Who Goes There: Friend or Foe?

June 1993

OTA-ISC-537

NTIS order #PB93-218915

GPO stock #052-003-01328-2
Recommended Citation:

U.S. Congress, Office of lkchnology Assessment, Who Goes There: Friend or Foe?,

OTA-ISC-537 (Washington, DC: U.S. Government Printing Office, June 1993).
T

Foreword

he recent Persian Gulf War focused attention on the problem of fratricide, or

“friendly fire” casualties among combat units. Twenty-four percent of U.S.

combat fatalities in that conflict were due to friendly fire. The House Armed

Services Committee requested that OTA assess the technology and techniques

available to reduce this tragic loss of life. Although friendly fire has often been dismissed

in the military literature as an insignificant contributor to overall combat losses, in those

few historical cases for which good data are available, estimated friendly fire losses have

accounted for at least 10 percent of total losses. Friendly fire has been an important-and

under-appreciated-source of combat deaths.

Combat is confusing, complex, and deadly. Friendly fire casualties can probably

never be eliminated, but several measures can reduce them. Application of new and existing

technology can make identification of friendly forces on the battlefield more reliable;

improved communication can reduce confusion on the battlefield; and better training can

help military personnel make crucial, rapid decisions under the extreme stress of combat.

Congress faces several decisions related to reducing friendly fire. These include:

the choice of best technical approaches to pursue;

the allocation of resources between systems that are devoted exclusively to

reducing friendly fire and other systems—for example, better navigation and

communication devices--that may reduce friendly fire in indirect and less

visible ways;

the best mix of near-term deployments and longer term research and

development; and

the need for cooperation and coordination among the military Services and with

allies.

We wish to express our appreciation to individuals in the many government agencies

and other organizations that provided information essential to the assessment and to the

many reviewers who helped ensure its accuracy.

Roger C. Herdman, Director

lit
Preject Staff

IVAN OELRICH

Project Director

Peter Blair

Assistant Director, OTA

Energy, Materials, and International

Security

Lionel S. Johns

Assistant Director, OTA

(through May 5, 1993)

Energy, Materials, and International

Security

Alan Shaw

International Security and

Commerce Program Manager

ADMINISTRATIVE STAFF

Jacqueline Robinson Boykin

Office Administrator

Louise Staley

Administrative Secretary

Madeline Gross

Contractor

CONTRACTORS

Elizabeth Sheley

Editor

Richard R. Muller

Air University

Air Command and

Staff College

John C. Lonnquest

Department of History

Duke University

iv
1

2

3

Introduction, Findings, Issues

for Congress 1

Findings 2

Issues for Congress 5

Historical Review of the Causes of

Fratricide 7

Types of Fratricide 9

Tactical Constraints Due to Fear of Fratricide 1 8

The Prevalence of Fratricide 20

The National Training Center 2 4

Fratricides During the Persian Gulf War 2 6

Summary 2 8

Avoiding Fratricide:

General Considerations 29

Trends in the Frequency of Fratricide 3 0

Measures of the Severity of the Problem 3 1

The Attack Sequence 3 2

The Combatant’s Sources of Identification

Information 3 3

Identification: Friend or Foe 3 8

Making Choices About How To Avoid Fratricide 45

Conclusion 4 8

(Continued on next page)

contents

--

v
4 Avoiding Fratricide of Air and

Sea Targets 49

Battle Management 49

Noncooperative IFF 50

Cooperative Question-and-Answer IFF Systems 56

Coordination With Civilian Air Traffic Control 62

Identification of Ships 66

A Comprehensive Identification System 67

5 Avoiding Fratricide of Land Surface

Targets 69

Increasing Knowledge of the Tactical

Environment 70

Identification Systems 72

Dismounted Infantry 76

Noncooperative Identification 77

Current Programs 78

Tactics, Doctrine, and Training 79

Conclusions 7 9

INDEX 81
— —

Introduction,

Findings,

Issues for

Congress 1

A

merica’s recent combat in the Persian Gulf War brought

new attention to an old problem: fratricide, or ‘‘fi-iendly

fire, ’ that is, casualties from U.S. or allied weapons fired

at U.S. or allied military personnel. Twenty-four percent

of all U.S. combat fatalities in the war were caused by friendly

fire. This figure seemed much higher than in previous wars and

caused a sudden focus on avoiding fratricide in future wars.

The U.S. military and the American public are becoming

increasingly sensitive to the human costs of military involvement, especially for contests of less than national survival. The

United States has invested much in energy and equipment to keep

casualties low. The high fraction of deaths in the Persian Gulf

War due to fratricide was much higher than the nominal two

percent rate frequently cited in the military literature. Broadbased data on fratricide rates are not available; but, a recent

review of long-extant casualty surveys from World War II and

the Vietnam War shows that fratricide estimates of 2 percent are

unrealistic and 15 to 20 percent may be the norm, not the

exception. Thus, one reason that fratricide seemed unusually

high in the Persian Gulf War is that total U.S. casualties were low

but another important reason is that past rates of fratricide have

been systematically and substantially underestimated. If these

rates are, indeed, typical, then reducing casualties from fratricide

deserves the same kind of attention as reducing casualties from

any other major source.

Beyond numbers of killed and wounded, fratricide has a

compounding effect on combat effectiveness. Weapons aimed at

friends are not aimed at the enemy. Friends killed by friends are

not able to fight the enemy. Moreover, the psychological effects

of friendly fire are always greater than from similar enemy fire.

Combatants expect to be shot at by the enemy, but being shot at

1
2 I Who Goes There: Friend or Foe?

Table l-l—Detrimental Effects of Fratricide

●

●

●

●

●

●

●

●

●

●

Hesitation to conduct limited visibility operations

Loss of confidence in unit’s leadership

Increase of leader self-doubt

Hesitation to use supporting combat systems

Oversupervision of units

Loss of initiative

Loss of aggressiveness during fire and maneuver

Disrupted operations

Needless loss of combat power

General degradation of cohesion and morale

SOURCE: Center for Army Lessons Learned.

by friends corrodes cooperation and morale;

shooting at friends also destroys morale and can

cause commanders to be overly cautious in

combat. See table 1-1.

The Persian Gulf experience has concentrated

the attention of the military Services on the

problems of fratricide. Several new antifratricide

programs were started within the Department of

Defense, and existing programs have been accelerated, reoriented, or brought under new management control. New emphasis has been given to the

fratricidal implications of other programs-such

as those to improve communication-not explicitly or primarily intended to reduce fratricide.

Doctrine and training are also being reexamined

with a view to minimizing the risk of fratricide.

FINDINGS

Fratricide may be a significant source of

casualties. Twenty-four percent of U.S. combat

fatalities in the Persian Gulf War were caused by

friendly fire. This seemed extraordinarily high

compared to past conflicts. Several reasons have

been

been

1.

2.

presented for why the fraction should have

so large:

total U.S. losses were very low, thus the

percentage of fratricides appeared abnormally high;

the war was so short that U.S. troops did not

have a chance to gain much experience,

reduce fratricide, and get the average down;

3.

4.

near-absolute dominance of the battlefield

by the U.S. meant that only U.S. rounds

were flying through the air and if a soldier

got hit by anything, it was likely to be from

a U.S. weapon; and

the unique characteristics of many U.S.

weapons, for example, the depleted uranium in the M-1 tank round, made the

fratricide that did occur undeniable.

Some of these reasons will apply to a range of

possible future military engagements. Whether or

not fratricide in the Persian Gulf was particularly

high compared to past wars, it may be representative of future conflicts.

The fourth point above deserves careful consideration. While military historians have frequently used two percent as a notional fratricide

rate, the figure has been higher in all of those

cases for which good data are available. A recent

review of medical records from World War II, the

Korean War, and the Vietnam War show fratricides to account for 12 percent and more of total

casualties in those cases for which data are

available. Perhaps the Persian Gulf War was not

so unusual.

Reducing fratricide is desirable and feasible, but eliminating it is not. Although programs

to reduce fratricide are certainly needed, setting a

goal of eliminating fratricide is unrealistic and

probably even counterproductive. Overly restrictive rules of engagement, for example, may so

reduce combat effectiveness that casualties inflicted by the enemy increase more than friendly

fire losses are reduced. See figure 1-1.

The new global military environment requires a reevaluation of antifratricide efforts.

Any technical goals established during the days

of the Cold War need to be reexamined. Past

directions will not be completely reversed, but

priorities among technical direction may change.

For example, during the NATO-Warsaw Pact

confrontation, which type of weapon was on

which side was clear-cut. Today, noncooperative

identification based on type of weapon or plat-
Chapter I-Introduction, Findings, Issues for Congress 3

Figure l-l—Total Casualties and

Antifratricide Measures

[

—— —————

,

)

.

/

\ //

/

A

,< Total losses

‘ \ \

~..——–— I

\

Increasing losses /

\

\ from enemy fire > / ’

\

/’

‘,<

Declining losses /

from fratricide

\

/

\ /

‘ \

/ “

.

/

‘A/

z A

/

c1 ——— ’

r

-- -— ---

-——.-.—.

No antifratricide Too stringent antimeasure fratricide measures

>

More stringent antifratricide measures

SOURCE: Office of Technology Assessment, 1993.

form will be more difficult in a world in which

enemies and allies may own the same hardware.

Also, future alliances, like that in the Persian

Gulf, may be more ad hoc, making plannin g for

and sharing of identification technology more

difficult. On the other hand, some tasks should be

easier to accomplish since few potential enemies

will be as sophisticated as the former Soviet

Union or possess the sheer numbers.

Fratricide results from multiple causes. Friendly

fire is often thought of as due primarily, or

exclusively, to misidentification. Investigation of

particular cases usually reveals that the fratricide

was in fact the last link in a chain of mistakes.

That is, faulty navigation; poor communication,

command, and planning; lack of fire discipline;

and occasional malfunctioning equipment are

responsible at least as often as misidentification.

See figure 1-2.

With multiple links in a chain of causes, there

are multiple solutions to the problem of fratricide

by strengthening any of the links. For example,

outfitting tanks with compasses will improve

navigation, helping units to be where they are

supposed to be and not to stray into fields of

friendly fire. Improved radios allow the transmission of more of this navigation information.

Improved displays within the tank would allow

clearer representation of that information. And, of

course, better sensors would allow better recognition of fiends seen through the sights of the gun.

Each of these measures could reduce fratricide.

Some approaches to reducing fratricide have

other benefits. For example, improved communication and navigation allow better command and

control of combat units, more flexible tactics, and

more efficient allocation of combat resources. All

of this together could improve combat capability

significantly while also reducing fratricide. An

improved identification device will mostly reduce fratricide with much smaller side benefits.

Thus, only the appropriate fractions of the costs of

systems should be compared when considering

their relative efficiency in reducing fratricide.

Figure 1-2—Causes of Fratricide: Direct Fire

Fratricide in World War II, Korea, and Vietnam

Inexperience

190!0

/--\ Unknown factors

Target 1 00/0

m(sldentlflcahon

260/o

b“

% =

SOURCE: U.S. Army

Coordination

45%

Incidents by category

58 total incidents
4 I Who Goes There: Friend or Foe?

Wreckage of a U.S. armored vehicle destroyed by

friendly fire in the Persian Gulf War. The effectiveness

of modern weapons makes identification mistakes

deadly.

No single technical approach to target identification will be perfect. Identification techniques

can be roughly divided between cooperative and

noncooperative approaches. In general, cooperative techniques can provide positive identification of friends. Failure to respond to a cooperative

identification query could be assumed to identify

a putative target as an enemy, but in most

circumstances, most shooters would be hesitant to

use the lack of response as a justification to fire.

Cooperative techniques could, however, categorize targets as either friends or unknowns and then

noncooperative techniques could identify the foes

among the unknowns.

The technology for avoiding fratricide of

land surface targets lags behind the technology

important to avoiding aircraft fratricide. Avoiding fratricide requires good navigation, communication, and identification. Yet multimillion-dollar

U.S. tanks do not have compasses. Simple magnetic compasses will not work inside a 60-ton

steel box and tanks are only now being fitted with

radio-navigation equipment. Question-andanswer IFF systems, developed for aircraft a half

century ago in World War II, are only now being

developed for land combat vehicles. Programs to

reduce ground combat fratricide will need special

support for several years just to get up to where

aircraft systems are today.

Coordination among the U.S. military Services and among U.S. allies is essential. Programs

to develop technology to reduce fratricide must be

coordinated among Services and allies from the

beginnin g. The U.S. military emphasizes “combined arms” operations where the strengths of

many different types of weapons are brought to

bear simultaneously against an enemy. This

approach presents many opportunities for friendly

fire among aircraft, artillery, land vehicles, surfaceto-air missiles, and so on. Fratricide reduction, as

much as any other DoD effort, needs some central

coordination, either from Office of the Secretary,

the Joint Chiefs of Staff, or other special jointService organization. The Services realize the

importance of coordination, and their ongoing

multi-Service efforts should be encouraged and

monitored.

Future conflicts are likely to be allied operations—as much for political as military reasons—

and coordination of antifratricide technology

development with allies must be maintained from

the beginning. The utility in allied operations is

one criterion by which prospective technology

must be judged. For example, if technology being

pursued for identification of friend and foe is so

sensitive that it cannot be released to allies,

especially ad hoc allies as we had in the Persian

Gulf War, then the usefulness of the technology

will be limited. This does not mean that these

approaches are worthless, but the need for allied

cooperation should be included as a program goal.

Nonmaterial changes will also reduce fratricide. Some cases of friendly fire in the Persian

Gulf War could have been avoided by different

pre-war training. For example, since the war the

Army intentionally includes occasional stray

friendly vehicles in training exercises and maneuvers to let soldiers practice ‘ ‘don’t shoot’ situations. Simulators are an increasingly important

part of training. In the past, these have not fully

reproduced opportunities for fratricide; this lack

is now being addressed.
Chapter I–Introduction, Findings, Issues for Congress 5

The rules of engagement strongly affect the

likelihood of fratricide. The Services train warriors and train them to be aggressive, But in many

potential future conflicts, the conditions of the

Persian Gulf War may recur: the U.S. was able to

outrange, outsee, and outgun the enemy by a

substantial margin. This capability could allow

(but not demand) different rules of engagement.

Many Persian Gulf fratricide occurred when a

target was engaged quickly yet the shooter was in

no imminent danger and could have been more

deliberate. In situations where U.S. forces have

clear weapons performance superiority, more

conservative rules of engagement may reduce

overall U.S. casualties. This is a very complex

issue that is without a simple answer (e.g., if the

United States had fought more slowly battle-bybattle, perhaps the overall envelopment of Iraqi

forces would have failed), however, it at least

deserves consideration.

