The American Practical Navigator/Acronyms

by the United States government

GLOSSARY OF ABBREVIATIONS AND ACRONYMS

A

A	amplitude; augmentation; away (altitude intercept); Arctic/Antarctic (air mass)
a	semimajor axis
a	altitude intercept (Ho~Hc); altitude factor (change of altitude in 1 minute of time from meridian transit); assumed
ABAND	abandoned
AC	alternating current; altocumulus
ACC	Antarctic Circumpolar Current
add'l	additional
ADF	automatic direction finder
ADIZ	air defense identification zone
AEB	acquisition exclusion boundary
AERO	aeronautical
AF	audio frequency
AFC	automatic frequency control
AGC	automatic gain control
AISM	Association Internationale de Signalisation Maritime (International Association of Lighthouse Authorities)
aL	assumed latitude
Al., Alt,	alternating (light)
A.L.R.S.	Admiralty List of Radio Signals.
am	amber
AM	amplitude modulation
AM	ante meridian (before noon)
Anch	anchorage
antilog	antilogarithm
AP	assumed position
approx.	approximate, approximately
ARPA	automatic radar plotting aid
ASAM	anti-ship action message
ASF	Additional Secondary Phase Factor
AT	atomic time
AU	astronomical unit
AUSREP	Australian Ships Reporting System
al	assumed longitude

B

B	atmospheric pressure correction (altitude); bearing, bearing angle
Bdy Mon	boundary monument
BFO	beat frequency oscillator
BIH	Bureau Internationale de l’Heure
BIPM	International Bureau of Weights and Measures
bk	broken
bkw	breakwater
bl	blue
BM	bench mark
Bn	beacon
Bpgc	bearing per gyrocompass
br	breakers
Brg.	bearing (as distinguished from bearing angle).
bu	blue

C

C	Celsius (centigrade)
C	chronometer time
C	compass (direction)
C	correction
C	course
C	course angle
C	can
C	cylindrical
C	cove
CALM	catenary anchor leg mooring
CB	compass bearing
CBDR	constant bearing, decreasing range
CC	compass course
CC	chronometer correction
CCIR	International Radio Consultative Committee
CCU	Consultative Committee for Units of the International Committee of Weights and Measures (CIPM)
CCZ	Coastal Confluence Zone
cd	candela, candelas
CD	chart datum
CD-ROM	compact disk-read only memory
CG	Coast Guard
CE	chronometer error
CE	compass error
CFR	Code of Federal Regulations
cec	centicycle
cel	centilane
CEP	circular probable error
CES	coast earth station
CFR	Code of Federal Regulations
CGPM	General Conference of Weights and Measures
CH	compass heading
CIPM	International Committee of Weights and Measures
Cl	clearance
cm	centimeter(s)
CMG	course made good
Cn	course (as distinguished from course angle)
co	coral
co-	the complement of (90° minus)
COA	course of advance
COE	Committee on ECDIS (IHO)
COG	course over ground
coL	colatitude
colog	cologarithm
corr.	correction
cos	cosine
cot	cotangent
cov	coversine
CPA	closest point of approach
CPE	circular probable error
Cpgc	course per gyrocompass
cps	cycles per second
Cpsc	course per standard compass
Cp stg c	course per steering compass
CPU	central processing unit
crs	course
CRT	cathode-ray tube
csc	cosecant
cup	cupola
Cus Ho	customs house
CW	continuous wave
CZn	compass azimuth

D

D	deviation
D	dip (of horizon)
D	distance
D	destroyed
d	declination (astronomical)
d	altitude difference
d	declination change in 1 hour
dA	difference of longitude (time units)
DC	direct current
deg.	degree(s)
Dec.	declination
Dec. Inc.	declination increment
Dep.	departure
destr	destroyed
Dev.	deviation
DG	degaussing
DGPS	differential global positioning system
DHQ	mean diurnal high water inequality
Dia	diaphone
diff.	difference
Dist.	distance
D. Lat.	difference of latitude
DLo	difference of longitude (arc units)
DLQ	mean diurnal low water inequality
dm	decimeters
DMAHTC	Defense Mapping Agency Hydrographic/Topographic Center
DNC	digital navigation chart
dol	dolphin
DR	dead reckoning
DR	dead reckoning position
DRE	dead reckoning equipment
DRM	direction of relative movement
DRT	dead reckoning tracer
Ds	dip short of horizon
DSC	digital selective calling
DSD	double second difference
DSVL	doppler sonar velocity log
dur.	duration
DW	Deep Water Route
DZ	danger zone

