nothing the personnel of the 175th Aviation Company  (AML) had heretofore encountered.  During the dry season, from November to May, the skies were generally clear.  Prevailing winds were generally from the east and seldom exceeded 30 knots and dust was a primary hazard in the conduct of operational missions.

2. During the rainy season, from June to November, heavy rain showers and thunderstorms occurred almost daily.  Early morning overcast conditions were experienced frequently and the prevailing winds were from the southwest.  The temperature range was from 80 - 95 F and the humidity remained high throughout the year.  These conditions caused density altitudes to remain around 2000 feet and significantly affected the operational limitations of the UH-1B and UH-1D helicopters.

3. The terrain in the Delta was characterized by a flat, poorly drained surface, crisscrossed by an intricate network of canals and streams, with an average elevation of approximately five (5) feet.  During the rainy season the Delta was subjected to widespread flooding with up to 70 per cent of the terrain covered by one to three feet of water.  Mangrove swamps predominate in the coastal fringe area which surrounds the Delta on two sides.  The inland terrain is covered mainly with rice paddies lined with earthen dikes and levies.  Except for the trees which boarder the canals and waterways, and low lying marsh grass and weeds, there is little concealment.  Isolated jungle growth in uncultivated areas is found in several provinces and most of the populated areas are linear in pattern and situated close to bordering roads, rivers and canals.

Map of Vinh Long Area
Map of Mekong Delta

(NOTE:  These are very large files, expect a two minute download time.)