Glossary of Military Terms
The time required for the activity of a given
radioactive species to decrease to half of its initial value due
to radioactive decay. The half-life is a characteristic property
of each radioactive species and is independent of its amount or
condition. The effective half-life of a given isotope is the
time in which the quantity in the body will decrease to half as
a result of both radioactive decay and biological elimination.
As applied to delayed fallout, it is the time
required for the amount of weapon debris deposited in a
particular part of the atmosphere to decrease to half of its
Thickness of absorbing material necessary to reduce
by one-half the intensity of radiation which passes through it.
Applies to those individuals who engage in the breakout,
lifting, or repositioning of ordnance or explosive devices in
order to facilitate storage or stowage, assembly or disassembly,
loading or downloading, or transporting. See also assembly;
downloading; loading; ordnance.
The passing of control authority of an aircraft from one
control agency to another control agency. Handover action may be
accomplished between control agencies of separate Services when
conducting joint operations or between control agencies within a
single command and control system. Handover action is complete
when the receiving controller acknowledges assumption of control
authority. Also called hand-off.
In evasion and recovery operations, the transfer of
evaders between two recovery forces. See also evader; evasion;
evasion and recovery; recovery; recovery operations.
A control feature, preferably following easily
defined terrain features, at which responsibility for the
conduct of combat operations is passed from one force to
A malfunction that causes an undesired delay in the
functioning of a firing system.
Fire designed to disturb the rest of the enemy
troops, to curtail movement, and, by threat of losses, to lower
morale. See also fire.
An incident in which the primary objective is to disrupt
the activities of a unit, installation, or ship, rather than to
inflict serious casualties or damage.
A restricted body of water, an anchorage, or other limited
coastal water area and its mineable water approaches, from which
shipping operations are projected or supported. Generally, a
harbor is part of a base, in which case the harbor defense force
forms a component element of the base defense force established
for the local defense of the base and its included harbor.
The defense of a harbor or anchorage and its water
approaches against external threats such as: a. submarine,
submarine-borne, or small surface craft attack; b. enemy
minelaying operations; and c. sabotage. The defense of a harbor
from guided missiles while such missiles are airborne is
considered to be a part of air defense. See also port security.
A portion of a beach especially prepared with a hard
surface extending into the water, employed for the purpose of
loading or unloading directly into or from landing ships or
A site, normally constructed under rock or concrete
cover, designed to provide protection against the effects of
conventional weapons. It may also be equipped to provide
protection against the side effects of a nuclear attack and
against a chemical or a biological attack.
hard missile base
A launching base that is protected against a nuclear
1. A paved or stabilized area where vehicles are
parked. 2. Open ground area having a prepared surface and used
for the storage of materiel.
1. The generic term dealing with physical items as
distinguished from its capability or function such as equipment,
tools, implements, instruments, devices, sets, fittings,
trimmings, assemblies, subassemblies, components, and parts. The
term is often used in regard to the stage of development, as in
the passage of a device or component from the design stage into
the hardware stage as the finished object. 2. In data
automation, the physical equipment or devices forming a computer
and peripheral components. See also software.
The process and/or results of adjusting differences or
inconsistencies to bring significant features into agreement.
In land operations, an attack in which preparation
time is traded for speed in order to exploit an opportunity. See
also deliberate attack.
The rapid creation of a route through a minefield,
barrier, or fortification by any expedient method.
hasty breaching (land mine warfare)
The creation of lanes through enemy minefields by
expedient methods such as blasting with demolitions, pushing
rollers or disabled vehicles through the minefields when the
time factor does not permit detailed reconnaissance, deliberate
breaching, or bypassing the obstacle.
The crossing of an inland water obstacle using the
crossing means at hand or those readily available, and made
without pausing for elaborate preparations. See also deliberate
A defense normally organized while in contact with
the enemy or when contact is imminent and time available for the
organization is limited. It is characterized by improvement of
the natural defensive strength of the terrain by utilization of
foxholes, emplacements, and obstacles. See also deliberate
An opening in a ship's deck giving access to cargo holds.