ISSUES FOR CONGRESS

I Allocation of Resources

Reducing fratricide will require new technology and equipment. That, in turn, requires funding, which then requires allocations within a finite

defense budget. There is, as always, competition

between efforts to reduce fratricide and other

military needs. Having combat superiority helps

to keep casualties down, so even if minimizing

casualties is the goal, spending less on offensive

weapons and more on avoiding fratricide is not

automatically the answer. Two issues, however,

suggest that the relative emphasis on fratricide

prevention should increase: first, most military

analysts interviewed by OTA for this assessment

agree that antifratricide efforts, especially related

to land combat, have not received sufficient

attention in the recent past. Second, the experience of the Persian Gulf suggests that fratricide

may be a relatively greater cause of casualties in

future conflicts than has been appreciated in the

past.

Each of the Services has IFF and antifratricide

programs, and Congress will be asked to allocate

resources among these. One of the findings of this

report is that technology to help prevent fratricide

of land surface targets is least developed and

Congress may consider giving relatively greater

weight for a few years to programs supporting

these technologies.

Resources must also be allocated among various technical approaches to reducing fratricide.

When comparing these costs, Congress may want

to consider the potential multiple benefits of

many approaches. Specifically, an IFF system

will reduce fratricide by improving identification,

but has only limited additional applications,

while improvements in communication and navigation can reduce fratricide and have compounding benefits to overall combat effectiveness.

1 Short-Term v. Long-Term Goals

After the Persian Gulf friendly fire losses, the

Services decided—with some prompting from

Congress-that an accelerated antifratricide program was needed. The Army developed a plan for

both “near-term” (less than 5 years) and “farterm" (7 or more years) solutions. The general

technical approach for the near-term solution is

fairly well determined to be a millimeter wave

question-and-answer system. This has the advantage of being available to troops in the field within

just a few years, although it is not the ideal

long-term solution. The degree of pressure from

Congress is part of the calculus by which the

Services determine their allocation of effort

between near- and long-term solutions. Congress

may wish to make clear to the Army the extent of

its urgency:

●

●

should the Army get a less-than-ideal system

in the field quickly so soldiers have something in the event of a new Persian Gulf-like

conflict, or

should the Army take a longer-term approach to get a better system while risking
6 I Who Goes There: Friend or Foe?

that a conflict within 5 years or so may result

in too many friendly fire losses?

M Cross-Service Coordination

There is probably no better example of an effort

where inter-Service coordination is needed than

the development of antifratricide technology and

equipment. The Services now have a General

Officers Steering Committee that seems quite

successful in assuring coordination among various Service antifratricide programs. Congress

may want to pay special attention to Service

coordination in future years to ensure that it is

maintained at every level. Past experience is not

uniformly encouraging.

One technical aspect of Service coordination is

the compatibility of various IFF devices. Not

every weapon can effectively fire at every other

weapon; for example, fighter/interceptor aircraft

and tanks cannot fire at each other. Is it really

necessary that they be able to query each other’s

IFF devices? Yet fighters can fire at groundattack aircraft and ground attack aircraft can fire

at tanks. If they do not all have the same IFF

systems, will ground-attack aircraft need two

systems operating in parallel?
———

Review of the

Causes of

Fratricide 2

n November 12, 1758, during the French and Indian

War, Colonel George Washington of the British Army

led a detachment of infantry to take a hill near Loyall

Hannon (now Loyalhanna), Pennsylvania occupied by

French soldiers and their Indian scouts. The French fled after a

brief exchange of fire. But hearing the firing, a second detachment—under the command of Lt. Colonel George Mercer—

approached the hill to assist. They arrived at dusk and the day was

foggy, making visibility poor. Each side seems to have mistaken

the other for French and an intense fire fight broke out, killing

between 13 and 40.1

While the current high interest in combat fratricide is a direct

result of U.S. experience in the Persian Gulf War, this tale shows

clearly that fratricide is not a new problem. During the Persian Gulf

War, incidents of fratricide received considerable press attention

and caused international political friction.2 There was bewilderment among the public and press about how fratricide could occur.

After all, shouldn’t it be obvious who are friends and who are foes?

In addition, to some the losses from friendly fire seem less acceptable as an inevitable cost of war than are losses from enemy fire.3

1 The Papers of George Washingto~ Colonial Series, vol. 6, W.W. Abbo4 ed.

(Charlottesville, VA: University Press of Virgini% 1988), pp. 120-123. A “detachment”

could consist of between 200 and a thousand infantry.

2 Just a sample of the popular press stories about friendly fme includes: Bruce van

Voorst, “They Didn’t Have to Die, ” Time, Aug. 26, 1991, p. 20; Joshua Hammer,

“Risking Friendly Fire, ” Newsweek, Mar. 4, 1991, p. 33; David HackWorth, “Killed by

Their Comrades, ” Newsweek, Nov. 18, 1991, pp. 45-46; Glem Frankel, “In Britain,

Fallout from Friendly Fire, ” Washington Post, May 18, 1992, p. Dl; and David MOrnSOrL

“Foes Not the Only Threat in the Gulf War,” Narional Journaf, Feb. 9, 1991, pp. 335-336.

3 Sensitive to the possibility of a different reaction to friendly fire losses, the Marine

Corps readily admitted occurrences of friendly fwe but was reluctant to identi& precisely

which deaths it caused. For example, a Marine Corps spokesman, Lt. Col. Ron Stokes,

was reported as saying: “We don’t want to start painting guys with a different

brush-these guys were killed by the enemy and these guys by friendly fire. They were

all killed in a combat action. If you start breaking it down, we’re not certain that it benefits

either the public or the families. See, ‘‘Kitled by Friend or Foe, It’s All the Same, ” The

New York Times, Feb. 14, 1991, p. B18.

7
8 I Who Goes There: Friend or Foe?

The fratricide of the Persian Gulf War was

unusual in some regards compared to that of past

wars. Most striking was the apparently unprecedented high fraction of U.S. casualties resulting

from fratricide; this was due in large part, of

course, to the extremely low U.S. casualties

inflicted by the enemy.

In addition, the types of fratricide were different from other large mechanized land battles, such

as those of World War II. In World War II, the

most deadly reported individual incidents of

fratricide were the result of bombing of friendly

troops by friendly aircraft. Surface-to-surface

fratricide resulted most often from indirect-fire

weapons, that is, artillery fired at a target that the

crews could not see. The Persian Gulf War had an

unusually high fraction of fratricides from directfire weapons—for example, tanks-shooting mistakenly at other land targets, which they could see

but misidentified.

This chapter, a historical review of fratricide,

shows how serious a problem fratricide has been

in past wars and reveals patterns in the occurrence

of fratricide in past wars that might suggest

lessons for the future.

There are difficulties with a historical approach. The movements of armies are usually

well recorded, but the record of particular actions

by front line soldiers that might lead to fratricide

is spottier and less reliable. Thus, many casualties

due to fratricide are never realized to be such, and

many that are recognized as fratricide are probably never recorded as such. Within the military

historical record, the record of fratricide is particularly suspect because fratricide is a mistake and

a full airing can be embarrassing or traumatic and

can end careers.

Recording of fratricide has not been uniform.

Casualty report forms, for example, have not

included fratricide as a cause. Thus, fratricides

during the Vietnam War were cataloged under

either ‘‘accidental self-destruction” or “misadventure.

Colonel Washington’s unfortunate “misadventure” illustrates these problems well. After

the Loyalhanna incident, Washington was criticized by some of his officers for losing his

customary aplomb under fire, for which he was

justly famous. What responsibility he felt after the

action we can never know, but he made no

mention of the circumstance of his casualties in

the next day’s reports to his superior officers. In

fact, he never mentioned the event in any of his

writings until almost 30 years later when, in

marginal comments on a draft of his own biography, he related a version in which Colonel Mercer

clearly fires the first shot.

The historical record does provide lessons.

Many of the cases of fratricide include human

errors, not just technical or tactical specifics.

Because people change more slowly than machines, history probably provides some useful

lessons for today.

Very few works are devoted specifically to

fratricide. One particular case of fratricide is

probably the most famous because a popular book

was written about it, Friendly Fire, by C.D.B.

Bryan (also serialized in the New Yorker and the

subject of a television series);4 this work deals

primarily with a victim’s family and its dealings

with the U.S. Government. Lt. Colonel Charles

Schrader’s paper, Amicicide, contains far and

away the largest collection of historical ancedotes

of fratricide of any single source and it is cited

widely in this chapter.5 OTA also contracted for

two papers on fratricide and they are used freely

in this chapter.6

4 Courtlandt Dixon Barnes Bryan, Friendly Fire (New Yorkj NY: Putna.q 1976).

5 Charles Schrader, Amicicide: The Problem of Friendly Fire in Modern War (Fort Leavenwo!@ KS: U.S. Army Comman d and General

Staff College, 1982).

c Richard R. Muller, “Fratricide and Aerial Warfare: An Historical Overview” and John C. Imnnquest and W. Blair Hayworth, Jr., ‘‘OTA

Fratricide Study.”
—. — .—

Chapter 2–Historical Review of the Causes of Fratricide 9

This chapter is organized not by chronology

but rather by the lessons important to finding

technical and procedural solutions to the problem

of fratricide. This approach is necessarily somewhat arbitrary since fratricide almost always

results from a complex and confused chain of

mistakes, making strict categorization impossible. (A gunner may aim toward a friendly target

because he is disoriented but certainly will not

pull the trigger unless he also fails to identify the

target properly. Is the fratricide then due to his

disorientation or his failure in identification?)

The chapter concentrates on, but does not

restrict itself to, American experience. This

should not, of course, imply that the U.S. military

has a particularly serious problem with fratricide;

even a quick glance at military history shows that

every army that has fired a shot has had to take

into consideration hitting one of their own, or else

quickly learn hard lessons. Following the historical anecdotes are some data from the National

Training Center—an instrumented, automated

facility for combat manuevers--and finally a

synopsis of the Persian Gulf incidents.

TYPES OF FRATRICIDE

There are no universally accepted definitions

of friendly fire’ or ‘‘fratricide. The broadest—

and older-definitions include any case in which

anyone is hurt by a weapon from his own side

other than his own. Thus, if an artillery round is

faulty and falls short on friendly forces, that is

friendly free; but if it is faulty and blows up in the

breech and kills the artilleryman pulling the

lanyard, that is an accident. More recently, the

military has adopted definitions that exclude pure

accidents and grossly malfunctioning equipment.

The narrowest definition would include only

willful, but mistaken, attacks on friendly forces.

The current Army Training and Doctrine Command (TRADOC) definition is: ‘‘The act of firing

on friendly personnel or equipment, believing

that you are engaging the enemy. ’

This report uses a definition that excludes

purely mechanical malfunctions but includes all

other cases of friendly personnel receiving fire

from weapons operated by other friendly personnel. Perhaps surprisingly, the material difference

between the definitions is not great since few

fratricide result solely from equipment failure.

1 Fratricides Due to Accidents

Malfunctions always occur, of course, and

when dealing with weapons, they can be deadly.

For example, in 1968, an F-4 flying to support

troops engaged near Ban Me Thout, Vietnam,

dropped a napalm canister on a church, killing 13

civilians. The cause was determined to be simply

a faulty bomb rack.8

More often, however, malfunctions are just

part of a chain of errors, sometimes compounded

by human actions. For example, in World War 11,

the lead bomber of a group would determine the

target and all others in the group would release

upon seeing the leader’s release. During the attack

on the Abbey of Monte Cassino in March 1944,

a bomb rack malfunction resulted in the premature release by a lead bomber, which resulted in

its and others’ bombs being dropped on friendly

positions. Similarly, on July 24 of that year,

during the preparation for the breakout toward St.

Lo, when the bomb rack on one lead bomber

prematurely released, the other 15 bombers in the

group immediately released their loads; unfortu7 Briefing entitled, “TRADOC Fratricide Study” (undated but received 1992). Note that, in practice, the Army does not always stick with

this very strict definition, For example, some of the incidents from the Persian Gulf would have to be called “accidents” if using this wow

definition,

8 Schrader, op. cit., footnote 5, p. 55.
. . . . . . .— ---- -- . -. --- . . - . . . - - - -

10 I Who Goes There: Friend or Foe?

nately they landed on the U.S. 30th Infantry

Division, killing 25 and wounding 131.9

Ever since World War I, cases of rear gunners

damaging their own aircraft have been common

and continue to the present. Helicopter gunships

are equipped with traverse-limiting rods that

prevent the side-door machine-guns from swinging so far to either side that rounds could hit the

helicopter. When such a rod broke on one

helicopter during the Vietnam War, the gunner in

the heat of battle tracked a target so far forward

that he fired into the cockpit and wounded the

pilot.

Even when weapons operate properly, unfortunate circumstances can cause what, in the broadest sense at least, might be classed as fratricide

rather than accident. In the early morning hours of

5 November 1942 during the second Battle of

Guadalcanal, the destroyer Walke was hit by

Japanese naval guns and torpedoes. With the

burning destroyer clearly sinking just a few

minutes after being hit, the battleship Washington

passed close by and launched life rafts for the

Walke’s crew. However, when the destroyer went

down soon after, the depth charges on its hull

exploded—just as they were designed to when

reaching a certain depth-killing many of the

crew in the water above.10

Some accidents due to human error could be

avoided by different equipment design. A U.S.

bomber in World War H bombed an air base of the

U.S. Ninth Tactical Air Force after the bomber

was hit accidentally by a packet of chaff; the

surprise caused the bombardier to hit mistakenly

the bomb release switch.11 During the Vietnam

War, an F-100 attacking a North Vietnamese

Army Headquarters instead dropped bombs over

a kilometer short on U.S. troops when the pilot hit

the bomb release while trying to adjust the

aircraft’s trim button.12

S Fratricide Due to Command and

Control Failures

Failure of command and control is a far more

common cause of fratricide than simple failure of

equipment. Command and control includes telling units where to be, having units know where

they are, and keeping units properly informed of

the locations of neighbors.

The nighttime Battle of Cape Esperance began

late on the night of October 11, 1942, with the

destroyer Duncan breaking away from her group

and charging off in total darkness toward a

formidable Japanese fleet. The Duncan closed on

a Japanese cruiser and opened fire. The crews of

the American cruisers, seeing gun flashes very

near known Japanese cruisers, assumed that the

flashes came from a Japanese ship and attacked

with eight inch guns. The flashes stopped almost

immediately. Very likely the target had been the

hapless Duncan, which was in flames, unable to

free, and sinking within ten minutes of leaving its

group. (Misidentification had been her downfall

but it might also have saved her from further

attack. During the Japanese retreat, the Japanese

apparently also assumed that the ship within their

midst was Japanese and did not attack, although

heavy cruisers passing very close by could have

disintegrated the little destroyer with a single

salvo.13)

9 Robert H. George, ‘‘The Battle of France,” in The Army Air Forces in World War II, Volume Three, Europe: Argument to V-E Day,

January 1944 to May 1945, Wesley Frank Craven and James ha Cate, eds. (Washington, DC: U.S. Government Printing OffIce, 1983), pp.

228-277.

10 ~5 repated a s~w ~agedy of a week ~lier when the des~oyer ~fey S* ~d her &p~ chmges killed several C)f those few (Xew

members that were able to abandon ship. C.W. Kilpatrick, The Naval Nigh Battles in the Solomons (Pompano Beack FL: Exposition Press

of ~Oli@ 1987), pp. 91, ] ] 8, and 121.