E

E	east
e	base of Naperian logarithms
e	origin of own ship’s true vector
e	eccentricity
EBL	electronic bearing line
ECD	envelope to cycle difference
ECD	envelope to cycle discrepancy
EC	electronic chart
ECDB	electronic chart data base
ECDIS	electronic chart display and information system
ED	existence doubtful
EDD	estimated date of departure
EEZ	exclusive economic zone
EGC	enhanced group calling
EHF	extremely high frequency
E. Int.	equal interval
E. Int.	isophase
EM	electromagnetic (underwater log)
em	other ship’s true vector
ENC	electronic navigation chart
ENCDB	electronic navigation chart data base
EP	estimated position
EPIRB	Emergency Position Indicating Radiobeacon
EPROM	erasable programmable read only memory
Eq.T	equation of time
er	own ship’s true vector
ET	Ephemeris Time
ETA	estimated time of arrival
ETD	estimated time of departure
Exting	extinguished

F

F	Fahrenheit
F	fast
F	longitude factor
F	phase correction (altitude)
F	fixed (light)
f	latitude factor
f	flattening or ellipticity
F.Fl.	fixed and flashing
Fl.	flashing (light)
Fl. (2)	group flashing (light)
Fl. (2+1)	composite group flashing (light)
fm(s)	fathom(s)
FM	frequency modulation
Fog Det.	fog detector
Fog Sig.	fog signal
ft.	foot, feet
FTC	fast time constant

G

G	Greenwich
G	Greenwich meridian (upper branch)
G	grid (direction)
G	gravel
G	green
g	acceleration due to gravity
g	Greenwich meridian (lower branch)
GAT	Greenwich apparent time
GB	grid bearing
GC	grid course
GCLWD	Gulf Coast Low Water Datum
GDOP	geometric dilution of precision
GE	gyro error
GH	grid heading
GHA	Greenwich hour angle
GMDSS	Global Maritime Distress and Safety System
GMT	Greenwich mean time
Gp. Fl.	group flashing
GP	geographical position
GPS	Global Positioning System
Gr.	Greenwich
GRI	group repetition interval
GST	Greenwich sidereal time
GV	grid variation
GZn	grid azimuth

H

h	altitude (astronomical)
h	height above sea level
h	hours
ha	apparent altitude
Hc	computed altitude
Hdg.	heading
HE	heeling error
HE	height of eye
HF	high frequency
hf	height above sea level in feet
HHW	higher high water
HHWI	higher high water interval
Hk	hulk
HLW	higher low water
HLWI	higher low water interval
hm	height above sea level in meters
Ho	observed altitude
Hor	horizontal
Hor Cl	horizontal clearance
HP	horizontal parallax
Hp	precomputed altitude
Hpgc	heading per gyrocompass
Hpsc	heading per standard compass
Hp stg c	heading per steering compass
hr	rectified (apparent) altitude
hr.	hour, hrs., hours
hs	sextant altitude
HSD	high speed data
ht	tabulated altitude
HW	high water
H.W.F.&C.	high water full and change
HWI	high water interval
HWI	mean high water lunitidal interval
HWQ	tropic high water inequality
Hz	Hertz

I

I	instrument correction
i	inclination (of satellite orbit)
IALA	International Association of Lighthouse Authorities
IAU	International Astronomical Union
IC	index correction
ICW	Intracoastal Waterway
IGLD	International Great Lakes Datum
IHB	International Hydrographic Bureau
IHO	International Hydrographic Organization
IMO	International Maritime Organization
in.	inch, inches
INM	International Nautical Mile
INMARSAT	International Maritime Satellite Organization
INS	inertial navigation system
int.	interval
Int. Qk.	Interrupted quick flashing
ION	Institute of Navigation
I.Q.	interrupted quick flashing
IR	interference rejection
IRP	image-retaining panel
ISLW	Indian spring low water
ISO	International Order of Standardization
ISO	isophase (light)
ITU	International Telecommunications Union
IUGG	International Union of Geodesy and Geophysics
I.U.Q.	interrupted ultra quick flashing
I.V.Q.	interrupted very quick flashing
IWW	Intracoastal Waterway