A list showing, for each hold section of a cargo ship, a
description of the items stowed, their volume and weight, the
consignee of each, and the total volume and weight of materiel
in the hold.
See moving havens.
A condition with the potential to cause injury, illness,
or death of personnel; damage to or loss of equipment or
property; or mission degradation. See also injury; risk.
hazards of electromagnetic radiation to ordnance
The danger of accidental actuation of electro-explosive
devices or otherwise electrically activating ordnance because of
radio frequency electromagnetic fields. This unintended
actuation could have safety (premature firing) or reliability
(dudding) consequences. Also called HERO. See also
electromagnetic radiation; HERO SAFE ordnance; HERO UNSAFE
heading hold mode
In a flight control system, a control mode that
automatically maintains an aircraft heading that exists at the
instant of completion of a maneuver.
An instrument which displays heading transmitted
electrically from a remote compass system.
heading select feature
A flight control system feature that permits selection or
preselection of desired automatically controlled heading or
headings of an aircraft.
(DOD,NATO) A display of flight, navigation, attack, or other
information superimposed upon the pilot's forward field of view.
Also called HUD. See also flight; horizontal situation display.
health service logistic support
A functional area of logistic support that supports the
joint force surgeon's health service support mission. It
includes supplying Class VIII medical supplies (medical materiel
to include medical peculiar repair parts used to sustain the
health service support system), optical fabrication, medical
equipment maintenance, blood storage and distribution, and
medical gases. Also called HSLS. See also health service
support; joint force surgeon.
health service support
All services performed, provided, or arranged by the
Services to promote, improve, conserve, or restore the mental or
physical well-being of personnel. These services include, but
are not limited to, the management of health services resources,
such as manpower, monies, and facilities; preventive and
curative health measures; evacuation of the wounded, injured, or
sick; selection of the medically fit and disposition of the
medically unfit; blood management; medical supply, equipment,
and maintenance thereof; combat stress control; and medical,
dental, veterinary, laboratory, optometric, medical food, and
medical intelligence services. Also called HSS.
A composite of ongoing or potential enemy actions;
environmental, occupational, and geographic and meteorological
conditions; endemic diseases; and employment of nuclear,
biological, and chemical weapons (to include weapons of mass
destruction) that can reduce the effectiveness of joint forces
through wounds, injuries, illness, and psychological stressors.
heavy antitank weapon
A weapon capable of operating from ground or vehicle, used
to defeat armor and other material targets.
See field artillery.
A system of delivery of heavy supplies and equipment by
1. Any single cargo lift, weighing over 5 long tons, and
to be handled aboard ship. 2. In Marine Corps usage, individual
units of cargo that exceed 800 pounds in weight or 100 cubic
feet in volume.
A ship specially designed and capable of loading and
unloading heavy and bulky items. It has booms of sufficient
capacity to accommodate a single lift of 100 tons.
See altitude datum.
See altitude delay.
See altitude hole.
height of burst
The vertical distance from the Earth's surface or
target to the point of burst. Also called HOB. See also optimum
height of burst; safe burst height; types of burst.
helicopter assault force
A task organization combining helicopters,
supporting units, and helicopter-borne troop units for use in
helicopter-borne assault operations.
helicopter control station
A shipboard aircraft control tower or, on ships not
equipped with a control tower, the communications installation
that serves as such. On all Coast Guard cutters, the helicopter
control station is located in the pilot house. Also called HCS.
See also station.
helicopter direction center
In amphibious operations, the primary direct control
agency for the helicopter group/unit commander operating under
the overall control of the tactical air control center.
helicopter drop point
A designated point within a landing zone where helicopters
are unable to land because of the terrain, but in which they can
discharge cargo or troops while hovering.
helicopter landing site
A designated subdivision of a helicopter landing zone in
which a single flight or wave of assault helicopters land to
embark or disembark troops and/or cargo.
helicopter landing zone
A specified ground area for landing assault helicopters to
embark or disembark troops and/or cargo. A landing zone may
contain one or more landing sites. Also called HLZ.