1 I by h Forces, op. cit., footnote 9, p. 230.

12 Sctiader, op. cit., foomote 5, p. 58.

13 Kflpa~&, op. cit., foomote 10, pp. 52-64.
.. — — .——..—

Chapter 2–Historical Review of the Causes of Fratricide! 11

The occasional misplaced shot is bad enough,

but worse fratricide can occur when two friendly

units start exchanging fire. One unit fires by

mistake and the other unit-assuming fire to be a

positive identification of enemy—returns fire. On

August 8, 1944 during the fighting on Guam, two

battalions of the 77th Infantry Division got into a

prolonged fire fight. The exchange might have

started as each side fried off several mortar rounds

to calibrate the weapons’ emplacement positions

before settling down for the night. Rounds from

each side fell near the other; both assumed that it

was Japanese fire and thus returned fire with

small arms and more mortars. This firing, of

course, made it obvious to each unit that the other

was enemy and then the accompanying tanks got

involved. A real firefight was under way. Finally,

their mistake became apparent, in part when each

battalion called up the same artillery battalion to

request that artillery fire be directed at the other.

A similar exchange became one of the worst

cases of fratricide in the Vietnam War. One

artillery unit aimed its guns correctly but used the

wrong powder charge so the rounds went too far

and landed on another U.S. artillery position. The

second position responded with deadly accurate

counterbattery fire. This duel went on for over 20

minutes and resulted in 90 casualties, all from

friendly fire.14

Command and control procedures can prevent

fratricide when identification is difficult. From

the time that aircraft were first used for ground

support in World War I, airmen knew that

identification of ground units would be difficult.

General William ‘‘Billy’ Mitchell said, “Our

pilots had to fly right down and almost shake

hands with the infantry on the ground to find out

where they were. ’15 To avoid fratricide, both of

infantry and pilots, World War I military comB-17s of Eighth Army Air Force bombing Berlin in

1944. One plane strays beneath another and has its tail

clipped by falling bombs. Even perfect identification of

friends will not eliminate all fratricide.

14 sc~ader, op. cit., footnote 5) P. 21.

15 Ric~rd Hallion ~frjjre From f~e Sk),,. The ~i$tov, ~}f Bar(/efie/dAir Ar~ack, ]9]]-1945 (Was~~on, DC: Smithsonian Institution pI13SS,

1989), p. 39.
---- . . . - ..-. — - -- -- - - - — --- - - - -

12 I Who Goes There: Friend or Foe?

manders divided up combat areas into ‘‘no-fwe”

zones and “free-fire" zones.16

At the outbreak of World War II, the Germans

had the best developed system for air-ground

coordination. They began with a World War I

system of colored panels to mark infantry positions. This worked well in the attacks on Poland

until Polish defenses broke and the German army

began a war of maneuver. The German 10th

Panzer Division then reported ‘constant” attacks

by friendly airplanes.17 The same story was .

repeated on the Western front, the Germans

introduced a system of safety lines (Sicherheitslinie) to avoid attacks on their own troops,18

which worked well at first but, again, once a war

of maneuver began deep in French territory,

fratricidal attacks increased sharply.

Clearly, in both cases above the change was not

in the ability to identify; German pilots did not

suddenly forget how to identify tanks that they

could have identified the day before. Rather,

identification had been difficult all along and

operational command and control procedures,

developed to serve in lieu of identification, broke

down when the character of the fighting changed.

Recognizing the importance of rapid maneuver, and the strain it placed on any operational

measures to avoid fratricide, the Germans worked

diligently to develop better ground-to-air signaling and training programs to increase pilots’

identification skills.

The single most famous case of fratricide

illustrates the extreme difficulty of coordinating

a complex attack by hundreds of elements, even

along a stationary front. The carpet bombing in

World War II classroom instruction in aircraft

identification using resin models.

preparation for the Normandy breakout near St.

Lo was filled with problems, with those precipitated by mechanical failure of a bomb rack cited

above being just the beginning.

German defenses around the Allied armies in

Normandy were tenacious but spread thin. Allied

commanders decided that a single, concentrated

blow would breach the defenses, allowing Allied

armor to pour through the gap. The plan to

puncture the defenses was called Operation COBRA.

The first phase of the breakout was to be a carpet

bombing of German positions. The attack was to

start with 380 medium bombers hitting specific

targets, followed by over 1,500 heavy bombers,

B-17s and B-24s, dropping over 3,300 tons of

bombs, with over 500 fighter-bombers and divebombers attacking anything that survived. For

three hours, the sky would be filled with airplanes. 19

16 M~~~ ~Wer, ~d,, The united StateSAi~S~~iC~ in world w~~], vo~, II (washingto~ Dc: Office of Air Force fistory, 1978), p. 373.

17 Williamson Murray, “The Luftwaffe Experience, 193941,‘‘ in B.F. Cooling, cd., Case Studies in the History of Close Air Support

(Washington DC: Office of Air Force History, 1990), pp. 85-86.

16 Ge.do. ~.~eekows$ Ia, ~age~eft Z. Km Nr 2, ‘‘Zusamrnenarbeit d der Luftwaffe, ’ National ArChiWS and Records

Administration Washington (NARA) T3 14/615/372-393.

19 ~ese nub~s come from Cmven ad Cate, op. cit., foo~ote 9, p. 232. Most of the narrative is taken from MilrhXl“ Blumensoq Breakout

and Pursuit (WashingtorL DC: Department of the Army, OffIce of the Chief of Military History, 1961), pp. 228-239. Part of the problem with

a historical review of fratricide can be seen by a comparison of these two “official” histories, one by the Air Force, the other by the Army.

The Army was on the receiving end and their history relates much of the controversy between the air and ground commands, while the Air Force

history states somewhat matter-of-factly that “Wchnically viewed, the bombing was good. ” (p. 233)
Chapter 2—Historical

The attack was delayed a week by weather,

Then the July 24, 1944 attack was partially

underway when it, too, was called off because of

low visibility. (But not before the inauspicious

short bombing described above.) Finally, the

main attack took place on July 25.

General Omar Bradley thought that the benefit

of the bombing would be greatest if the infantry

attack could follow immediately after. He wanted

ground forces as close as 800 yards even though

the air commanders warned that 3,000 yards was

the closest safe distance. They compromised at

1,450 yards.

Bradley and other ground commanders had

insisted that the bombers approach parallel to the

front, so that any ‘‘short’ bombing would result

in bombing the wrong Germans, not in bombing

the wrong side. The air commanders argued that

this made their machines too vulnerable to

antiaircraft fire. Bradley seems to have believed

that he had agreement when he left the last

planning meeting. Years later he insisted that

“the Air Force brass simply lied” about the

direction of the attack.20

With so many aircraft, mistakes were inevitable, Visibility was poor. Heavies were to bomb

from 15,000 feet but a layer of clouds forced

many down to 12,000 feet, which in turn forced

groups to reassemble in crowded skies and

bombardiers to recalculate bombing solutions in

flight. Allied positions were marked with smoke,

which was hard to see in the haze and essentially

useless once the bombing started, since the bomb

explosions raised mountains of dust that mixed

with the smoke.

Human error was the cause of most of the short

bombings. Mistakes were disastrous when committed by the lead plane of a group because

command and control procedures called for the

lead plane to sight the target and all other planes

to release when the leader did. One lead plane had

. .

Review of the Causes of Fratricide 13

a broken bomb sight and released visually.

Another bombardier thought he was on target but

was orienting on the wrong landmarks.

Succeeding flights of bombers would almost

never be able to see their targets because of the

dust raised by first salvos. Therefore, their attempts to bomb targets were really the bombing

of dust clouds, under which they hoped the bombs

would find targets on their own.

Unfortunately, in this case, wind blew the dust

toward U.S. positions and every wave of bombers

struck a little closer. The war correspondent Ernie

Pyle wrote later:

As we watched there crept into our consciousness a realization that windows of exploding

bombs were easing back towards us, flight by

flight, instead of gradually easing forward, as the

plan called for. Then we were horrified by the

suspicion that these machines, high in the sky and

completely detached from us, were aiming their

bombs at the smokeline on the ground, and a

gentle breeze was drifting the smokeline back

over us! An indescribable kind of panic comes

over you at such times. We stood tensed in muscle

Soldiers of the U.S. 30th Infantry Division dig out after

being bombed near St. Lo by the U.S. Eighth Army Air

Force.

20 l-l~lio~ op. cit., fOOtIIOte 15, p. *11.
14 I Who Goes There: Friend or Foe?

and frozen in intellect, watching each flight

approach and pass over us, feeling trapped and

completely helpless.21

A company commander wrote,

The dive bombers came in beautifully and

dropped their bombs right where they belonged.

Then the first group of heavies dropped them in

the draw several hundred yards in front of us. . .

The next wave came in closer, the next still closer.

The dust cloud was drifting back toward us. Then

they came right on top of us. We put on all the

orange smoke we had but I don’t think it did any

good, they could not have seen it through the

dust. ..22

The results of the misplaced bombing were

deadly. Added to the casualties of the abortive

attack on the 24th, the short bombings on July 25

caused official casualties of 490 wounded and

111 dead.23 In addition, the 30th Infantry Division

alone reported over 160 casualties due to “combat fatigue, ” that is, soldiers simply stunned by

the experience but not necessarily showing any

bodily damage.

Among the dead was Lieutenant General Leslie

McNair, Commanding General of the Army

Ground Forces, pro tern commander of the 1st

U.S. Army Group, and a strong supporter of

air-ground combined operations. He had come to

the forward area on the 25th specifically to help

morale after the short bombings of the 24th.24 He

was killed instantly and could be identified only

by his West Point ring.25

The bombings at St. Lo caused resentment

between air and ground commanders. The commander of the 30th Infantry Division said, ‘Theres

no excuse, simply no excuse at all. I wish I could

show some of those air boys, decorated with

everything a man can be decorated with, some of

our casualty clearing stations." 26 General Dwight

D. Eisenhower reportedly swore never to use

heavy bombers in combat support again, but their

usefulness was too apparent and the ban did not

last.

On the positive side, Operation COBRA also

motivated important U.S. improvements in command and control of bomber groups and in

procedures for marking of friendly lines on the

ground. During Operation QUEEN, the Allied

attempt to breach the Roer River, a carpet

bombing preparation like that for Operation

COBRA was to open the way for the infantry.

This time giant fluorescent cloth panels marked

the positions of friendly troops and tethered

balloons flew parallel to the front line. U.S. troops

also marked their positions by using their 90

millimeter antiaircraft cannon to fire red smoke

shells straight up, and the bombing went well.27

Repeating the earlier German experience, however, the Allies found that these command and

control procedures-depending on careful marking—

broke down as soon as a war of maneuver began.

In operations near Cherbourg, a single British

division, the 51st Highland, on a single day,

August 18, 1944, reported 40 separate attacks by

friendly aircraft (more than occurred during the

entire Persian Gulf War).28

On August 7, 1944 during OperationTOTALIZE—

a franticly paced and fluid attempt to cut off a

21 Cited @ Mm H~~gs, over/oral: D.Day, June 6, 1944 (New York NY: Simon and Schuster, 1984), p. 254.

22 Blume~oq op. cit., footnote 19, P. 237.

23 Ibid., p. 236.

24 Rob@ L, HeWrit~ ~~~~ ~orSe ~~t~e ~eSfern ~~ont: ~~e ~Iory Of f~e j~t~ ]~~a~fry Djvjsion ~uhingt(l~ DC: hlfillltry Jod PIESS,

1946), p. 37.

25 Russ~~ Weigley, ~~Sen~ower’S f.ieu(enanfS @100mingtou IN: Indiana University press, 1981), p. 170.

26 Hmtigs, op. cit., foomote 21, p. 255.

27 Kent Ro~~ Gree~lcld, ( ‘Ax-DIy Ground Forces md Air-Ground Battle Team, ” Study No. 35 (Historiczd Section: Army Ground Forces,

1948), p. 89.

28 HM~g, Op. cit., fo’o~ote 21? p. 303-
—— ...—.— — — ——. -. —

Chapter 2–Historical Review of the Causes of Fratricide [ 15

huge German force fleeing through Falaise--U.S.

heavy bombers bombed short, causing 300 casualties among British, Canadian, and Polish

ground forces.

A week later, British bombers attacked U.S.

Army forces. The primary culprit was a failure of

inter-allied coordination. U.S. Army units used

yellow smoke to mark their positions while the

Royal Air Force used yellow smoke to mark its

targets. A historian records one witness saying,

"

. . . the more the troops burnt yellow flares to

show their position the more the errant aircraft

bombed them.”29

Sometimes failures of communication have

forced gunners to fire on forces knowing full well

that they are friendly. By the very strictest

definition--that is, willful but mistaken attacks

on friendly forces—this would not be friendly

fire. The German general Guderian recounts how,

during the blitzkrieg into France, Luftwaffe

airplanes attacked his units. The ground units

knew that the airplanes were German but were

forced to return fire in simple self-defense. One

pilot bailed out when flak hit his plane and Guderian

himself was waiting for him on the ground.30

General Omar Bradley recalls that a flight of

American A-36s attacked his armored column in

Sicily. The tankers properly identified the aircraft

as friendly and lit off yellow smoke flares, the

markers for ‘‘friendly’ armor, but the attacks

continued so the tanks returned fire and downed

one of the planes, When the pilot parachuted to

earth, the tank commander said, ‘‘Why you silly

sonuvabitch, didn’t you see our yellow recognition signals?” To which the pilot replied, “Oh. . .

is that what it was? ’31

On August 15, during the breakout from

Normandy, one American fighter pilot had the

bad luck to mistakenly strafe the headquarters of

the XIX Tactical Air Command near Laval.

Antiaircraft gunners knew full well that the plane

was American but again for self-defense were

forced to return fire. Flak brought him down.32

I Fratricide Due to Fire Discipline

Failures

At the lowest level, ‘‘command and control’

devolves into something as straightforward as

“fire discipline.’ Indeed, where command and

control concerns the actions of units, fire discipline

concerns the actions of the individual shooter.

The following case illustrates a string of

mistakes, fire discipline being just one: In the

fighting in France, a group of eight tanks set out

in low visibility in late afternoon of July 9, 1944.

They were under strong pressure from superiors

to make a symbolic advance by the end of the day.

At a critical road junction, the group commander

turned right instead of left, bringing them upon

Company C of the 823 Tank Destroyer Battalion,

later to hold a U.S. record for most German

vehicles killed.

