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Glossary of Terms

AH-1G, AH-IJ:
The armed version of the UH-1 helicopter. The initial Marine AH-1s were Army G models modified only with Navy compatible radios, Marine green paint and a rotor brake for shipboard operations. Later Marine models such as the AH-1J were specifically designed for Marine aviation requirements and were twin-engined.

AO:
Arial Observer – usually assigned to fly in second seat for Aerial Observation – primarily assigned from infantry, artillery, or intelligence billets.

AO:
Area of operations, similar in definition to TAOR discussed below.

ARVN:
Army of the Republic of Viet Nam.

BDA:
Bomb Damage Assessment – given to fixed wing pilot by airborne AO at end of air to ground support mission.

BDE:
The abbreviation for a US Army brigade.

BLT:
Battalion Landing Team, a US Marine infantry battalion specifically task organized and equipped to conduct amphibious or helicopter-borne landings from the sea.

BOMB:
MK-81 – 250# LDGP bomb
MK-82 – 500# LDGP Bomb
MK-83 – 1000# LDGP Bomb
MK-84 – 2000# LDGP Bomb (bunker buster)
The MK 80 series Low Drag General Purpose (LDGP) bombs are used in the majority of bombing operations where maximum blast and explosive effects are desired. LDGP bombs are designed to be aerodynamically streamlined. Their cases are relatively light and approximately 45 percent of their complete weight is explosive. General purpose bombs may use both nose and tail fuses and conical or retarded tail fins. Snakeye was fielded in 1964 and used extensively since; the retarder tail (Mk 14 fins for Mk 81 250-pound) allowed low-level, high-precision attack while avoiding bomb-fragment damage to delivery aircraft and retaining a low-drag delivery option. Normal fuses are the mechanical M904 (nose) and the M905 (tail).

BLU-32 Napalm
These 500 lb class stores happen to be finned which allowed for a more accurate and predictable trajectory. If the fins were removed, the canisters would tumble unpredictably after release which created a wider dispersion pattern for the napalm. Napalm was used as an incendiary type weapon.

MK-20 – Rockeye
The MK-20 Rockeye is a free-fall, unguided cluster weapon designed to kill tanks and armored vehicles. The system consists of a clamshell dispenser, a mechanical MK-339 timed fuse, and 247 dual-purpose armor-piercing shaped-charge bomblets. The bomblet weighs 1.32 pounds and has a 0.4-pound shaped-charge warhead of high explosives, which produces up to 250,000 psi at the point of impact, allowing penetration of approximately 7.5 inches of armor. Rockeye is most efficiently used against area targets requiring penetration to kill.

MK-36 – Destructor Mine
Destructor Mines are general purpose low-drag bombs converted to mines. They can be deployed by air, either at sea as bottom mines or on land as land mines. With the MK 75 Modification Kit installed, a MK 82 bomb (500 pounds) becomes a MK 36 DST.
The conflict in Southeast Asia saw the introduction of a different kind of mine called a Destructor (DST). Destructors Mk 36, Mk 40, and Mk 41 are aircraft-laid bottom mines which use General Purpose (GP) Low-Drag Bombs Mk 82, Mk 83, and Mk 84, respectively as the mine case and explosive charge. The bombs are converted to mines with the installation of a kit of modular components that comprise a mine-type arming, detector, and firing system. The kit contains an arming device, an explosive booster, a magnetic-influence firing mechanism and associated hardware. The arming device and booster install in the bomb’s nose cavity and the firing-mechanism (with battery) installs in the bomb�s tail cavity. The same kit of components and method of assembly are used for each one of the destructors, but the kits are available in a number of configurations, each with a different circuitry to meet a variety of operational requirements. It should be noted, however, that since the bomb cases are small, medium, and large, they require different flight gear. DST’s became the first mines to be used on both land and sea. When dropped on land, they bury themselves in the ground on impact, ready to be actuated by military equipment, motor vehicles and personnel. When dropped in rivers, canals, channels, and harbors, they lie on the bottom ready to be actuated by a variety of vessels including war ships, freighters, coastal ships, and small craft.

MK-45 – Parachute Flare
The aircraft-launched Mk 45 Mod 0 aircraft parachute flare is used for night illumination of surface areas in search-and-attack operations. It replaces the Mk 24 Mods aircraft parachute flare.
The Mk 45 Mod 0 aircraft parachute flare is as an AUR, complete with the candle, parachute assembly, and fuse. All components are encased in a cylindrical aluminum body approximately 36 inches long (including the fuse assembly) and 4.9 inches in diameter.