A safety air corridor in which helicopters fly to or
from their destination during helicopter operations. See also
helicopter retirement route.
helicopter retirement route
The track or series of tracks along which
helicopters move from a specific landing site or landing zone.
See also helicopter lane.
helicopter support team
A task organization formed and equipped for
employment in a landing zone to facilitate the landing and
movement of helicopter-borne troops, equipment, and supplies,
and to evacuate selected casualties and enemy prisoners of war.
Also called HST.
helicopter transport area
Areas to the seaward and on the flanks of the outer
transport and landing ship areas, but preferably inside the area
screen, used for launching and/or recovering helicopters.
A prepared area designated and used for takeoff and
landing of helicopters. (Includes touchdown or hover point.)
A facility designated for operating, basing,
servicing, and maintaining helicopters.
A chemical compound that will kill or damage plants.
HERO SAFE ordnance
Any ordnance item that is percussion initiated,
sufficiently shielded or otherwise so protected that all
electro-explosive devices contained by the item are immune to
adverse effects (safety or reliability) when the item is
employed in its expected radio frequency environments, provided
that the general hazards of electromagnetic radiation to
ordnance requirements defined in the hazards from
electromagnetic radiation manual are observed. See also
electromagnetic radiation; hazards of electromagnetic radiation
to ordnance; HERO SUSCEPTIBLE ordnance; HERO UNSAFE ordnance;
HERO SUSCEPTIBLE ordnance
Any ordnance item containing electro-explosive devices
proven by test or analysis to be adversely affected by radio
frequency energy to the point that the safety and/or reliability
of the system is in jeopardy when the system is employed in its
expected radio frequency environment. See also electromagnetic
radiation; hazards of electrogagnetic radiation to ordnance;
HERO SAFE ordnance; HERO UNSAFE ordnance; ordnance.
HERO UNSAFE ordnance
Any ordnance item containing electro-explosive devices
that has not been classified as HERO SAFE or HERO SUSCEPTIBLE
ordnance as a result of a hazards of electromagnetic radiation
to ordnance (HERO) analysis or test is considered HERO UNSAFE
ordnance. Additionally, any ordnance item containing
electro-explosive devices (including those previously classified
as HERO SAFE or HERO SUSCEPTIBLE ordnance) that has its internal
wiring exposed; when tests are being conducted on that item that
result in additional electrical connections to the item; when
electro-explosive devices having exposed wire leads are present
and handled or loaded in any but the tested condition; when the
item is being assembled or disassembled; or when such ordnance
items are damaged causing exposure of internal wiring or
components or destroying engineered HERO protective devices. See
also electromagnetic radiation; hazards of electromagnetic
radiation to ordnance; HERO SAFE ordnance; HERO SUSCEPTIBLE
See chemical horn.
The fallout safe height of burst for a nuclear weapon that
increases damage to or casualties on soft targets, or reduces
induced radiation contamination at actual ground zero. See also
types of burst.
high altitude bombing
Horizontal bombing with the height of release over 15,000
high altitude burst
The explosion of a nuclear weapon which takes place
at a height in excess of 100,000 feet (30,000 meters). Also
called HAB. See also types of burst.
high-altitude low-opening parachute technique
A method of delivering personnel, equipment, or supplies
from airlift aircraft that must fly at altitudes above the
threat umbrella. Also called HALO.
high-altitude missile engagement zone
See weapon engagement zone.
In artillery and naval gunfire support, an order or
request to obtain high angle fire.
high angle fire
Fire delivered at angles of elevation greater than
the elevation that corresponds to the maximum range of the gun
and ammunition concerned; fire, the range of which decreases as
the angle of elevation is increased.
high-density airspace control zone
Airspace designated in an airspace control plan or
airspace control order, in which there is a concentrated
employment of numerous and varied weapons and airspace users. A
high-density airspace control zone has defined dimensions which
usually coincide with geographical features or navigational
aids. Access to a high-density airspace control zone is normally
controlled by the maneuver commander. The maneuver commander can
also direct a more restrictive weapons status within the
high-density airspace control zone. Also called HIDACZ.
high explosive cargo
Cargo such as artillery ammunition, bombs, depth charges,
demolition material, rockets, and missiles.