Based on the tactical situation, the company

expected no U.S. tanks to be on that road and the

tanks were approaching from the direction of

German lines; thus the company reasonably

assumed that they were German. The first tank

took a direct hit from a 76 millimeter antitank

cannon and was destroyed. The others continued

to advance and opened fire. At 400 yards, the

defenders recognized the tanks as American. One

very brave sergeant stood up and waved wildly to

get the tanks to stop firing but they kept on. The

defenders stopped firing, took cover, and hoped

for the best. One of the passing tanks shot at an

uncamouflaged halftrack at a range of 15 yards,

wounding a driver. 33 This incident shows that

29 John Terraine, A Time for Courage: The RAF in the European War, 1939-1945 (New York NY: Macmillan, 1985), p. 661.

30 Hek Guderian, Panzer Leader (New York, NY: Duttoq 1952), p. 113.

31 Hallioq op. cit., footnote 15, p. 178.

32 Craven and Cate, op. cit., footnote 9, VO1. HI, p. 255.

33 Sckader, op. cit., footnote 5, p. 82.
. . . . - -- - .- . - . - -- - - -- . - - -- - - —

16 I Who Goes There: Friend or Foe?

!*u);”

n

z<kzr. &. -

.. JCr . . co ‘

z “’w’’”* ‘“ ““”” . . ,4.,,

*OU %, %,;* ‘+, “

Aircraft Spotters’ Guides distributed to troops in the

field during World War II. The most basic

identification system is comprised of the human eye

and the human brain, but these require training to be

effective.

fratricide occurs because of compounded errors;

in this case, starting with poor navigation, poor

communication, and faulty identification, and

ending with lack of fire discipline, since inability

to identify can hardly justify firing at a halftrack

at 15 yards.

Lack of fire discipline was the major contributor to the worst antiaircraft fratricide in World

War II. On July 11, 1943, the beachhead on Sicily

was to be reinforced with a drop of 2,000

paratroops. The troops left Tunisia in 144 C-47

transports. The fleets and ground forces had been

alerted to the drop. The flight went well until,

when crossing over the coast at a very visible but

vulnerable altitude of 1,000 feet, the transports

were fired on by a lone machine-gunner. The

beachhead forces had been attacked just hours

earlier by German bombers and, once the firing

started, discipline collapsed; everyone on the

ground was ‘throwing everything they had at us’

as one airborne company commander later put it.

A destroyer even fired on transports that had

ditched at sea. The results were a disaster. Of the

144 transports, 23 were shot down and 37 damaged. One hundred forty one paratroops and air

crewmen were killed. Many of the transports that

survived did so by scattering; thus, of the original

force of 2,000, only 500 or so could be effectively

organized on the ground in the drop zone.34

Just two days later, the British suffered a

similar incident in their zone of Sicily. Nineteen

hundred paratroops were to capture the Primosole

bridge, but more than half the transports were hit

by either ship- or ground-based antiaircraft fire.

Three hundred men did reach and capture the

bridge. 35

I Fratricide Due to Navigation Failures

Closely related to command and control are the

problems of navigation. During World War II

Pacific fighting and in Vietnam, many artillery

fratricides resulted from forward observers correctly calling in fire relative to their putative

positions, but not knowing their own locations

precisely. 36 This seems characteristic of jungle

fighting, when forces could go long periods

without knowing just where they were. The

Marine Corp still refers to “The Battle of the

Tenaru River’ (on Guam), which actually took

place on the Ilu River, but because the maps were

so poor and the vegetation so thick, the men on the

ground did not know that at the time.37

34 (XUlo r)’)ZSte, Bitter Vic(ov: The B~tr/e for Siciliy, Ju/y-A~g~Sr J$)43 mew York NY: William cobs, 1988), pp. 307-308.

35 A&fiGml~d ~dHowmd smy~,si~i/y ~~thesurrenderof]taly (was~gtou Dc: Us. Army, Office of the Chief of Military History,

1965), p. 218.

36 Sckader, op. cit., footnote 5, p. 23.

37 ~fim stew- Gw&l~ana[: World War II’S Fier~e~t Naval campaign (@redo% l%gl~d: Willi~ Kimber, 1985), p. 50.
Chapter 2–Historical Review of the Causes of Fratricide I 17

Navigation, not identification, clearly was the

problem when Navy dive-bombers were called in

to attack Japanese defenders on the tiny island of

Tanambogo. The planes bombed the wrong

island, adjacent Gavutu, killing three Marines and

wounding nine others.

Navigational blunder was responsible for mistaken aerial bombing of civilians in World War II.

One of the earliest incidents was a German error.

On May 10, 1940, 20 Heinkel 111s set off to

bomb Dijon. One Luftwaffe lieutenant got separated from the group due to bad weather. When a

city suddenly appeared below, he took it to be

Dijon and bombed it but it turned out to be the

German town of Freiburg. (Instantly, the Ministry

of Propaganda announced that Allied aircraft had

initiated a deliberate policy of ‘terror bombing, ’

with the innocent citizens of Freiburg as the frost

victims. )38 In general, however, these sorts of

gross navigational error rarely caused fratricide in

World War II.

H Fratricide Due to Identification

Failures

Finally, many fratricide are due to straightforward misidentification. The first aircraft used in

combat in World War I did not even display

national insignia. When German ground fire

brought down a Zeppelin on August 23, 1913, the

Germans painted Iron Crosses on all their aircraft.

The British adopted markings too, but quickly

learned that gunners confused the Iron Cross and

the Union Jack insignia so they switched to red,

white, and blue roundels similar to those used by

the French at the time.

Oftentimes an observer sees what he is looking

for, not what he is looking at. The “scientific

method’ calls for first forming a hypothesis and

then searching for evidence that it might be

wrong. Psychological tests show that people

recognize things in the opposite way, by forming

L

o

A World War II classroom for training sailors in the

identification of naval ships and airplanes.

a hypothesis and then searching for additional

evidence that it is correct.

On May 15, 1941, a formation of Fairey

Swordfish took off from the British carrier Ark

Royal as part of the epic search for the German

battleship, Bismarck, They soon spotted a large

warship and launched torpedoes against it. But it

was the cruiser HMS Sheffield, a ship that did not

look anything at all like the Bismarck. A historian

wrote, “Expecting to see the Bismarck, Bismarck

is what they saw. ’ Fortunately, skillful evasion

by the Sheffield ensured that the torpedoes

missed, One Swordfish pilot radioed, ‘‘Sorry for

the kipper. ’ ’39

Seeing what one expects to see accounts for a

particularly dangerous opportunity for fratricide:

patrols returning to friendly lines. Since scouts

and patrols are coming from the direction of the

enemy, getting past friendly, but nervous, guards

and lookouts can be tricky. Thomas ‘‘Stonewall’

Jackson went ahead of his own troops to reconnoiter Union lines during the Battle of Chancellorsville. Just as Jackson was returning to confederate lines, forward units of General Joseph

Hooker’s Union infantry reached the North Carolina troops near Jackson. Some shots were fired

and the hastily dug-in Confederates were greatly

38 Wolfgmg Dierich, Kampfgeschwa~er “Edelweiss”: The History of a German Bomber Unit (Londou England: 1~ Men, 1975), p. 26

39 Ludovic Kennedy, F’ursuir: The Chase and Sinking of the Battleship Bismarck (New York NY: PinnaCle, 1975), pp. ls~lss.
. . . . . . . . . . . . . . . . .

18 I Who Goes There: Friend or Foe?

I

● A 1 \‘ ‘ ‘“l +’ 10

-k a-+

; \ z

—wr’w--* \

01’

World War 11 troops were given free packs of Airplane

Spotter Playing Cards. Maintaining good

identification skills requires constant practice,

excited by anticipation of the oncoming assault.

Hearing the firing, Jackson hurried back toward

his own lines but under the nervous conditions a

forward Confederate picket—seeing riders approach from the direction of known enemy

forces—shot and mortally wounded the general.40

Some admirers of Jackson argue that his death

changed the course of the war, which, if true,

would make it the fratricide of greatest consequence uncovered during this research.

Misidentification due to similarities between

weapons are more understandable. Many friendly

fire losses during the Battle of Britain were

attributed to the similarity of the Supermarine

Spitfire Mark I and the Messerschmitt Me-109E

fighters. Also, the Bristol Blenheim twin-engine

fighter resembled the German Junkers Ju88

medium bomber. The latter similarity lead to the

destruction of three Blenheims. One section of

Canadian Hurricanes, thinking that the planes

below them were Junkers, attacked but pulled

away at the last second when the leader realized

his mistake. The next section still went in for the

attack, in part because they mistook the yellow

and red Very recognition flares for tracer fire from

machine-guns. One Blenheim blew up in the air

and the other two crash-landed.41

During World War II, considerable effort and

attention went to improving identification of

aircraft. As one response, the British developed

electronic IFF devices. A touring “air circus”

was also organized so ground forces could

practice identifying real aircraft overhead, not

resin models in a classroom.

TACTICAL CONSTRAINTS DUE TO FEAR

OF FRATRICIDE

At times in the past, fratricide has been

accepted as a costly necessity of combat. For

example, World War I tactics made some fratricide almost inevitable. Trench defenses could be

captured if the defending machine guns were

suppressed by artillery fire while the attackers

approached the trench works; thus, the attackers

wanted the artillery to pound defensive positions

up to the last second. In this situation, attackers

were willing to have friendly artillery fall very

close because they believed that the losses due to

fratricide would probably be less than those from

enemy machine-gunners .42 A World War II battalion commander said, “We must teach our

soldiers to remember that when they follow the

artillery barrages and air strikes closely, they

40 G,F.R. Hendersoq stonewall Jackson and the American Civil War (New Yorlq NY: Da GPO, 1988), P. 678.

41 Ricmd Collier, Eagle Day (New York NY: AVO~ 1%9), p. 140.

42 For ample, ~m ~ V+ Hogg, Ba~age: the Gum in Acfi~n (New York ~: B~lentine BOOkS, 1970), p, 21, “me Frenck With their

greater elan and still-unconquered spirit of attack at all costs, were known to observe that unless the infantry suffered 10 pereent casualties from

their own artillery, they weren’t following the barrage close enough!” or”. . the ‘creeper’ [rolling barrage] covered the ground progressively

in front of and behind the objectives. All the infantry had to do was to stay close to it even if the occasional short round sprayed them with

shrapnel.” from Shelford Bidwell and Dominick Graham, Fire Power: British Army Weapons and Theories of War, 1909-1945 (Imndo~

England: Allen and Unwiu 1982), p, 111.
——.—

Chapter 2–Historical Review of the Causes of Fratricide 19

eventually suffer fewer casualties even though an

occasional short may fall on them. ’ ’43

Yet no commander can afford to be indifferent

to fratricide and avoiding it can limit tactical

options. For example, the need to insure safety of

infantry operating with artillery severely hampered the flexibility of the massive British battle

plans for the great World War I attack at the

Somme.

Fratricide has a greater cost than the direct

combat loss of the forces hit. Fear of fratricide can

so inhibit a commander’s actions that combat

efficiency is much reduced. The Center for Army

Lessons Learned (CALL) reports several consequences of fratricide incidents that reduce combat

effectiveness.44 These are listed in Table 2-1.

In addition, friendly fire does not need to kill to

have a suppressive effect. In some instances, for

example in World War II battles on the islands of

Biak and Luzon, groups of infantry as large as

battalions spent whole afternoons pinned down

by friendly fire of various sorts, seriously disrupting coordination of attacks.

Nighttime World War 11 naval battles are filled

with cases of tactical confusion in general and

fratricide in particular. During the Battle of Cape

Esperance, control broke down from the start with

the charge of the destroyer Duncan, described

above. The situation became so confused so

quickly that the American group commander,

Admiral Scott, ordered ‘‘Cease firing, our ships!

Scott further ordered that ships flash their recognition light (colored lights up either side of the

bridge) .45

The Americans’ problems with sorting out the

situation benefited the Japanese enormously.

Firing was halted for four minutes. This may not

Table 2-l—Detrimental Effects of Fratricide

● Hesitation to conduct limited visibility operations

. Loss of confidence in unit’s leadership

● Increase of leader self-doubt

● Hesitation to use supporting combat systems

● Oversupervision of units

● Loss of initiative

● Loss of aggressiveness during fire and maneuver

● Disrupted operations

● Needless loss of combat power

● General degradation of cohesion and morale

SOURCE: Center for Army Lessons Learned.

seem like much until considering that the heavy

cruiser Salt Lake City had fired 80 eight inch

rounds in the first two minutes of the battle and

the light cruisers were averaging an incredible

150 rounds a minute each—so four minutes was

a long time. Furthermore, the signal lights revealed the ships’ locations to the Japanese.

Finally, the lights identified the U.S. ships for

the Japanese. Ironically, their commander, Admiral Goto, had thought that he was under mistaken

attack from another Japanese force and had been

hesitant to return fire, but the distinctive recognition lights showed the force to be American.

Within an eight minute period shortly after

midnight, Scott ordered recognition lights to be

flashed three more times. The group was never

completely under control and both sides withdrew

without a clear decision.

During the Battle of Savo Island in the early

morning hours of August 9, 1942, the crew of the

heavy cruiser Vincennes believed that she was

coming under friendly fire so she hoisted a huge

American flag up the mast. The Japanese assumed

that this must mean that she was the flagship and

therefore concentrated their fire on her. Two

minutes later, Japanese cruisers took the U.S.

destroyer, Ralph Talbot, under fire. Her skipper,

43 Sctiader, Op, Cit,, foo~ote 5, p. 17. Also from footnote 53 of Cbptcr one of Sctider: ‘‘An experienced infantry officer who send as

a battalion S-3 in Vietnam related to the author that it was his common practice (and that of others) to accept up to 5 percent friendly casualties

from friendly artillery in the assault before lifting or shifting f~es. The rationale, of course, is that it is preferable to suffer 5 percent easuahies

from one’s ovm fire plus 5 percent from the enemy than to permit the encmy, through lack of adequate suppression, to inflict 15 percent

casualties on the attacking force. ’

44 Center for Army ~ssom~ ~amed, Fratricide Risk Assessment for Company Leadership, CALL H~dbook No. 92-3 @ofi ~avenwo~

KS: Center for Army hssons Learned, March 1992), p. 4.

J5 Udcss o~cWise cit~ the following naval accounts arc from Kilpatrick, op. cit., footnote 10.
. . -— . - - . - . . - -

20 I Who Goes There: Friend or Foe?

Lt. Commander Callaham, also believed that he

was being fired on by friends so he turned on his

recognition lights. This action was so unexpected

that the Japanese were momentarily flummoxed,

worrying that perhaps they were firing on another

Japanese ship. The Japanese cruisers were forced

to use search lights to illuminate the Talbot. She

took several hits but escaped into a squall.