J – K – L

J	irradiation correction (altitude)
K	Kelvin (temperature)
kHz	kilohertz
km	kilometer, kilometers
kn	knot, knots
L	latitude
L	lower limb correction for moon
l	difference of latitude
l	logarithm, logarithmic
LAN	local apparent noon
LANBY	large automatic navigational buoy
LASH	lighter aboard ship
LAT	local apparent time
lat.	latitude
LF	low frequency
L.Fl.	long flashing
LHA	local hour angle
LHW	ower high water
LHWI	lower high water interval
LL	lower limb
LLW	lower low water
LLWD	lower low water datum
LLWI	lower low water interval
Lm	middle latitude
Lm	mean latitude
LMT	local mean time
LNB	large navigational buoy
LNG	liquified natural gas
LPG	liquified petroleum gas
Log	logarithm, logarithmic
Loge	natural logarithm (to the base e)
Log10	common logarithm (to the base 10)
Long.	longitude>
LOP	line of position
LST	local sidereal time
Lt.	light
Lt Ho	light house
Lt V	light vessel
LW	low water
LWD	low water datum
LWI	low water interval
LWI	mean low water lunitidal interval
LWQ	tropic low water inequality

M

M	celestial body
M	meridian (upper branch)
M	magnetic (direction)
M	meridional parts
M	nautical mile, miles
M	other ship
m	meridian (lower branch)
m	meridional difference
m	meter,(s)
m	U.S. survey mile, miles
m	end of other ship’s true vector
m	minutes
mag.	magnetic
mag.	magnitude
MARAD	United States Maritime Administration
MB	magnetic bearing
mb	millibar(s)
MC	magnetic course
mc	megacycle, megacycles
mc	megacycles per second
MC&G	mapping, charting and geodesy
MCPA	minutes to closest point of approach
Mer. Pass.	meridian passage
MF	medium frequency
MGRS	military grid reference system
MH	magnetic heading
MHHW	mean higher high water
MHHWL	mean higher high water line
MHW	mean high water
MHWI	mean high water lunitidal interval
MHWL	mean high water line
MHWN	neap high water or high water neaps
MHWS	mean high water springs
MHz	megahertz
mi.	mile, miles
mid	middle
min.	minute(s)
MLLW	mean lower low water
MLLWL	mean lower low water line
MLW	mean low water
MLWI	mean low water lunitidal interval
MLWL	mean low water line
MLWN	neap low water or low water neaps
MLWS	mean low water springs
mm	millimeters
Mn	mean range of tide
mo	month(s)
MODU	mobile offshore drilling unit
Mon	monument
Mo.(U)	Morse Uniform (light)
mph	miles per hour
MPP	most probable position
MRI	mean rise interval
MRM	miles of relative movement
ms	millisecond(s)
MSC	Military Sealift Command
MSI	maritime safety information
MSL	mean sea level
MTI	moving target indication
MTL	mean tide level
MWL	mean water level
MWLL	mean water level line
MZn	magnetic azimuth

N

N	north
N	nun
n	natural (trigonometric function)
Na	nadir
NAD	North American Datum
NASA	National Aeronautics and Space Administration
NAUTO	nautophone
NAVSAT	Navy Navigation Satellite System
NAVSSI	navigation sensor system interface
NBDP	narrow band direct printing
NBS	National Bureau of Standards
NCS	network coordination station
NESS	National Earth Satellite Service
NGVD	National Geodetic Vertical Datum
NLT	not less than (used with danger bearing)
n. mi.	nautical mile(s)
NM	nautical mile, miles
NM	notice to mariners
NMEA	National Marine Electronics Association
NMT	not more than (used with danger bearing)
NNSS	Navy Navigation Satellite System
NOAA	National Oceanic and Atmospheric Administration
NOS	National Ocean Service
NRML	new relative movement line
NtM	notice to mariners
NWS	National Weather Service

O

Obsc	obscured
Obs Spot	Observation spot
Obstr	obstruction
Oc.	occulting
Oc.(2)	group occulting
Oc.(2+1)	composite group occulting
Occas	occasional
ODAS	oceanographic data acquisition systems
Or	orange
OTC	officer in tactical command
OTSR	Optimum Track Ship Routing

P

P	atmospheric pressure
P	parallax
P	planet
P	pole
P	pillar
p	departure
p	polar distance
PA	position approximate
PC	personal correction
PC	personal computer
PD	position doubtful
PCA	polar cap absorption
PCD	polar cap disturbance
PCP	potential point of collisio
pgc	per gyrocompass
P in A	parallax in altitude
PM	pulse modulation
PM	post meridian (after noon)
Pn	north pole
Pn	north celestial pole
PPC	predicted propagation correction
PPDB	point positioning data base
PPI	plan position indicator
PRF	>pulse repetition frequency
Priv	private
Priv	privately
PROHIB	prohibited
PRR	pulse repetition rate
Ps	south pole
Ps	south celestial pole
psc	per standard compass
p stg c	per steering compass
Pub.	publication
PV	prime vertical
Pyl	pylon

Q

Q	quick flashing
Q(3)	group quick flashing (3 flashes)
Q(6)+L.Fl.	group quick flashing (6 flashes) plus a long flash
Q	Polaris correction
QQ'	celestial equator