See oblique air photograph.
A target whose loss to the enemy will significantly
contribute to the success of the friendly course of action.
High-payoff targets are those high-value targets that must be
acquired and successfully attacked for the success of the
friendly commander's mission. Also called HPT. See also
high-value target; target.
high-payoff target list
A prioritized list of high-payoff targets by phase of the
joint operation. Also called HPTL. See also high-payoff target;
US personnel whose position or assignment makes them
particularly vulnerable to capture by hostile forces in combat,
by terrorists, or by unfriendly governments. See also hostile;
Personnel who, by their grade, assignment, symbolic value,
or relative isolation, are likely to be attractive or accessible
terrorist targets. See also antiterrorism.
high value airborne asset protection
A defensive counterair mission that defends airborne
national assets which are so important that the loss of even one
could seriously impact US warfighting capabilities or provide
the enemy with significant propaganda value. Examples of high
value airborne assets are Airborne Warning and Control System,
Rivet Joint, Joint Surveillance and Target Attack Radar System,
and Compass Call. Also called HVAA protection. See also
high value asset control items
Items of supply identified for intensive management
control under approved inventory management techniques designed
to maintain an optimum inventory level of high investment items.
Also called hi-value asset control items.
A target the enemy commander requires for the successful
completion of the mission. The loss of high-value targets would
be expected to seriously degrade important enemy functions
throughout the friendly commander's area of interest. Also
called HVT. See also high-payoff target; target.
high velocity drop
A drop procedure in which the drop velocity is
greater than 30 feet per second (low velocity drop) and lower
than free drop velocity. See also airdrop.
Properly, a mark left on a beach by wave wash at the
preceding high water. It does not necessarily correspond to the
high-water line. Because it can be determined by simple
observation, it is frequently used in place of the high-water
line, which can be determined only by a survey. When so used, it
is called the high-water line.
A method of representing relief on a map by
depicting the shadows that would be cast by high ground if light
were shining from a certain direction.
That region surrounding a beach or terminal operation to
the extent that it has characteristics that affect the
operation--normally within 100 miles.
The area of land within an operational area of a specific
beach or terminal operation--usually within 5 miles.
hi-value asset control item
See high value asset control items.
In helicopters, the mechanism by which external
loads may be raised or lowered vertically.
1. A cargo stowage compartment aboard ship. 2. To
maintain or retain possession of by force, as a position or an
area. 3. In an attack, to exert sufficient pressure to prevent
movement or redisposition of enemy forces. 4. As applied to air
traffic, to keep an aircraft within a specified space or
location which is identified by visual or other means in
accordance with Air Traffic Control instructions. See also fix;
An anchorage where ships may lie: a. if the assembly
or working anchorage, or port, to which they have been assigned
is full; b. when delayed by enemy threats or other factors from
proceeding immediately on their next voyage; c. when dispersed
from a port to avoid the effects of a nuclear attack. See also
assembly anchorage; emergency anchorage; working anchorage.
An attack designed to hold the enemy in position, to
deceive the enemy as to where the main attack is being made, to
prevent the enemy from reinforcing the elements opposing the
main attack, and/or to cause the enemy to commit the reserves
prematurely at an indecisive location.
A geographically or electronically defined location
used in stationing aircraft in flight in a predetermined pattern
in accordance with air traffic control clearance. See also orbit
A specified location on the airfield, close to the
active runway and identified by visual means, at which the
position of a taxiing aircraft is maintained in accordance with
air traffic control instructions.
A shaped charge producing a deep cylindrical hole of
relatively small diameter in the direction of its axis of
home recovery mission profile
A mission profile that involves the recovery of an
aircraft at its permanent or temporarily assigned operating
The permanent location of active duty units and Reserve
Component units (e.g., location of armory or reserve center).