Nearby, on August 21, again in the early

morning darkness, the U.S. destroyer Blue and the

Japanese destroyer Kawakaze detected one another at almost the same time. The American ship

was equipped with radar, which the Japanese had

deployed on only a very few ships-and those

units were primitive. For night fighting, the

Japanese relied instead on specially trained lookouts equipped with oversized, night-use binoculars. During clear weather, the Japanese visual

method was as good as U.S. radar. In this

particular case it was better. For whereas the Blue

detected a blob on a radar screen, the Kawakaze

detected and identified target. Thus, as the Blue

was creeping forward to get a better view, the

Kawakaze was launching 21-inch diameter "Long

Lance” torpedoes that ripped the stern off the

American destroyer. She was later scuttled.46

During the closing moments of the Battle of

Empress Augusta Bay, the cruiser Montpelier

received direct orders to fire at a target at

specified coordinates. In the pre-dawn darkness,

the Montpelier’s commander was uncertain of the

target and intentionally directed that the first

salvo should miss. He then listened in on the TBS

(Talk-Between-Ships) radio for two minutes and,

failing to hear any complaints, commenced firing

to hit. This time, the incoming rounds quickly got

the attention of the target, which turned out to be

the American destroyer Spence. Radio calls for a

cease fire were heeded before any damage was

done but, clearly, the lack of identification

required a tactical solution that would have given

some advantage to an enemy, either a chance to

evade further fire or return fire.

Caution induced by fear of fratricide can be

exploited by an enemy. During World War II,

artillery fire began the preparation for an attack by

the 3rd Infantry Division against the town of

Osheim on January 23, 1945. The leading battalion reported that shells were landing on their

position and the barrage was halted. More range

was added and the barrage resumed but rounds

still fell on the lead battalion. Finally, the

Americans discovered that the fire was coming

from nearby German tanks that held their fire

until the barrage started, specifically to fool the

Americans into believing they were receiving

friendly fire and so trick them into calling a halt

to the barrage. (Incidently, the 3rd Division later

adopted rules that called for finishing planned

barrages regardless of reports from forward units,

which may have contributed to later fratricides.)47

The Japanese also used the technique of

synchronizing the artillery fire with their enemy

artillery, although perhaps for different reasons.

On Guam and elsewhere in the Pacific theater,

Japanese artillery and mortar crews would wait

until U.S. artillery was firing before firing their

own guns, thus increasing the difficulty of locating them by their sound. In addition, of course,

U.S. troops noticed that when U.S. artillery fired,

they often received incoming rounds, causing

them to believe it was friendly fire.

THE PREVALENCE OF FRATRICIDE

Any conclusions about the general prevalence

of fratricide developed from a collection of

anecdotes must be regarded with healthy skepticism. Several sources use a figure of two percent

of casualties that have been due to fratricide in

46 stew~, op. cit., foo~ote 37, p. 50.

47 Sctiader, op. cit., footnote 5, p. 9.
——..——.

Chapter 2–Historical Review of the Causes of Fratricide I 21

20th century wars. In fact, the two percent figure

seems to have become almost a rule of thumb.48

One of the great difficulties is knowing who

fired which shot. Only rarely is reliable evidence

available, but it is sobering to discover that when

evidence is there, it often reveals fratricide that

participants at the time were unaware of. Two

cases from the same campaign provide interesting

examples. The reader has doubtless noticed that

many examples used here come from the Solomons naval campaign. This is not surprising when

one considers that many of the major battles there

took place at night, resulting in poor coordination

and frequent misidentification. But the same

conditions that made mistakes likely made it

unlikely that they would be detected.

In one case, however, U.S. friendly fire left a

clear fingerprint. U.S. warships carried a limited

supply of ‘‘dye-loaded” shells, with each ship

carrying a different color. The added dye allowed

two ships shooting at the same target to distinguish the splashes of rounds hitting the water and

thus independently adjust their fire. When the

light cruiser Atlanta’s crew examin ed battle

damage after nighttime engagements off the coast

of Guadalcanal, they discovered nineteen hits

from eight inch shells loaded with green dye, the

color of the heavy U.S. cruiser San Fransisco.

The depleted-uranium rounds used by U.S.

tanks during the Persian Gulf War left a similar

telltale and again, fratricide rates turned out to be

higher than previously suspected. That combat is

discussed further in the last section of this

chapter.

Perhaps the best estimate of overall rates of

fratricide come not from traditional military

histories and action reports but from the medical

records. The U.S. military has long kept records

of the causes of casualties. Unfortunately, the

normal reports lack enough detail to determine

conclusively that a casualty was caused by

friendly free. Moreover, without a detailed accounting of all casualties in a given time or place,

we cannot know the numerator and denominator

needed to calculate the fraction of casualties

caused by friendly fire.

In a few cases, starting in World War II,

however, detailed casualty surveys have been

carried out that allow a reliable estimate of the

frequency of friendly fire losses in those cases.

The frost was conducted by Dr. James Hopkins,

who maintained detailed records of cause of

wound for every casualty in his batallion. He

served for part of the war on New Georgia

Island-near Guadalcanal--and part in Burma.

He examined the wounded and conducted interviews after actions. Hopkins was able to determine that 16 percent of those killed and 19 percent

of those wounded were the victims of friendly fire

by his broad definition, which includes accidents

in the use of weapons.

49 By TRADOC’s current,

narrower definition, as applied by Dr. David

Sa’adah of the Department of the Army, Surgeon

General’s Office, the figures would be 13 percent

and 14 percent.50

Two other comprehensive surveys examined

all of the casualties from two divisions in

Bougainvillea, in the South Pacific, in 1944.

Almost a hundred of the killed were more

carefully examined by autopsy to determine cause

of death.51 These surveys reveal that 24 percent of

48 See CJCtiader, ~p ~lt,, foo~ote 5, ~, 105; Trevor Duprey, At~ition: Forecasting Battle cas~[h’es a&Equip~nt~sses in Modern War

(Fairfax, VA: Hero Books, 1990), p. 3; and Dwight Dickson and Ehin Hundley, “Avoiding Not So Friendly Fire,” Military Review, July 1992,

p. 57.

49 James Hopkins, ‘‘Casualty Survey-New Georgia and Burma Campaigns,‘‘ in James C. Beyer, cd., Wound Ballistics (Washington DC:

Office of the Surgeon General, Department of the Army, 1962), pp. 237-280 from the series, Medical Department, United StatexArmyin World

War 11, Colonel John Lada, Editor in Chief.

50 see colonel David M. SaJa&@ Office of & Sugeon Gen~~, Headquarters, Dqartment of the Army, “Friendly Fire: wi~ we &t It

Right This Time?’ p. 7.

51 As~ey W. Oughterson et. al., ‘‘Study of Wound Ballistics-Bougainville Campaign, “ in Beyer, ed. op. cit., footnote 49, pp. 281-436.
22 I Who Goes There: Friend or Foe?

the deaths were due to fratricide, using the

narrower current TRADOC definition.52

In Vietnam, only the United States and its allies

had certain types of weapons, for example,

air-delivered ordnance of any sort-especially

napalm, certain types of artillery, and so on. Thus,

by examining the wounds of casualties and

determining g the type of weapon that caused them,

one can estimate the fraction that are caused by

friendly weapons. Using this approach, some

unpublished reports cited in the press estimate

that perhaps 15 to 20 percent of the casualties in

Vietnam were fratricides.53

The U.S. Army also conducted careful casualty

surveys during the Vietnam War that were

compiled in the Wound Data and Munitions

Effectiveness, or “WDMET” study. The data

were collected between 1967 and 1969 from

elements of one cavalry and three infantry divisions. An absolute figure for fratricide is not

available from the WDMET survey. However, the

data include the type of weapon causing the

injury, and in four cases the type is very specific

and was almost certainly in the hands of U.S.-or

at least allied-troops: the M16 rifle, the M79

grenade launcher, artillery (excluding mortars),

and Claymore mines. These four weapon types

alone accounted for 11 percent of all U.S.

casualties, including 10 percent of the fatalities.54

The summary of the data compiled by Colonel

Sa’adah is shown in table 2-2.

These casualty surveys cover only limited

cases for which data are available, but again it is

worthwhile to note that in every case where data

are available, the fratricide rate is significantly

higher than the two percent that frequently

appears in print as the nominal fratricide

rate. 55

Despite the hit-and-miss of using historical

anecdotes, the types of fratricide do show some

patterns. As might be guessed, indirect fire

weapons or long-range weapons (in past wars,

artillery and bombers) have been more likely to be

responsible for friendly fire. Also, the damage

done by these weapons is disproportionately great

because mistakes involving single-shot weapons,

like tank guns, kill one friend at a time, while

artillery barrages and bomber attacks can devastate whole units. The Persian Gulf war did not

have any artillery fratricide. This may be good

luck or reflect an important change brought about

by better communication and navigation.

Perhaps surprisingly, there seems to be no

strong correlation between type of action and

likelihood of fratricide; it is just as likely during

offense or defense. Fratricide between neighboring units appear to become more likely the greater

their separation in the chains of command.

Whenever units operate near one another and

have poor communication, poor navigation, or are

poorly controlled, fratricides can occur.

Fratricide of almost any type are more likely

during periods of limited visibility when identification is harder. However, although better identification is frequently presented as the solution to

friendly free, Schrader classified only about a

quarter of the cases in his review as due primarily

to misidentification. The majority of fratricide

were more properly explained by failures of

command and control or fire discipline. See figure

2-1.

52 sa’~~, Op. cit., footnote 50, p. 8.

53 David M~rnS~~ ~~FWS Not he CMy hatin he GuM WU,’ Nationul Journa/, Feb. 9, 1991, p. 335, cittig tie work of Colonel David

HackWorth.

54 Sa’adti, op. cit., footnote 50, p. 10.

55 D~g tie Coww of ~~ ~~e~~ment, tie au~or ~~d seve~ oppo~ties to coll~t perso~ WCOUIItS from military perSOMel that

served in Vietnam. This is admittedly a totally umcientilic sampling but the clear concensus is that a 2 percent fratricide rate is a serious

underestimate. See also app. A in Colonel Sa’adah’s paper, ‘‘The 2 Percent Nonsense. ’
Table 2-2—Friendly Fire Data in Combat Casualty Surveys—World War II Through Operation Desert Storm

No. of cases KIA + DOW WIA by Prevalence: Prevalence:

Survey location/name No. of cases KIA + by friendly f ire friendly fire survey TRADOC

forces in survey Line in survey DOW WIA No. % No. % definition definition

New Georgia and Burma/Hopkins

Jungle perimeter defense

July 18-Aug. 5, 1943,

Spearhead across Burma,

Feb. 15-June 8, 1944

Bougainvillea Beachhead perimeter

defense

Feb. 15-Apr. 21, 1944

Bougainvillea autopsy

Mar. 22-Apr. 21, 1944, 25% of all

KIA + DOW within Bougainvillea survey

Vietnam WDMET

Components of 5 Army divisions

June ‘67-June ’69, preferably in

offensive engagements

Vietnam WDMET autopsy

July ‘67-Nov. ’68, 500 consecutive

autopsies within VN WDMET

All U.S. Forces, Jan. 17-Dee. 15, 1991

Operation Desert Storm

l a

lb

2a

2b

3a

3b

4a

4b

5a

5b

6a

6b

370 102 268 16 16 50

353 99 254 13 13 36

1,788 395 1,393 63 16 156

1,778 392 1,386 60 15 149

99 99 0 30 30 0

91 91 0 22 24 0

5,993 1,279 4,714 NC NC NC

5,993 NC KIA+DOW=WIA=667

500 500 0 NC NC o

500 500 0 51 10 0

613 146 467 35 24 72

613 146 467 35 NC 72

19 17.970

14

11 12.3%

11

0 Not computed

o

NC “almost

certainly more

than 10%”

o Not reported

o

15

NC Not reported

14%

12%

24%

11%

10940

17%

Within each survey, Line a displays the data as presented in the original study. Line b standardizes this same data to the current TRADOC definition of “fratricide.”

KEY: DOW = died of wounds; KIA = killed in action; WIA = wounded in action; NC= not calculated.
—. -.—. .

24 I Who Goes There: Friend or Foe?

Figure 2-1 —Causes of Fratricide: Direct Fire

Fratricide in World War II, Korea, and Vietnam

Inexperience

19“/0

(’- Unknown factors

Target 10%

misidentification

260/o

\/

Coordination

45%

“,0 = Incidents by category

58 total Incidents

SOURCE: U.S. Army

THE NATIONAL TRAINING CENTER

Data collected from the National Training

Center (NTC) at Fort Irwin, California are important enough to warrant special notice. The Army

maintains training centers where visiting units

can engage in mock combat with “OPFORS’ or

“opposing forces. ” The NTC is of particular

interest because it has been equipped with a

sophisticated laser direct-fire engagement system

called the Multiple Integrated Laser Engagement

System, or MILES. The NTC is also equipped

with location and engagement recording systems.

\ Guns on tanks, infantry fighting vehicles, even

personal rifles, are equipped with lasers. When

the gun ‘fires’ a blank round, the laser also fries.

Each of the major weapons and each of the

personnel have detectors that sense when a laser

“hit” occurs.

The laser pulses are coded in such a way that

I

the detectors know the type of weapon that freed.

Thus, if a tank detects that it has been shot by a

rifle, nothing happens; but if a rifleman’s sensor

detects that he has been shot by a tank, his sensor

registers a‘ ‘kill.’ A kill is signified by activating

a flashing light. Each shot and each hit activates

a small radio pulse indicating type of shooter and

target, which is picked up by antennas spaced

around the training center. These data are recorded along with their time, and data are

analyzed by computer after each exercise to

explain to the participants various mistakes that

were made.

The Army emphasizes that its training centers

are for training, not experimenting or data collecting, so the system has not been set up with

fratricide data collection in mind. It nevertheless

provides invaluable insight into the causes of

fratricide. Some questions arise about the relevance of the data since these are not real battles so

perhaps the participants do not behave the way

they would in actual combat. Nevertheless, the

data are enormously rich compared to information about real battles, so if one believes the

simulation valid, the data are proportionately

useful. One can then try to examine hits caused by

friendly fire and hope to learn something of the

circumstances.

Much of the following is taken from a brief

RAND study that evaluated data from 83 battalionsized battles.56 See figure 2-2. Considering the

causes of the fratricides observed, the study

states:

Of the 18 cases of fratricide, one-half could

have been prevented had the shooting vehicle

been aware of the location of a sister organizational unit, for the destroyed vehicle was located

in a friendly formation with no enemy nearby.

Another third of the cases could have been

prevented if the shooter had knowledge of the

location of individual isolated friendly vehicles,

a more difficult requirement. One-sixth of the

cases involved the killing of a friendly vehicle

while close to opposing force (OPFOR) elements.

I

56 M~~GoldSfi@APplying the National Training ce~terExpen”ence-Incidence ofGround-to-GroundFratricide, R4ND Note N-2438-A

(Santa Monica, CA: The Arroyo Center, R4ND Corporation February 1986).
Chapter 2–Historical Review of the Causes of Fratricide I 25

In this class, only an Identification Friend or Foe

(IFF) device could provide the information necessary to positively avoid fratricide.57

The data indicate that at least 1 percent of the

“blue” vehicles killed were killed by friendly

direct fire. This figure is much less than in the

Persian Gulf War. Two possible biases may

explain the difference. The NTC data may underestimate some fratricide. For example, if the

lasers cannot penetrate through dust, then no kill

is recorded even though a tank round would have

scored a hit in actual battle. This effect works to

reduce hits from enemy attacks as well as

fratricidal attacks, but since fratricide is more

likely to occur in dustier conditions, it might be

under-recorded to some degree. In addition, the

OPFOR train all year long on the same ground

and are excellent troops (according to their own

evaluation, not just good but the best). Thus, total

blue “casualties” are usually high in the simulated combat, unlike the Persian Gulf experience,

and the resultant ratio of friendly fire casualties to

total blue casualties unusually low.