R

r	end of own ship’s true vector
R	Rankine (temperature)
R	refraction
R	own ship
R	red
R	rocky
R	coast radio station
RA	right ascension
RACON	radar transponder beacon
rad	radian(s)
RB	relative bearing
R Bn	radiobeacon
RCC	Rescue Coordination Center
RDF	radio direction finder
RDF	RDF station
Rep.	reported
rev.	reversed
RF (rf)	radio frequency
R Fix	running fix
rk	rock, rocky
RLG	ring laser gyro
rm	relative DRM-SRM vector
R Mast	radio mast
RORO	roll-on/roll-off
RML	relative movement line
RMS	root mean square
RSS	root sum square
RTCM	Radio Technical Commission for Maritime Services
RZn	relative azimuth

S

s	second(s)
S	sea-air temperature difference correction
S	slow
S	south
S	set
S	speed
S	sand
SALM	single anchor leg mooring
SAM	system area monitor
SAR	search and rescue
SART	search and rescue radar transponder
SBM	single buoy mooring
SD	semidiameter
SD	sounding doubtful
sec	secant
sec.	second, seconds
semidur.	semiduration
SENC	system electronic navigation chart
SES	ship earth station
SF	Secondary Phase Factor
SH	ship’s head (heading)
SHA	sidereal hour angle
SHF	super high frequency
SI	International System of Units
SID	sudden ionospheric disturbance
sin	sine
SINS	Ships Inertial Navigation System
SLD	sea level datum
SMG	speed made good
SNR	signal-to-noise ratio
SOA	speed of advance
SOG	speed over ground
SOLAS	Safety of Life at Sea Convention
SP	spire
SP	spherical
SPA	sudden phase anomaly
SPM	single point mooring
SRM	speed of relative movement
SS	signal station
U.S. Sur M	U.S. Survey mile(s)
sub, subm	submerged

T

T	air temperature correction (altitude)
T	table
T	temperature
T	time
T	toward (altitude intercept)
T	true (direction)
t	dry-bulb temperature
t	elapsed time
t	meridian angle
t'	wet-bulb temperature
tab.	table
TAI	International Atomic Time
tan	tangent
TB	true bearing
TB	turning bearing
TB	air temperature atmospheric pressure correction (altitude)
TC	true course
TCA	time of satellite closest approach
TCPA	time to closest point of approach
TcHHW	tropic higher high water
TcHHWI	tropic higher high water interval
TcHLW	tropic higher low water
TcLHW	tropic lower high water
TcLLW	tropic lower low water
TcLLWI	tropic lower low water interval
TD	time difference (Loran C)
Tel	telephone
Tel	telegraph
TG	time difference of groundwaves from master and secondary (slave) stations (Loran)
TGS	time difference of groundwave from master and skywave from secondary (slave) station (Loran)
TH	true heading
TMG	track made good
TOD	time of day (clock)
Tk	tank
TR	track
Tr	transit
Tr	tower
Ts	time difference of skywaves from master and secondary (slave) stations (Loran)
TSG	time difference of skywave from master and groundwave from secondary (slave) station (Loran)
TSS	traffic separation scheme
TZn	true azimuth

U

U	upper limb correction for moon
UHF	ultra high frequency
UL	upper limb
Uncov	uncovers
UPS	Universal Polar Stereographic
U.Q.	ultra quick flashing
USGS	United States Geodetic Survey
USWMS	Uniform State Waterway Marking System
UT	Universal Time
UT0	Universal Time 0
UTl	Universal Time 1
UT2	Universal Time 2
UTC	Coordinated Universal Time
UTM	Universal Transverse Mercator

V

V	variation
V	vertex
v	excess of GHA change from adopted value for 1 hour
var.	variation
vel	velocity
Ver	vertical
VHF	very high frequency
VHSD	very high speed data
Vi	violet
VLCC	very large crude carrier
VLF	very low frequency
vol	volcano
vol	volcanic
VPF XX	vector product format
V.Q.	very quick flashing
V.Q.(3)	group very quick flashing
VRM	variable range marker
VTS	vessel traffic service

W

W	west; white
WARC	World Administrative Radio Council
WE	watch error
WGS	World Geodetic System
Wk	wreck
WMO	World Meteorological Organization
WWNWS	World Wide Navigational Warning Service
WT	watch time

X – Y – Z

X	parallactic angle
XMTR	transmitter
y.	yellow
yd(s).	yard(s)
yr(s).	year(s)
z	zenith distance
Z	azimuth angle; zenith
ZD	zone description
Z Diff.	azimuth
Znpgc	azimuth per gyrocompass