See also active duty; Reserve Components.
The technique whereby a mobile station directs
itself, or is directed, towards a source of primary or reflected
energy, or to a specified point.
A system by which a missile or torpedo steers itself
towards a target by means of a self-contained mechanism which is
activated by some distinguishing characteristics of the target.
See also active homing guidance; passive homing guidance;
semi-active homing guidance.
In naval mine warfare, a mine fitted with propulsion
equipment which homes on to a target. See also mine.
In general, the apparent or visible junction of the Earth
and sky, as seen from any specific position. Also called the
apparent, visible, or local horizon. A horizontal plane passing
through a point of vision or perspective center. The apparent or
visible horizon approximates the true horizon only when the
point of vision is very close to sea level.
horizontal action mine
In land mine warfare, a mine designed to produce a
destructive effect in a plane approximately parallel to the
The error in range, deflection, or in radius, which
a weapon may be expected to exceed as often as not. Horizontal
error of weapons making a nearly vertical approach to the target
is described in terms of circular error probable. Horizontal
error of weapons producing elliptical dispersion pattern is
expressed in terms of probable error. See also circular error
probable; delivery error; deviation; dispersion error.
Loading of items of like character in horizontal
layers throughout the holds of a ship. See also loading.
horizontal situation display
An electronically generated display on which
navigation information and stored mission and procedural data
can be presented. Radar information and television picture can
also be displayed either as a map overlay or as a separate
image. See also head-up display.
horizontal situation indicator
An instrument which may display bearing and distance
to a navigation aid, magnetic heading, track/course and
The lateral distribution of unit equipment or categories
of supplies so that they can be unloaded simultaneously from two
or more holds.
In naval mine warfare, a projection from the mine
shell of some contact mines which, when broken or bent by
contact, causes the mine to fire.
A medical treatment facility capable of providing
inpatient care. It is appropriately staffed and equipped to
provide diagnostic and therapeutic services, as well as the
necessary supporting services required to perform its assigned
mission and functions. A hospital may, in addition, discharge
the functions of a clinic.
A person held as a pledge that certain terms or agreements
will be kept. (The taking of hostages is forbidden under the
Geneva Conventions, 1949.)
A nation in which representatives or organizations of
another state are present because of government invitation
and/or international agreement.
In combat and combat support operations, an identity
applied to a track declared to belong to any opposing nation,
party, group, or entity, which by virtue of its behavior or
information collected on it such as characteristics, origin, or
nationality contributes to the threat to friendly forces. See
also neutral; suspect; unknown.
1. A hostile act is an attack or other use of force by any
civilian, paramilitary, or military force or terrorist(s) (with
or without national designation) against the United States, US
forces and, in certain circumstances, US nationals, their
property, US commercial assets, or other designated non-US
forces, foreign nationals, and their property. 2. Force used
directly to preclude or impede the mission and/or duties of US
forces, including the recovery of US personnel and vital US
Government property. When a hostile act is in progress the right
exists to use proportional force, including armed force, in
self-defense by all necessary means available to deter or
neutralize the potential attacker or, if necessary, to destroy
A person who is the victim of a terrorist activity or who
becomes a casualty "in action." "In action" characterizes the
casualty as having been the direct result of hostile action,
sustained in combat or relating thereto, or sustained going to
or returning from a combat mission provided that the occurrence
was directly related to hostile action. Included are persons
killed or wounded mistakenly or accidentally by friendly fire
directed at a hostile force or what is thought to be a hostile
force. However, not to be considered as sustained in action and
not to be interpreted as hostile casualties are injuries or
death due to the elements, self-inflicted wounds, combat
fatigue, and except in unusual cases, wounds or death inflicted
by a friendly force while the individual is in an
absent-without-leave, deserter, or dropped-from-rolls status or
is voluntarily absent from a place of duty. See also casualty;
casualty type; nonhostile casualty.