The Mk 364 Mod 0 fuse is shipped installed in the flare. Its sole purpose is to control the altitude of flare ejection in relation to launch altitude. It does not directly control candle ignition. The fuse has 15 functional settings and 1 SAFE setting. The functional settings are at 1,000-foot intervals from 1,000 to 14,000 feet, except that 1 minimum setting of 500 feet is provided. The fuse-setting mechanism consists of a single yellow dial indicator you can easily turn by hand-clockwise for setting and counterclockwise for safing. A spring-loaded detent holds the dial indicator at a selected setting or at SAFE, and prevents accidental changing of the setting by vibration forces.

CBU-24B Cluster Bomb Unit
Cluster munitions (CBUs) fall into the dumb bomb or unguided category with the exception of sensor fused weapons. CBUs combine dispensers, fuses, and submunitions into a single weapon with a specialized or general purpose mission. Once released, CBUs fall for a specified amount of time or distance before their dispensers open, allowing the submunitions to effectively cover a wide area target. The submunitions are activated by an internal fuse, and can detonate above ground, at impact, or in a delayed mode.
CH-37C:
Powered with twin reciprocating engines, this heavy helicopter operated on a limited basis in the early years of the war, mainly for the retrieval of downed aircraft.

CH-46A, CH-46D:
A twin gas turbine powered medium helicopter that replaced the UH-34D for troop and cargo lift, medevac, and other assigned missions.

CH-53A, CH-53D:
A twin gas turbine powered heavy helicopter that replaced the CH-37C for the retrieval of downed aircraft, as well as the movement of heavy and large items of equipment such as trucks and artillery. The CH-53D was the improved version with more powerful engines.

CHARLEY RIDGE:
A prominent ridge of mountainous terrain approximately 20 miles southwest of Da Nang that afforded the Viet Cong, also known as “Charley,” a route from Laos into the Da Nang area. It was the site of many Marine operations aimed at disrupting Charley’s movement of men and supplies.

CHINOOK:
The generic name or nickname of the US Army’s CH-47 heavy helicopter.

CIDG:
Civil Indigenous Defense Group, a paramilitary, militia-type unit made up of local Vietnamese who participated in the defense of their own village or hamlet.

CO:
The Commanding Officer, or Commander of a specific unit.

CP:
Command Post, the location from which the CO commanded his unit. This could range from an extensive permanent building complex to a hole in the ground.

D/CS:
Deputy Chief of Staff. The staff officer responsible for a specific function such as D/CS AIR (Aviation) at Headquarters, US Marine Corps, responsible for all aviation matters.

DET:
Abbreviation for detachment, usually a parent organization’s smaller detached unit capable of self-sustained operations. For example, DET, HMH-463 would indicate a small number (4-6) of CH-53 helicopters operating independently of the parent unit, HMH-463.

DMZ:
The Demilitarized Zone separating North and South Viet Nam that was established by the United Nations at the time French IndoChina was partitioned into the two countries. It was generally ignored by both sides during the war.

EAGLE FLIGHT:
(also PACIFIER, KINGFISHER, SPARROWHAWK) A package of aircraft, on either ground or airborne alert, designated to respond to emergency situations or targets of opportunity by either inserting ground units or attacking by fire or both. The group usually consisted of a command helicopter, troop lift helicopters and attack helicopters. In some instances, fixed wing attack aircraft were also added to the package.

FAC:
Forward Air Controller – usually a pilot assigned to a ground unit for air-to-ground liaison between aviation and ground units.

FLARE:
MK-45 – Parachute Flare
The aircraft-launched Mk 45 Mod 0 aircraft parachute flare is used for night illumination of surface areas in search-and-attack operations. It replaces the Mk 24 Mods aircraft parachute flare.
The Mk 45 Mod 0 aircraft parachute flare is as an AUR, complete with the candle, parachute assembly, and fuse. All components are encased in a cylindrical aluminum body approximately 36 inches long (including the fuse assembly) and 4.9 inches in diameter.

The Mk 364 Mod 0 fuse is shipped installed in the flare. Its sole purpose is to control the altitude of flare ejection in relation to launch altitude. It does not directly control candle ignition. The fuse has 15 functional settings and 1 SAFE setting. The functional settings are at 1,000-foot intervals from 1,000 to 14,000 feet, except that 1 minimum setting of 500 feet is provided. The fuse-setting mechanism consists of a single yellow dial indicator you can easily turn by hand-clockwise for setting and counterclockwise for safing. A spring-loaded detent holds the dial indicator at a selected setting or at SAFE, and prevents accidental changing of the setting by vibration forces.
FREE FIRE ZONE:
A battle area or combat zone in which no restrictions are placed on the use of arms or explosives.

