MIL-HDBK-162A
Volume 1
15 December 1965
Section 2
DATE: 1 July 1961
ITEM NAME: GROUND POSITION INDICATOR
COGNIZANT SERVICE: USN
TYPE: AN/APA-57
FEDERAL STOCK NUMBER:
USA
USN
USAF
USMC
STATUS OR TYPE CLASSIFICATION
Mfg(s) Name or Code Number:
the relative position of the aircraft from an initial ground
FUNCTIONAL DESCRIPTION
reference. The resultant N-S and E-W coordinates are
converted into corresponding variable dc voltages which
The AN/APA-57 is airborne equipment used to
are used to stabilize the PPI presentation of radar
indicate the displacement in naut mi of the aircraft from
indicating systems, including Indicator Assembly
an initial ground position in terms of N-S and E-W
AN/APA56 or Indicator Group AN/APA-81.
coordinates. From true air speed, heading and wind,
The AN/APA-57 also supplies ground displacement
and information supplied to various units of the
equipment, the AN/APA-57 derives direct indication of
AN/APA-57: 1
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