See operational environment.
Any civilian, paramilitary, or military force or
terrorist(s), with or without national designation, that have
committed a hostile act, exhibited hostile intent, or have been
declared hostile by appropriate US authority.
The threat of imminent use of force by a foreign force,
terrorist(s), or organization against the United States and US
national interests, US forces and, in certain circumstances, US
nationals, their property, US commercial assets, and other
designated non-US forces, foreign nationals, and their property.
When hostile intent is present, the right exists to use
proportional force, including armed force, in self-defense by
all necessary means available to deter or neutralize the
potential attacker or, if necessary, to destroy the threat. A
determination that hostile intent exists and requires the use of
proportional force in self-defense must be based on evidence
that an attack is imminent. Evidence necessary to determine
hostile intent will vary depending on the state of international
and regional political tension, military preparations,
intelligence, and indications and warning information.
A nation that receives the forces and/or supplies of
allied nations, coalition partners, and/or NATO organizations to
be located on, to operate in, or to transit through its
territory. Also called HN.
Civil and/or military assistance rendered by a nation to
foreign forces within its territory during peacetime, crises or
emergencies, or war based on agreements mutually concluded
between nations. Also called HNS. See also host nation.
host-nation support agreement
Basic agreement normally concluded at
government-to-government or government-to-combatant commander
level. These agreements may include general agreements, umbrella
agreements, and memoranda of understanding. See also host
nation; host-nation support.
hot photo interpretation report
A preliminary unformatted report of significant
information from tactical reconnaissance imagery dispatched
prior to compilation of the initial photo interpretation report.
It should pertain to a single objective, event, or activity of
significant interest to justify immediate reporting. Also called
Pursuit commenced within the territory, internal waters,
the archipelagic waters, the territorial sea, or territorial
airspace of the pursuing state and continued without
interruption beyond the territory, territorial sea, or airspace.
Hot pursuit also exists if pursuit commences within the
contiguous or exclusive economic zones or on the continental
shelf of the pursuing state, continues without interruption, and
is undertaken based on a violation of the rights for the
protection of which the zone was established. The right of hot
pursuit ceases as soon as the ship or hostile force pursued
enters the territory or territorial sea of its own state or of a
third state. This definition does not imply that force may or
may not be used in connection with hot pursuit. NOTE: This term
applies only to law enforcement activities.
Region in a contaminated area in which the level of
radioactive contamination is considerably greater than in
neighboring regions in the area.
A self-sustaining maneuver whereby a fixed, or
nearly fixed, position is maintained relative to a spot on the
surface of the Earth or underwater.
The highest altitude at which the helicopter is
capable of hovering in standard atmosphere. It is usually stated
in two figures: hovering in ground effect and hovering out of
1. A cannon that combines certain characteristics of guns
and mortars. The howitzer delivers projectiles with medium
velocities, either by low or high trajectories. 2. Normally a
cannon with a tube length of 20 to 30 calibers; however, the
tube length can exceed 30 calibers and still be considered a
howitzer when the high angle fire zoning solution permits range
overlap between charges. See also gun; mortar.
An organization that sorts and distributes inbound cargo
from wholesale supply sources (airlifted, sealifted, and ground
transportable) and/or from within the theater. See also hub and
spoke distribution; spoke.
hub and spoke distribution
A physical distribution system developed and modeled on
industry standards to provide cargo management for a theater. It
is based on a "hub" moving cargo to and between several
"spokes". It is designed to increase transportation efficiencies
and in-transit visibility and reduce order ship time. See also
distribution; distribution system; hub; in-transit visibility;
A category of intelligence derived from information
collected and provided by human sources. Also called HUMINT. See
also human resources intelligence.
humanitarian and civic assistance
Assistance to the local populace provided by predominantly
US forces in conjunction with military operations and exercises.
This assistance is specifically authorized by title 10, United
States Code, section 401, and funded under separate authorities.