GUARD Channel:
The universal radio channel monitored by all aircraft on which emergency transmissions and requests for assistance are made.

GUNSHIP:
A huey or cobra helicopter, with mounted guns, rocket pods or other weapon systems, used to provide air to ground support for escort of other helicopters or Close Air Support (air to ground gunnery) for troops on ground.

H&MS:
Headquarters and Maintenance Squadron, a unit of a Marine Aircraft Group that performs both administrative functions and intermediate level aircraft maintenance. In some cases, an H&MS would operate small numbers of specialized aircraft, such as the CH-37C from 1965-1967.

HARDHAT:
An acronym for the aircrew member’s protective helmet.

Hill 55:
(and others such as Hill 845 etc) A means of identifying hill formations on the metric maps used in Viet Nam. The numbers indicating the height above sea level in meters of the highest point of that particular formation.

HMH:
Marine Heavy Helicopter Squadron, the first H means helicopter; the M means Marine; the second H means heavy.

HML:
Marine Light Helicopter Squadron, the first H means helicopter; the M means Marine; the L means light.

HMM:
Marine Medium Helicopter Squadron, the first H means helicopter; the M means Marine; the M means medium. (NOTE) The three numbers following these letters usually identified the original parent Marine Aircraft Group and the sequence in which the squadron was first commissioned. HMM-161 was the first squadron commissioned in MAG-16. HML-367 was the seventh squadron commissioned in MAG-36. There were exceptions. HMH-463 was not the third squadron commissioned in MAG-46. MAG-46 did not exist in the active force structure. it was then and still is a Marine Reserve Aircraft Group. As a wartime expedient both HMH-462 and HMH-463 were commissioned in other aircraft groups and, when operational, were transferred to MAG-36 and MAG-16 respectively.

I CORPS:
Viet Nam was divided into 4 geographical areas known as Corps in order to delineate responsibility for the military operations therein. From north to south they were I Corps, II Corps, III Corps and IV Corps. Early in the war, The US Marines were designated responsible for I Corps, which extended from the DMZ in the north and included the provinces of Quang Tri, Thua Thien, Quang Nam, Quang Tin and Quang Ngai Province in the south.

IFR:
Instrument Flight Rules, a condition during which a pilot is flying in the clouds on instruments, and without reference to either the natural horizon or the ground.

KIA:
Killed In Action.

LPD:
Landing Platform Dock, a Navy amphibious ship, capable of supporting and operating a small number of helicopters for an extended period of time. Usually, 4 to 6 on board with 2 being operated simultaneously.

LPH:
Landing Platform Helicopter, a Navy amphibious ship, capable of supporting and operating a squadron of helicopters for an extended period of time, and capable of transporting and off-loading a battalion of Marines at the same time.

LZ:
Landing Zone, an unimproved site where helicopters landed in the performance of their assigned mission.

M-60:
The standard light machine gun of US Marines in Viet Nam, in both ground and aviation units. In helicopter squadrons, M-60s were mounted in fixed forward firing positions on UH-lE gunships, and on flexible pintle mounts in the UH-1E side doors as well. They were also employed in the door or windows of transport helicopters (UH-34, CH-46, CH-53).

MAB:
Marine Amphibious Brigade, a temporary headquarters superimposed over such amphibious units as a Regimental Landing Team and a Provisional Marine Aircraft Group. The MAB was identical in mission and structure to the Marine Expeditionary Brigade (MEB.)

MABS:
Marine Airbase Squadron, the housekeeping unit of a MAG.

MACV:
Military Assistance Command Viet Nam, the senior US headquarter charged with overall responsibility for conduct of the war.

MAG:
Marine Aircraft Group, the unit immediately superior to aircraft squadrons, A helicopter MAG typically would have the following squadrons:
3 HMMs, I HML, I HMH, 1 H&MS, and I MABS attached.

MEB:
Marine Expeditionary Brigade, identical to the MAB discussed above.

MEDEVAC:
Medical evacuation, the term generally used to identify the mission of Marine helicopters involved in rescuing wounded, injured, and sick personnel.

MMAF:
Marble Mountain Air Facility, the home of MAG-16 from August, 1965 until May, 1971, located east of the Da Nang Air Base, on the beach, between China Beach and the Marble Mountains.

MOS:
Military Occupational Specialty – four digit code for a specific job type.

MSO:
A US Navy wood-hulled mine sweeper.

MUV:
Marine Unit Vietnam, the temporary identification of Marine helicopter squadrons operating from Da Nang Air Base in 1965 prior to the arrival in country of MAG-16.