Artillery cannot be simulated with MILES but

other means are available, The data available

indicate that 3.6 percent of artillery fire missions

resulted in some fratricide. This result appears

worse when one considers that only about a third

of the artillery missions hit anything at all, friend

or enemy. Thus, of those artillery fires that hit

anything, about one-tenth hit friendly forces.

Experience at the NTC also suggests that fratricide resulting from artillery-delivered mines and

unexploded submunitions may be almost as

serious a concern as other artillery fratricides,

although the MILES data do not now allow a

quantification of this effect.

Some fratricides were clearly caused by misidentification but more were due to disorientation.

(This result depends on the terrain; preliminary

unpublished data from a similar test facility in

Figure 2-2—Types of Information Needed to Avoid

Fratricide: Direct Fire Fratricide at the

National Training Center

IFF

Location

blue vehl(

330/0

\

/

--=’’’’’ ~catlonof

blue units

50%

“,0 = Number of incidents by cause

77 total incidents

SOURCE: U.S. Army.

Hohenfels, Germany suggests that disorientation

is not as important there as misidentification.

However, the German test range is much smaller

and some nearby hills apparently provide easy

orientation landmarks.) Several fratricides at the

NTC occurred when no enemy forces were nearby

and, moreover, the commanders knew that enemy

were unlikely to be near.58 These cases could be

cured by better fire discipline. Mistakes due to

true misidentification were most common in

melees and poor visibility.

The data collected at the NTC is now being

exploited for fratricide ‘‘lessons-learned.’ Most

of this work is now coordinated through CALL,

or the Center for Army Lessons Learned, part of

the U.S. Army Combined Arms Command at Fort

57 Ibid., p. vi.

58 Ibid., p, 13,
26 I Who Goes There: Friend or Foe?

Leavenworth, Kansas.59 Since the Persian Gulf

War, observers at the NTC have had to fill out

fratricide incident reports whenever MILES detects friendly free. Preliminary unpublished results show that observers on the ground attribute

fratricide most often to identification failure, but

that this accounts for just over a fifth of the cases,

with another fifth due to failures of command and

control, another fifth due to planning failure, and

a combination of communication and navigation

problems and simple mistakes making up the

balance. Incorrect assessment of the tactical

environment was cited as the most common

contributing cause.

MILES is being expanded at other training

centers and will no doubt provide increasingly

valuable information about how fratricides occur

and can be avoided.

FRATRICIDE DURING THE

PERSIAN GULF WAR

The current surge in interest in fratricide is due

largely to the experience of the recent Persian

Gulf War. Wars are complex and no two are

identical, so “lessons” from the war should not

be considered universal truths. Although many

conditions in the Persian Gulf were special, some

argue that this war was a first example of the

“high tech” wars of the future. It may also be

representative of a type of war that will be more

common for the United States in the future: one

in which massive, overwhelming force is applied

quickly and decisively. A primary appeal of these

types of actions is that U.S. casualties are

potentially very low considering the scale of the

military operation. This report has pointed out

already that one reason the fraction of casualties

due to fratricide was high is that total U.S.

casualties were so very low. Another way of

looking at this is that if low casualties are

characteristic of an important class of future

conflict, then the relative importance of fratricide

will be much greater.

There were 615 U.S. battle casualties in Operation Desert Storm, 148 of which were fatal. Of the

148 fatalities, 35-or 24 percent—were caused

by friendly fire. Of the 467 nonfatal battle

casualties, 72--or 15 percent—were caused by

friendly free. These percentages seemed high at

the time when compared to those assumed from

wars past but the review of past rates of fratricide

suggest that there has been a substantial underappreciation of the rate of fratricide in past wars.

Of the 35 soldiers killed by friendly fire, seven

were on the ground while the 28 remaining were

in vehicles. This distribution reflects the highly

mobile, mechanized nature of the combat—that

is, most U.S. forces were in vehicles so one would

expect more casualties there-but it is also

hopeful for those seeking a technical solution,

since mounting combat identification equipment

on vehicles is much easier than mounting it on

individual infantrymen.

A case-by-case description of the known fratricide incidents is listed in table 2-3.60 F e w

individual cases stand out as being unique to the

modern equipment used in the Persian Gulf War.

In one instance, a radar-seeking missile lost track

of the Iraqi radar for which it was intended

and-while attempting to reestablish a target

track-locked onto a nearby U.S. radar. This type

of technology-dependent mistake is, however, the

exception; many of the descriptions of friendly

fire—with a change of weapon designation—

could have taken place in the deserts of North

59 At he tie of ~~ ~~g, c~’s mse~ch iss~ ~ titform ~d ~published but their results seem so far to confkn the ~ work.

Major Rick Bogdeu personal communication, February 1993.

@ ~s ~omation is ~en from “W@ Robes Friendly Fire Incidents, ” a news release from the Offke of the Assistant Secretary of

Defense (Public Affairs), dated Aug. 13, 1991. Note that some of the incidents are not ‘‘fratricide’ by the narrowest definition now used by

the Training and Doctrine Cornmand. For example, casualties due to faulty missiles or artillery rounds would be considered accidents because

they did not result from a deliberate act of ftig, believing one was firing at the enemy.
Chapter 2–Historical Review of the Causes of Fratricide I 27

Table 2-3—Persian Gulf Friendly Fire Incidents—1 991

Ground-to-Ground

January 29-Four Marines were

killed when their Light Armored

Vehicle (LAV) was struck by a

TOW missile which was fired

from another LAV west of Kafji,

Saudia Arabia.

February 14-Three soldiers

were wounded in a small arms

exchange during urban clearing operations in the town of

Arky Amah Al Jadid, Saudi

Arabia.

February 24-One Marine was

killed when the convoy he was

in received fire from a tank.

February 26-Three soldiers

were killed and three wounded

when their armored personnel

carrier (APC) was hit by machine gun fire from a tank.

February 26-One soldier was

killed when his vehicle was hit

by a premature burst of an

artillery round.

February 26--Five soldiers were

wounded when their Bradley

Fighting Vehicle (BFV) was incorrectly identified and hit by a

TOW missile.

February 26--Two Ml Al Abrams

tanks were hit by fire from

another M 1 Al tank. No casualties occurred.

February 26-Two soldiers were

killed and six wounded when

their BFV, which was operating

in reduced visibility, received

fire from a M1A1 Abrams tank.

February 2&Two BFVs, while

operating at night in reduced

visibility, were fired upon by a

Ml Al tank. No casualties occurred.

February 27—Six soldiers

were killed and 25 wounded

when five M1A1 tanks and

five BFV’s engaging enemy

forces were incorrectly identified at night in reduced

visibility and engaged by

other M1A1 tanks.

February 27—Two soldiers

were killed and nine were

wounded when three BFVs

were fired upon by a M1A1

tank because of incorrect

identification.

February 27—Three damaged M1A1 tanks were deliberately destroyed by other

Ml Al tanks to assure they

could not be used by the

enemy.

February 27-One soldier

was killed and one wounded

when 2 BFV’s were incorrectly identified at night in

the rain and fired upon by a

Ml Al tank.

February 27-One soldier

was killed and two were

wounded when two BFV’s

were hit by fire from a M1A1

tank while operating in rain

and smoke at night during

an attack on a bunker complex.

February 27—Two soldiers

were killed and two wounded

when their BFV was fired

upon by a Ml Al tank while

operating at night in reduced visibility.

February 27----One soldier

was killed and one wounded

by machine gun fire when

they were incorrectly identified as Iraqi forces.

Air-to-Ground

January 23-A USAF A-10

Thunderbolt fired on a Marine observation post with

no casualties.

January 24--One Marine

and one sailor were wounded

when a USAF A-1 O strafed

a USMC Hummvee and a

five-ton truck about 60 miles

west of Kafji, Saudia Arabia.

January 29-Seven Marines

were killed and two wounded

when a USAF A-1 O fired a

Maverick missile which

malfunctioned in flight and

hit a LAV,

February 2-One Marine was

killed and two were wounded

during an air attack by a

USMC A-6E using 500-

pound bombs after their vehicles were incorrectly identified as Iraqi.

February 2—Two soldiers

were wounded when a HARM

missile fired by a USAF

F-4G Wild Weasel did not

properly acquire its intended

target and locked onto the

soldiers’ radar.

February 4-A HARM missile is suspected to have

landed close to the USS

Nicholas (FFG-47) resulting in no casualties and

only superficial damage to

the ship.

February 17—Two soldiers

were killed when a BFV was

struck by a Hellfire missile

fired from an AH-64 Apache

helicopter. Six soldiers were

wounded and aground surveillance vehicle was also

damaged in the incident.

February 23-One Marine

was killed and one wounded

when a HARM missile from

an undetermined source

struck a radar unit.

February 24-A HARM missile is suspected to have

landed close to the USS

Jarrett (FFG-33) with no casualties or damage to the

ship.

Ship-to-Ship

February 25--USS Jarrett

(FFG-33) fired at a chaff

rocket launched by USS

Missouri (BB-63) resulting

in superficial damage to USS

Missouri. No casualties occurred.

March 27—USS Avenger

(MCM-1) received small arms

fire while in the vicinity of

Ras Al Qalayah. No casualties occurred and the ship

moved out of firing range.

Ground-to-Air

February 15-A USN A-6E

pilot reported he was fired

upon by a surface-to-air missile, resulting in no casualties.

SOURCE: Assistant Secretary of Defense (Public Affairs).
28 I Who Goes There: Friend or Foe?

Africa in 1942 rather than the deserts of Iraq a half

century later.

In one barely avoided fratricide, a group of

tanks was waiting for a second unit to catch up.

Radio communication confirmed that all of the

second unit’s forces were behind the frost unit.

Two Iraqi T-55 tanks crossed in front of the first

unit, which quickly destroyed the enemy tanks.

Just minutes later, two more armored vehicles

were detected, moving in the same direction as

the original T-55s. From consideration of the

tactical situation, they obviously seemed part of

the same Iraqi group. An alert tank gunner

noticed, however, that the vehicles showed on the

thermal imager the characteristic ‘hot wheels’ of

U.S. infantry fighting vehicles and called out to

hold fire. In fact, these were the scouts from the

other units reported behind-but showing up

ahead of—the first unit and reported heading

north but actually going west, which unfortunately was the same direction as the nearby

enemy force.61

Another case did not turn out so well. Two

units were traveling at night in parallel but not in

constant visual contact because of a gentle rise

between them. The units passed on either side of

an Iraqi infantry force armed with rocketpropelled grenades. The Iraqis fired at U.S.

infantry fighting vehicles to one side. The explosions were seen by U.S. tanks in the other unit,

which mistook the explosions for gun flashes

from Iraqi tanks. The U.S. tanks returned fire and

hit some of the U.S. infantry fighting vehicles.62

There were no fratricides of airplanes. Air

superiority was so complete and accomplished so

quickly that very restrictive rules of engagement

were possible, which might have hampered the

effectiveness of the air arm but avoided any

fratricide.

SUMMARY

A historian might wince at drawing lessons

from a collection of anecdotes, but some general

points come through. First, fratricide result most

often from a complex chain of errors. The stories

often read: identification was wrong, yes, but

misidentification would have been unimportant if

navigation had been reliable, navigation errors

could have been overcome if communication had

been adequate, and so on. Also, these anecdotes

make clear that while misidentification often

leads to fratricide, failures of command, communication, coordination, and fire discipline are at

least as important. Although an accurate estimate

of the overall frequency of fratricide is impossible

to determine, the two percent rule of thumb

presented by Schrader and others is almost

certainly too low. In every case in which good

data are available, the actual rate of fratricide

turns out to be much higher than two percent and

higher than most would guess. Finally, the types

of fratricide change much less quickly than

military technology. This suggests that technology is only part of the solution; reducing fratricide

will always depend on the trainin g and Skills o f

the combatant in the field.

61 Center for ~y LMSOILS Learned, “Fratricide: Rduchg Self-Inflicted ~ss~,” Newsietrer (April 1992) No. 92-4, p. 1.

62 ~s ~~e is ~-bly sw to one ~cm at the Natio~ ‘Tr~g center, de~ri~ by GoMsmith. h tkit case the fkheS Were

simulated incoming artillery, but friendly units on either side took them to be gun flashes from enemy forces and returned fire.
—. —

I

Avoiding

Fratricide:

A

General

Considerations 3

merica’s recent combat in the Persian Gulf War

brought new attention to an old problem: fratricide.

Twenty-four percent of all U.S. combat fatalities in the

war were caused by friendly fire.1 This figure seemed

much higher than in previous wars and caused a sudden focus on

avoiding fratricide in future wars,

The U.S. military and the American public are becoming

increasingly sensitive to the human costs of military involvement, especially for contests of less than national survival. For

this reason, the United States has invested much in energy and

equipment to keep casualties low. As casualties from hostile

action decrease, the relative importance of fratricide increases

and fratricide should receive more attention.

The previous chapter found that only in a very few cases are

reliable estimates of fratricide available but in each of those

cases, the fratricide rate was much higher than the nominal two

percent rate that frequently appears in the military literature,

Fratricide has been, and probably will continue to be, a

significant source of combat casualties.

Moreover, the political and psychological cost of losses due to

fratricide will always be greater than those due to losses inflicted

by an enemy. In military operations involving allies, fratricide

between countries can cause international friction at a time when

strong cooperation is of utmost importance.2

1 This value derives from 35 friendly fire fatalities out of a total of 148 combat fatalities.

I

I

“Military Probes Friendly Fire Incidents, ” Office of Assistant Secretary of Defense

(Public Afairs), Aug. 13, 1991.

2 During Operation Desert Storrq 9 British soldiers were killed when Maverick

missiles from A-10 ground-attack aircraft destroyed their armored personnel carriers,

causing considerable political controversy in the United Kingdom. See Glenn Frankel,

‘‘In Britain, Fallout from Friendly Fire, ” Washington Post, May 18, 1992, p. Dl,

29
30 I Who Goes There: Friend or Foe?

Fear of fratricide has been a constraint on

combat tactics and maneuvers. The previous

chapter described how lack of effective identification during both World Wars limited the use of

air power for close-in support of ground troops. In

at least one case, danger of fratricide is the

primary constraint on tactics: the joint use of air

defense fighters and air defense missiles in the

same area. Conversely, development of a good,

reliable antifratricide system could open up new

tactical options. Better identification could allow

more rapid attacks on enemy strong points, more

aggressive defense and covering fire by dug-in

second-line defenders as first-line defenders withdraw, closer and more agile air-to-ground or

artillery support, and so on.