Assistance provided under these provisions is limited to (1)
medical, dental, and veterinary care provided in rural areas of
a country; (2) construction of rudimentary surface
transportation systems; (3) well drilling and construction of
basic sanitation facilities; and (4) rudimentary construction
and repair of public facilities. Assistance must fulfill unit
training requirements that incidentally create humanitarian
benefit to the local populace. Also called HCA. See also foreign
humanitarian assistance coordination center
A temporary center established by a geographic combatant
commander to assist with interagency coordination and planning.
A humanitarian assistance coordination center operates during
the early planning and coordination stages of foreign
humanitarian assistance operations by providing the link between
the geographic combatant commander and other United States
Government agencies, nongovernmental organizations, and
international and regional organizations at the strategic level.
Also called HACC. See also foreign humanitarian assistance;
Department of Defense and Department of State program to
promote the foreign policy interests of the United States by
assisting other nations in protecting their populations from
landmines and clearing land of the threat posed by landmines
remaining after conflict has ended. The humanitarian demining
program includes training of host nation deminers, establishment
of national demining organizations, provision of demining
equipment, mine awareness training, and research development.
humanitarian operations center
An interagency policymaking body that coordinates the
overall relief strategy and unity of effort among all
participants in a large foreign humanitarian
assistanceoperation. It normally is established under the
direction of the government of the affected country or the
United Nations, ora United States Government agency during a
United States unilateral operation. The humanitarian operations
center shouldconsist of representatives from the affected
country, the United States Embassy or Consulate, the joint
force, the UnitedNations, nongovernmental and international
organizations, and other major players in the operation. Also
called HOC. See also operation.
human resources intelligence
The intelligence derived from the intelligence collection
discipline that uses human beings as both sources and
collectors, and where the human being is the primary collection
instrument. Also called HUMINT.
Those weapons or stores on an aircraft that the pilot has
attempted to drop or fire but could not because of a malfunction
of the weapon, rack or launcher, or aircraft release and control
In naval mine warfare, the track to be followed by
the hunter (or sweeper) to ensure that the hunting (or sweeping)
gear passes over the lap track.
See thermonuclear weapon.
A nautical chart showing depths of water, nature of
bottom, contours of bottom and coastline, and tides and currents
in a given sea or sea and land area.
Reconnaissance of an area of water to determine depths,
beach gradients, the nature of the bottom, and the location of
coral reefs, rocks, shoals, and manmade obstacles.
The science which deals with the measurements and
description of the physical features of the oceans, seas, lakes,
rivers, and their adjoining coastal areas, with particular
reference to their use for navigational purposes.
A chamber used to induce an increase in ambient
pressure as would occur in descending below sea level, in a
water or air environment. It is the only type of chamber
suitable for use in the treatment of decompression sickness in
flying or diving. Also called compression chamber; diving
chamber; recompression chamber.
hyperbolic navigation system
A radio navigation system which enables the position
of an aircraft equipped with a suitable receiver to be fixed by
two or more intersecting hyperbolic position lines. The system
employs either a time difference measurement of pulse
transmissions or a phase difference measurement of phase-locked
continuous wave transmissions. See also loran.
Fuel which will spontaneously ignite with an
oxidizer, such as aniline with fuming nitric acid. It is used as
the propulsion agent in certain missile systems.
Of or pertaining to speeds equal to, or in excess
of, five times the speed of sound. See also speed of sound.
Term used to describe the imagery derived from subdividing
the electromagnetic spectrum into very narrow bandwidths. These
narrow bandwidths may be combined with or subtracted from each
other in various ways to form images useful in precise terrain
or target analysis. Also called HSI.
Stereoscopic viewing in which the relief effect is
noticeably exaggerated, caused by the extension of the camera
base. Also called exaggerated stereoscopy.
A chamber used to induce a decrease in ambient
pressure as would occur in ascending to altitude. This type of
chamber is primarily used for training and experimental
purposes. Also called altitude chamber; decompression chamber.
A method of showing relief on maps and charts by
coloring in different shades those parts which lie between
selected levels. Also called altitude tint; elevation tint;