NSA:
Naval Support Activity, a US Navy organization responsible for various support functions in the Da Nang area, such as port facilities, fuel storage areas, and hospitals, i.e., the NSA Hospital.

NVA:
North Vietnamese Army.

NW:
Northwest

0-1, 0-IC:
A light single engine observation aircraft used for forward air control, artillery spotting and general reconnaissance, from 1962 to 1969.

OV-IOA:
A twin turboprop, twin boom observation aircraft that replaced the 0-1s in 1968. It had significantly greater performance and carried a larger payload.

POW:
Prisoner of War.

PROVMAG:
Provisional Marine Aircraft Group, a temporary group organized for a limited period of time to meet a specific tactical or operational need.

QEC:
Quick Engine Change, an expedient procedure developed to quickly change the engine of a downed helicopter in the field.

RLT:
Regimental Landing Team, a US Marine infantry regiment specifically task organized and equipped to conduct amphibious or helicopter-borne landings from the sea.

ROCKET:
2.75″ HE Rocket – high explosive
2.75″ WP Rocket – white phosphorus (Willie Peter)
The LAU-59 rocket pod held seven 2.75″ FFARs. LAU means Launcher Aircraft Unit. FFAR means Folding Fin Aircraft Rocket. The rockets could have different types of warheads. HE (high explosive) rockets were used against targets made of wood or truck type steel. HEAT (high explosive anti-tank) heads had a shape charge and were used against armored vehicles. WP (white phosphorus) heads were used to either mark a target with smoke or as an incendiary weapon. The LAU-59 pod was reusable and was returned with the aircraft for reloading. The LAU-68 was a newer version of this pod. The LAU-3 was a 19 tube rocket launcher.

 

RPG:
Rocket Propelled Grenade, an enemy grenade fired from a device utilizing a small rocket propellant charge, greatly increasing its normal range.

RVN:
Republic of Viet Nam.

SAR:
Search and Rescue, the mission assigned to either dedicated aviation units or other available aviation units related to locating and extracting downed aircrews and other personnel. The term CSAR identified Combat Search and Rescue units of the Air Force and Navy who were specifically trained and equipped to operate in heavily defended North Vietnamese airspace to conduct SAR missions.

SAR NORTH:
The SAR mission north of the DMZ assigned in the early years of the war to Marine HMM squadrons, prior to the assignment of the specific CSAR units discussed above.

SHU-FLY:
The name coined for the initial introduction of USMC helicopters into Viet Nam in 1962.

SLF:
Special Landing Force, the designation of the USMC BLT and HMM squadron assigned to the Seventh Fleet Amphibious Ready Group. The SLF regularly conducted amphibious operations across Vietnamese beaches into areas of suspected VC and NVA activity.

SLICK:
A huey helicopter with no mounted guns, generally used for recon team insertion, TAC(A), VIP transport, and medevac.

SW:
Southwest.

TAC(A):
Tactical Air Controller (Airborne) – either a qualified pilot or a qualified Aerial Observer who is responsible for the safe conduct of air-to-ground strikes, artillery strikes or naval gunfire missions.

TAOR:
Tactical Area of Responsibility, the geographical area assigned to a military unit having responsibility for all operations therein, i.e., the First Marine Division’s TAOR was the city of Da Nang and surrounding areas defined by specific features such as rivers, roads etc.

TF:
Task Force, a unit temporarily organized to carry out a specific short term mission.

UH-1, UH-IB, UH-1D:
The “Huey” was the standard small troop carrying helicopter in Viet Nam, primarily used by the Army.

UH-1E:
The Marine version of the huey, the UH-1E was designed for the USMC to operate from shipboard. Primary differences included a rotor brake, an alternating current electrical system, aluminum construction for shipboard use and air to ground and air to air radios. The mission of the Marine huey was command and control, liaison, observation, gunship, and medevac missions.

UH-34D:
The standard USMC medium helicopter at the beginning of the war. It served in Viet Nam from April, 1962 until August, 1969.

UA:
Unauthorized Absence, both a disciplinary term, and an acronym for anything or person not in the place it is expected to be.

UTT:
Utility Tactical Transport, the name of the Army’s UH-1B gunship unit early in the war when the helicopter gunship was still in an experimental state.

VC:
Viet Cong, or Charley, the original enemy in South Viet Nam.

VMO:
Marine Observation Squadron, the V means fixed wing; the M means Marine; the 0 means observation.

VNAF:
Vietnamese Air Force.

WIA:
Wounded in Action.

XO:
Executive Officer, the second in command of a unit.

ZERO/ZERO:
Zero ceiling, zero forward visibility, as in IFR flight conditions.