Fratricide becomes increasingly important not

just because of its relative increase due to the

smaller numbers of total casualties, but because

of the way that the United States wants to keep

those numbers low. The U.S. military believes

that the best way to win quickly and decisively

with least loss is to apply overwhelming firepower against the enemy. However, if the only

people on the battlefield shooting are Americans,

then it follows that the only way for Americans to

get killed is from fratricide. Indeed, some simple

theories suggest that fratricide may blunt the

advantage of overwhelming advantage in number

(or “force ratio”) so that the U.S. approach to

decisive combat may require solving the fratricide problem to be viable.3

TRENDS IN THE FREQUENCY

OF FRATRICIDE

Some incidents in the Persian Gulf show trends

that may exacerbate the problem of fratricide as

weapons’ development continues to advance.

First, the tempo of battle has increased, oftentimes allowing combatants only seconds to make

life and death decisions. Second, engagement

ranges have increased. Mistakes of identification

were difficult at the close ranges needed in the age

of sword, but many modern weapons’ range far

exceed the range at which the human eye, or even

instruments, can distinguish friends from foes.

Also, the destructiveness of weapons has increased. In the past, fratricidal attacks could

sometimes be stopped if the mistake was realized

quickly, but now the first shot is often fatal,

making an initial mistake irreversible. Finally, a

potential problem often overlooked during the

Cold War is that future enemies may have

weapons similar or identical to those of the

United States or its allies.

Other technical developments make avoiding

fratricide easier. A British investigation early in

World War II showed that among strategic

bomber crews reporting that they had attacked

their assigned targets, only one-fifth had actually

dropped their bombs within five miles of them.4

Absolute rates of fratricide may have peaked in

World War II because the destructiveness of

ordnance increased faster than the ability to

deliver it precisely. Clearly, improvements in

navigation, communication, and weaponsdelivery accuracy improve the control of fire,

making avoidance of fratricide easier (at least in

principle). This hypothesis is supported by experience in Operation Desert Storm where, contrary

to past wars, there were no artillery fratricides.

Since estimates of past rates of fratricide have

been unrealistically low, any telltale that allows

unambiguously attributing a casualty to fratricide

causes a jump in the number of visible incidents.

This accounts for part of the picture coming out

of the Persian Gulf experience. For example, only

U.S. tanks were armed with depleted uranium

(DU) antitank shells in the Persian Gulf. The

shells leave a small but distinctive and easily

detectable trace of uranium on any target they hit.

Thus, after Operation Desert Storm, a quick test

could reveal clearly any fratricide caused by U.S.

3 hwd A. Wojcik, “The Manchester Equations in Defense Policy Analysis,” July 3, 1984, unpublished.

4 John lhai.ne, A Time for Courage: The RAF in the European War, 1939-1945 @Jew York NY: Macmillaq 1985), p. 292
Chapter 3–Avoiding Fratricide: General Considerations 31

tanks. In World War II, the same poor communication and navigation that might cause fratricide

would allow it to occur in the midst of the

confusion of battle without anyone, shooter or

victim, ever realizing it. Today’s improved communication could make fratricide less likely

while also making it more likely to be discovered

when it occurs.

By any absolute measure, fratricide was not

worse in the Persian Gulf War-or in Panama and

Granada-than in previous wars. The fraction of

deaths due to fratricide was apparently high, but

this was due in part to the very low total American

fatalities from all causes and, in part, to past

underestimates of fratricide rates.

MEASURES OF THE SEVERITY

OF THE PROBLEM

Part of the challenge of evaluating any antifratricide effort is deciding on an appropriate measure of how bad the problem is. On the one hand,

the most common—and most public—measure is

the fraction of all U.S. casualties caused by U.S.

weapons; that is, a comparison of the number of

U.S. casualties caused by U.S. forces to the total

number of U.S. casualties.5

On the other hand, some argue that U.S.

casualties caused by U.S. forces are more appropriately compared to the number of casualties

inflicted on the enemy by U.S. forces, In the case

of the Persian Gulf War then, the dozens of

mistaken fratricidal attacks by U.S. forces should

properly be compared to the tens of thousands of

appropriate attacks on enemy targets.6

Comparing friendly fire losses to losses inflicted on the enemy is probably more appropriate

in cases of wars against comparable enemies

where the outcome is uncertain, such as the Cold

War contest between NATO and the Warsaw

Pact. In this case, relative rates of attrition will

determine, in part, which side wins. In contests of

less than national survival, such as the Persian

Gulf War, final victory is less uncertain-if the

Nation is willing to pay the price. The question is

what that price will be in lives lost. In these cases,

casualties should be as low as possible and

military planners should address the causes of

casualties in their order of importance. Thus, in

these cases, comparing fratricide to total friendly

casualties is the more appropriate measure.

Neither of these simple measures is adequate

by itself. Avoiding fratricide is never the sole

objective of a military force; it must be balanced

with other military goals and efforts to hold down

overall human costs. Combat is inherently dangerous and casualties are inevitable, and some of

those casualties inevitably will be due to fratricide. Moreover, some measures to reduce fratricide could be so stringent that they would reduce

military effectiveness and, in the end, increase the

casualties inflicted by enemy forces.7 (See figure

3-l).

Yet a death due to fratricide will never have the

same psychological effect as just another casu5 When possible, this report uses fatalities as a measure of comparison rather than total casualties because of ambiguities of defining

‘‘wounded.

G For example, if the 35 Americans killed arc compared to the 20,000 or more enemy killed in Desert Storm, then the fratricide rate is well

under one percent. See Center for Army Lessons Learned (CALL), “Fratricide: Reducing Self-Inflicted Losses, ” CALL Newsletter No. 92-4,

April 1992, p. 5.

7 This is precisely what some alleged happened during the opening phases of the air war against Iraq, that over-stringent IFF requirements

allowed to go free an Iraqi fighter that later downed a U.S. jet. See Mark Crispin Miller, “Death of a Fighter Pilot, ” New York Times, Sept.

15, 1992, p. 27 and New York Times, ‘‘Officer Says Iraqi Jet Downed Navy Plane During Gulf War, Sept. 15, 1992, p. 5. The Department

of Defense is uncertain but believes that the airplane was downed by a surface-to-air missile. See the rebuttal letter from Pete Williams, Assistant

Secretary of Defense for Public Affairs, New York Times, Sept. 26, 1992, p. 20.
32 I Who Goes There: Friend or Foe?

Figure 3-l—Casualties and Antifratricide

Measures

~\otallosses..

I

\ Increasing losses

\ from enemy fire > /

\

Decllnmg losses /

8

‘,< from fratricide /

g

a \

/

3

\ /

(u

u ‘ \

/

3 .

/

F

/

‘A

s p.——’”

-. \- .— - -

I

No antifratricide Too stringent antimeasure fratricide measures

>

More stringent antifratricide measures

SOURCE: Office of Technology Assessment, 1993.

alty. The destruction of morale, esprit, and

military cohesion from a fratricide is far greater

than that from a similar loss inflicted by an

enemy. If fratricide’s importance is measured

simply by its effect on the outcomes of battles or

wars, it seems of little significance: the historical

review found no cases in which a fratricidal error

clearly reversed the outcome of a battle. But

incidents of fratricide can cause soldiers to

become too cautious, too timid, and too conservative. These psychological effects may be intangible but every experience of combat shows how

very real they are. In the end, military effectiveness is reduced. Thus, some military analysts

believe that the secondary, hidden effects of

fratricide on the psychology of the surviving

troops may be greater than the direct effects of

losses of forces.

THE ATTACK SEQUENCE

The review of fratricide incidents shows that

very few result exclusively from mechanical

malfunction; in almost all cases, fratricide results

from deliberate-but mistaken-human decisions

and actions that cause casualties among friendly

forces.

The final decision to attack a target is the last

step in a multistep process. If, at any stage of this

process, the shooter could get information showing that his weapon is directed at friendly forces,

then fratricide might be reduced.8

Attacking a target begins with the detection of

something. That ‘‘something’ might be an intuition, a slight movement among the trees, a blip on

a radar scope or other sensor, or even incoming

free.

The next step is classification. The process of

classification can itself contain several steps. At

the moment of first detection, the observer is

typically uncertain whether the small blob seen

through the thermal sight is an enemy tank or a

large warm rock. Is the object a rock or a vehicle?

If a vehicle, is it wheeled or tracked? If tracked,

is it a tank or armored personnel carrier? If a tank,

is it foreign- or U.S.-built? And if U.S. forces are

fighting alongside allies, can the foreign-built

tank be identified as an allied or enemy foreignbuilt tank?9

8 This discussion is based largely on the Defense Advanced Research Projects Agency briefing by Lt. Col. Joseph H. Beno, “Battlefield

IFF” (undated).

g Readers familiar with the intelligence and photointerpretation process should note that this sequence of identilcation is different from

that used by photointerpreters of recomaisaince images. They assume that all the vehicles parked in the interior of an enemy country are enemy

vehicles. First, they want to know whether the spot on the photograph is a vehicle, if so is it a tracked vehicle, if so is it an armored persomel

carrier or a @ and finally, what type of tank and what are its capabilities. IFP can be in some ways a much harder problem. Combat

identification is less concerned with the problem of whether a vehicle is a truck or a tank but in the potentially very hard problem of whether

the truck is U.S. or enemy.
Chapter 3–Avoiding Fratricide: General Considerations I 33

Once a target is identified as enemy, a decision

to attack must be made. This decision is not

automatic. For example, an air-defense missile

unit may clearly identify an aircraft as hostile, but

the aircraft may also be beyond the range of the

units missiles. An infantryman may see a enemy

tank but be armed with a shoulder-launched

rocket that is effective against armored personnel

carriers but not against tanks; a tank gunner may

see several enemy targets and decide to ignore

distant ones because those closer are more threatening.

Finally, after a decision to attack has been

made, the attack must be carried out. Weapons

must be aimed properly and ordnance delivered

where it is intended and not elsewhere, With

modern weapons, ordnance almost always goes

whither the weapon is aimed; in the overwhelming majority of cases, fratricide occurs when the

weapon is aimed at the wrong place.

Separating the attack sequence—which may

only take a few seconds—into these individual

steps may seem a more complex description than

needed. But most fratricide are errors that could

have been avoided if proper information had been

available at any one of these steps. Thus, when

fratricide is the result of a chain of errors, it could

be avoided if the chain is broken at any link.

Breaking a link in the chain requires that the

shooter be given correct information about a

falsely identified target.

THE COMBATANT’S SOURCES OF

IDENTIFICATION INFORMATION

Three overlapping types of information affect

each step of the decision to fire or not to fire on

a potential target. The first and highest level of

information is an overall, general knowledge of

the tactical environment during the battle: where

friendly units are-or at least supposed to be—

and where enemy units are thought to be, plus the

plan of action for the battle. The Army calls this

knowledge ‘‘situational awareness," an awkward

but useful term; other Services include it under

“battle management.”

High-level, general knowledge is not adequate

alone; people involved in the battle must also

have specific information about whether any

particular weapon or vehicle is friendly or enemy.

This information is usually called the Identification of Friend and Foe, or IFF. The military calls

the synthesis of these two types of information

“Combat Identification, ” or CID.

Connecting these first two sets of information

is another type of a priori information brought

along to the battle: doctrine and rules of engagement. These rules tell those engaged in the battle

how to treat information from other sources. In

particular, rules of engagement contain assumptions about how to make decisions with imperfect

knowledge; specifically, is an ambiguous target

assumed friendly until proven hostile, or assumed

hostile until proven friendly? Different forces

under different circumstances will use different

assumptions.

Because destroying a target is a multistep

process and fratricide can be avoided by properly

intervening at any step, more than one approach

can be used to prevent fratricide. This must be

kept in mind when comparing claims about the

efficacy of various approaches. Those proposing

solutions that improve knowledge of the tactical

environment might claim that, say, 75 percent of

fratricide could be avoided by improving situational awareness. While those proposing IFF

solutions might also claim that 75 percent of

fratricide could be avoided by improving IFF.

Clearly, both systems will not eliminate 150

percent of a problem, but both claims might be

true because either approach could reduce fratricide. One study using computer simulation of

land combat illustrates this point in an interesting

way: fratricide was eliminated entirely if forces

were assumed to have either perfect tactical

knowledge-provided by hypothetical perfect

communications and navigation equipment--or

if they were assumed to have perfect IFF—
34 I Who Goes There: Friend or Foe?

provided by hypothetical perfect sensors or IFF

transponders. 10

1 Knowledge of the Tactical Environment

A sense of the tactical situation on the battlefield is so important to avoiding fratricide that it

is sometimes taken for granted. A tank commander in a rear assembly area is surrounded by

other potentially lethal tanks but does not even

think of firing on them because of the firm

knowledge that they are all friendly. This is a case

of almost subconscious tactical awareness.

As the likelihood of encountering hostile forces

increases, tactical information provides clues to

make the search for targets more productive and

helps in the classification of targets as friendly or

enemy. Rarely does a ground force expect an

attack from any direction; typically, their knowledge of the battlefield suggests to them the likely

direction from which an enemy might approach.

The tactical environment thus helps to classify

potential targets as most probably friendly or

enemy. For example, a unit approaching from the

rear is first assumed friendly but a unit approaching from enemy-held territory is frost assumed

hostile. Or, if a commander knows that his and all

other friendly units have orders to advance in a

certain direction, then a unit seen moving at right

angles to that axis will be assumed to be most

likely hostile.11

Before these types of presumptions can be

usefully reliable, however, each unit must have

confidence that it, and its neighboring units, are

unlikely to be heading in a wrong direction and

that wherever each unit is and whichever direction it is headed, nearby units can inform each

other. This requires, in turn, reliable navigation

and communication procedures and equipment.

Communication may be through some centralized clearinghouse. Tactical air forces typically

use this approach. It allows the optimal allocation

of resources across the entire theater of operations. Since airplanes travel so far and so fast,

centralized control is almost required to respond

to enemy attacks and to avoid unintended encounters among friendly forces. The disadvantage of a

centralized system is that large quantities of

information must be transmitted up and down the

chain from the controllers to the units in the field.

Communication may also be through local

networks that link nearby forces. Ground units are

more likely to use this approach. It has the

advantage of minimizing the required flow of

information up and down the chain, Problems can

occur, however, since ground units report up

through a chain to some central commander but

also need to communicate across the chain of

command to units that might be remote in the

command network but happen to be geographically close. Armies have long recognized this

problem and have developed special procedures

to ameliorate it. The simplest approach is to make

major command divisions correspond to real

geographic barriers-for example, rivers or mountain ridges—thus minimizing the need for communication across command lines. Failing that,

command lines must be clear and special attention must be given to liaison between adjacent

forward units that report up through different

chains of command.

Navigation, like communication, can be global

or local. The pilot of a long-range aircraft clearly

needs to know where it is in absolute terms, that

is, its latitude and longitude. World War II

experience shows that when artillery fire was

misplaced, the cause often was a forward observer

10 See I$fIT/Lincoln Laboratories briefing by A.B. Gschwendtner, “DARPA Combat Identitlcation Program at IWT/Lincoln Laboratory”

(Aug. 28, 1992). In the extreme, perfect tactical awareness, that is, precise and complete information about the location of all nearby friendly

forces, would provide as one benefit the equivalent of perfect identification of friends and, by the process of eliminatiou foes. Thus, perfect

tactical awareness is equivalent to perfect IF’F.

