to perform the reconnaissance. Failure to accurately level the instrument could cause a greater error,
especially in an elevated or depressed observation.
2-46. Other Control Methods. Reconnaissance for other control methods
will vary according
physical characteristics and limitations of the equipment or system used. No matter what system or
equipment is used, the proposed station must be accessible and able to be included in the local survey
control scheme. Stations occupied by PADS must not exceed the maximum distance and time from the
2-47. Reconnaissance Party Composition. The
number according to the method of survey, the type of terrain, the available transportation, the extent of
the survey, and the density of control required. The chief of the reconnaissance party is normally the
section leader. The reconnaissance party usually consists of two to five personnel. At a minimum, the
party will include the survey party chief and the section leader. It is also helpful to include personnel for
instrument operations. The most qualified unit members should be assigned to the reconnaissance party.
A properly designed reconnaissance will result in a survey project that is accurate, complete, and
expeditious. The reconnaissance party should be thoroughly briefed on the project instructions and the
specifications of the survey mission. Reconnaissance is accomplished in three phases--office
reconnaissance, field reconnaissance, and reporting.
a. The office reconnaissance phase, which includes the gathering of existing data and a study of
applicable maps, should be completed before the start of the field reconnaissance phase. The first step is
to gather all existing data on the area to be surveyed. Depending on the area, there may be a number of
sources that maintain some type of reliable survey data. The existing data will usually consist of trig
lists, station-description cards, and aerial photographs or maps. Trig lists come in many forms,
depending upon the publishing agency. A trig list may be compiled on a DA Form 1959, horizontal-
control data booklets from the National Geodetic Survey (NGS) office, or a computer printout of
coordinates. All trig lists (officially classified or not) must be safeguarded. Once secured, this
information should be maintained as a database for that area since it may be necessary to conduct
additional surveys in the same or an adjacent area. Sources of information for reliable data include the
following units or agencies:
Local Army units (such as map depots, FA target-acquisition units, SICs, and survey units).
The NGS and the United States Geological Survey (USGS).
United States Army Corps of Engineers (USACE) district offices.
The Department of the Interior (DOI), Bureau of Land Management.
State and local government civil-engineering or survey offices.