11 Rec~l tie case described inch. 2 from Operation Desert Storm in which lost U.S. armored personnel carriers were assumed tO k@i

because they were cutting across the general direction of advance.
— .— ———— -. —

Chapter 3—Avoiding Fratricide: General Considerations 35

correctly calling in fire relative to his position but

erroneously reporting his absolute position. In

many if not most cases, however, position relative

to nearby friendly forces is good enough or even

better, Perhaps only the leader of a tank platoon

needs to know his absolute position, while the rest

of the tank commanders are primarily interested

in local terrain features and the tanks’ positions

relative to each other.

1 Rules of Engagement

The criteria for deciding on the nature of a

target and the response to it are called “rules of

engagement. Military commanders, theorists,

historians, and tacticians have long recognized

the chaotic confusion of combat. No battlefield

participant has perfect knowledge, and critical

decisions must be made, sometimes quickly, with

incomplete and occasionally flatly contradictory

information. Of necessity, every combatant enters

a battle with some a priori knowledge in the form

of a set of decision-making rules to use under

these difficult conditions. This a priori knowledge

is learned through training, exercise, and indoctrination. At the tactical level, military doctrine

provides rules or criteria that are used to decide

when to attack, when to defend, and so on.

Fratricide is affected more by some of the rules

used by each individual combatant to determine

whether an unidentified target is hostile or

friendly, Targets are rarely classified by appearance alone but also by location, behavior, and

recent experience. Thus, the combatants’ tactical

environment affects strongly their decisions about

the danger posed by ambiguous targets.

Two kinds of identification errors are possible:

friendly forces or neutrals can be mistakenly

identified as hostile, and hostile forces can be

mistakenly identified as friendly or neutral. Rules

of engagement will also depend on a comparison

of the consequences of each of these mistakes. For

example, interceptor aircraft pilots typically use

different rules of engagement in different tactical

situations because of the differences in the

consequence of each type of mistake. The differences are clearest when comparing point defense

of an extremely valuable target and defense of a

large area.

For example, Navy fighters fly from an aircraft

carrier, which is a single asset of enormous value.

The loss of the carrier implies the potential loss of

all the aircraft and crew on the carrier. Carriers are

heavily defended, but even a single attacker

getting through can do substantial damage, perhaps disabling the carrier for an extended period.

Moreover, the carrier is a‘ ‘point” target, making

the geometry of an attack unusually clear, Thus,

the Navy’s rule of engagement during hostilities

is that an aircraft approaching the carrier must be

able to prove that it is friendly, or at least

nonthreatening, or else it is assumed to be hostile.

Tactical interceptors trying to defend a large

area face a very different situation and respond

with different rules of engagement. For example,

the classic defense of NATO would have involved a large and confusing array of fighters over

the battlefield. Air defenses of NATO were

multilayered. The first ‘ ‘defense” was attack

against enemy air fields. Enemy intruders would

then have to pass through a screening force of

defending interceptor fighters. These aircraft

might be backed up by a band of defenses

composed of surface-to-air missiles (SAMs). Any

intruders that survived could be attacked by

defending fighters specifically left prowling in

rear areas to catch these ‘‘leakers. ’ Finally,

particularly valuable targets would be defended

by their own local air defenses of short-range

missiles or guns, Thus, the battle would include a

confused and dense air traffic, with fighters

coming from many places and heading toward

many targets. Most of the defended combat

assets—for example, Army assembly areas—

would be more dispersed than an aircraft carrier,

so that a successful attack on any one asset would

be far less critical than a similar attack against a

carrier.

The consequences of firing on a friend are as

severe in the case of area defenses as in the case
36 I Who Goes There: Friend or Foe?

of defense of a valuable point target-a friendly

aircraft gets shot down-but the consequences of

passing up an opportunity to shoot at an enemy

are much less severe—if the first layer of defenses

does not get an intruder then the next will, and so

on, until he approaches the target when he finally

must make his intentions clear. Therefore, the rule

of engagement for unknown aircraft during area

defense is different from that used by the Navy

when defending a carrier: area defenders assume

that an unknown aircraft might be friendly unless

some positive evidence is available to show that

it is hostile.

Ground combatants have a slightly different

perspective on the consequences of the two types

of misidentifications. They tend to think of the

problem as a comparison of the consequences of

either shooting or not shooting. The situation

facing a tank commander can provide a specific

example. Historical evidence from World War II,

training exercises, and testing show a substantial

advantage to the tank that shoots frost in tank-ontank engagements. To hesitate is to risk destruction. And the loss is not a vague, difficult-toquantify overall loss of combat capability, but a

loss that spurs the very compelling motivations of

self-preservation: the tank that fails to aim and

fire first will itself be receiving the fire that might

cause the crew’s death. Thus, ground combatants’

rules of engagement frequently are closer to those

appropriate for defense of a valuable point target;

indeed, the shooter is his own ‘‘high-value”

target. A potentially threatening unknown target

is generally assumed hostile unless there is some

evidence that it is friendly.

The danger that a shooter perceives also affects

his incentives to wait or shoot; the greater the

perceived threat, the greater the urgency to shoot

frost and the more likely a shooter is to assume an

ambiguous target is hostile. This dynamic is

represented in figure 3-2. The vertical axis

i represents the shooter’s estimate that the target he

I sees is an enemy. His estimate can range from

I zero at the bottom of the axis, that is, absolute

confidence that the target is a friend, to 100

100”/0

z’ a)

c

al

(n

5

p

g

a

-c

5

%

.-E

6

w

0“/0

DON’T FIRE

Low Perception of danger High

>

SOURCE: Office of the Assistant Secretary of Defense (C31).

percent at the top of the axis, that is, absolute

confidence that the target is an enemy. (Note that

these estimates of classification confidence refer

to the shooter’s perception; these perceptions, in

turn, may or may not be correct.) The horizontal

axis represents the shooter’s motivation to fire

based on his perception of danger and urgency. It

can range from a minimum motivation, represented on the left-hand side, to maximum motivation, on the right-hand side.

The motivation to fire will change due to

several factors, but the most important variable is

the shooter’s estimate of his own danger. The

graph lays out the different regions that result in

decisions to fire or not fire. If the shooter feels

reasonably secure, then he is willing to wait to

make absolutely certain that the target he has

detected is, in fact, an enemy. Thus, the “free”

area of the graph occupies only the upper comer
-.—.— —. —

Chapter 3–Avoiding Fratricide: General Considerations 37

of the left-hand side, where confidence is high.

Toward the right-hand side of the graph, the

shooter’s perception of danger increases and he

becomes increasingly “trigger happy” until finally, at the extreme right-hand side, where he

feels in immediate grave danger, the shooter may

need high confidence that a target is not an enemy

to keep from shooting. That is, ambiguous targets

will be assumed hostile until proven friendly.

The effect of a shooter’s sense of danger on his

identification accuracy has, in turn, an indirect but

interesting effect on the relationship of target

range and identification accuracy. That increased

weapon range makes IFF more difficult is a

commonplace. The development of long-range

weapons, especially guided weapons not requiring any form of forward spotting, has increased

the range of engagement beyond that at which

targets can be identified, thereby inviting mistaken attacks on friendly targets. Some military

analysts have suggested that reliable IFF range be

made a design constraint on weapon range.

12

Some data, for example, from tank combat

training exercises at the National Training Center,

show a clear relationship between range and

likelihood of fratricide. Accidents are less likely

at shorter engagement ranges, with an important

exception: at very short ranges when the rate of

fratricide engagements is again very high.13 This

phenomenon occurs because, all else being equal,

identification becomes easier at shorter ranges—

reducing fratricide-but all else is not equal.

Engagements occur at very short ranges only

under the desperate and chaotic conditions of a

close-in melee. The effect of greater ease of

identification is overwhelmed by the greater

Figure 3-3—Fratricide and Engagement Range

I

/

L-------- -–-–--T----------——–—- ---1

0 500 1,000 1,500 2,000 2,500 3,000

Range (meters)

SOURCE: U.S. Army Training and Doctrine Command.

stress and confusion characteristic of close combat. See figure 3-3.

Similarly, air defense training shows that the

highest frequency of identification errors occurs

among those manning the shortest range weapons. A Vulcan gun crew cannot engage an

approaching jet aircraft until it is virtually on top

of them, thus forcing an ‘‘us-or-them’ approach

to target engagement decisions. Increased weapon

range certainly is not the solution to fratricide, but

neither is its effect entirely negative: it might

make quick identification more difficult, but it

also can allow more time for decision and

evaluation.

The rules of engagement include other tactical

information. Some is explicit. For example, if a

fighter plane determines from, say, detection of

an enemy radar frequency that an approaching

Iz some ~Wents ~ tie debate about the usefihess of increasing weapon range have gone so f= ~ to suggest ‘it‘i-t@ti ‘iSstie ‘we

ought to be tied to accurate target identification range such that targets at greater ranges are impossible to engage. For example, horn a

congressional report on IFF: “Correcting this imbalance between missile and ID capabilities now requires an accelerated, closely coordinated,

interservice and NATO-wide effort to concentrate resources on achieving the needed identification capability. A concomitant slow-down in

tactical missile acquisition could support that effort. ’ U.S. House of Representatives, Committee on Government Operations, “Identification

of Friend or Foe in Air Warfare-A Capability Imng Neglected and Urgently Needed’ (Washington DC: U.S. Government Printing Office,

Nov. 1, 1985), p. 3. However, an artificially imposed constraint on range persists even when identifkation presents no problem due to, for

example, the clarity of the tactical situation.

13 See “CALL Fraticide Study” (undated), Center for Army hSSOILS Learned (C~), pp. 8-9.
38 I Who Goes There: Friend or Foe?

aircraft is hostile, other aircraft flying in the same

formation are also assumed hostile. (This is

informally called “guilt by association.”) This

assessment is usually accurate, but scenarios in

which a friendly fighter is in hot pursuit of an

enemy are also easy to imagine. Some other

“rules” are implicit and seem to result from

human nature, or can be understood in terms of

the effects of an increased perception of threat—

whether real or not-discussed above. Analysis

of training exercises shows clearly that a gunner’s

recent experience strongly influences his judgments about friend and foe. If, for example, an air

defense unit has just been attacked by “hostile”

aircraft in a training exercise, then the next

airplane that flies over is much more likely to be

judged hostile than it would have been if the

previous overflight had been by friendly aircraft.

Gunners are not, of course, taught to make these

prejudicial assumptions, and this is not an explicit

‘‘rule,’ but few will be surprised by the observation.

IDENTIFICATION: FRIEND OR FOE

‘‘The first requirement in warfare is the ability

to distinguish friend from foe.”14 This statement

from a World War II field manual makes clear the

importance-but not the difficulty--of IFF. Even

the most straightforward technique, looking at a

potential target with human eyes, is neither

simple nor reliable; combatants need training to

identify forces quickly. Even with training, mistakes that appear egregious in the calm of

peaceful retrospection are all too common in the

confusion of combat. The great increase in

weapon range-made possible primarily by developments in weapon guidance systems since

World War II-has in many cases far outstripped

the ability of human observers relying just on

their eyes. IFF today requires additional information from longer range sensors.

Different weapon systems have different requirements for IFF systems. The IFF needed for

short-range and long-range weapons, for example, may have very different reactions times,

abilities to track multiple targets, likelihood of

revealing position, and so on, as well as the

obviously different requirements for range.

~ IFF and the Rules of Engagement

Differences in the rules of engagement will

shift emphasis among technical approaches to

IFF. There is no technical solution that is optimal

for providing positive identification of friend and

foe, where “positive identification” means identification based on positive presence of some

evidence. For example, response to a reliable IFF

interrogation system is positive evidence that the

target is a friend, but lack of response is not

positive evidence that it is an enemy.

In defense of critical point targets, aircraft

carriers being the premier example, defenders

must assume that ambiguous targets are potentially hostile until proven friendly. Thus, the

emphasis is on systems that can prove a target

friendly, such as cooperative question-andanswer systems. The rules of engagement for area

defense will give relatively greater emphasis to

positive identification of foes, hence, noncooperative foe identifiers will be relatively more

important with question-and-answer systems providing frost-order sorting of targets into friends

and unknowns.

Ground forces, when under extreme pressure to

fire quickly, also find themselves in a situation

where ambiguous targets must be assumed hostile

until proven friendly. Thus, ground forces will

concentrate on developing question-and-answer

friend identifiers. (In addition, active IFF by

ground forces is in a primitive state compared to

that of air forces and question-and-answer systems, being easier to implement than noncooperative systems, are a good place to start.)

14 Recognition Picton’ai Manual, War Department Field Wutd 30-30 (June 1943), P. 1.
Chapter 3-Avoiding Fratricide: General Considerations I 39

Figure 3-4--Sources of Information for Identification

/\

Direct ,,/” “\ Indirect

“\,, ,/ /

‘ \

7

I

Passive,, , Active

}

OBSERVER

‘ \

/ ‘.

/, ~., J

9 *

passive ‘ , Active ,/’ ‘\,

,/ ‘ % Passwe ,’ “1 Active

/“ / \

// /

,, ‘,

I I

● )) TARGET

/’ \\

Cooperative ,’” ‘.\ Noncooperative

/ \

/’ ‘\‘\

SOURCE: Office of the Assistant Secretary of Defense (C31).

I Sources of IFF Information

Successful IFF requires that the shooter have

information--carried by some form of energy—

from the putative target. The sources of this

energy and how it is collected can provide a

general, overall classification of the various

technical approaches to IFF. Figure 3-4 shows the

possible combinations of energy and information

sources. The first branch is between direct and

indirect collection. A ‘‘direct’ system is one in

which the shooter collects the information about

a target, while in an ‘indirect’ system some other

observer collects the information and passes it on

to the shooter. An artillery forward observer is a

good example of indirect IFF. The forward

observer, or spotter, uses whatever technique he

has to determine whether a target is friend or foe

and then radios that information back to the

artillery, which accepts it as accurate without any

ability to confirm the information. The rest of the

direct and indirect branches are identical to each

other, so only the direct branch is shown in the

figure.

The observers may be passive or active.

Passive observers do not transmit any energy

themselves but only collect energy normally

transmitted or reflected from the target. An active

observer transmits energy at the target to somehow affect the target in a way that can be

observed.

The target as well may be either passive or

active. A passive target only reflects energy from

its environment. This energy may be natural, like

sunlight, which a passive observer can detect or,

in the case of an active observer, the energy might

be artificially produced specifically to be directed

to and reflected back from the target, as is the

case, for example, with a radar beam. An active

target transmits its own energy, for example,

radio signals or sound.

Thus four possible observer/target energy transmission routes are available: passive/passive,

passive/active, active/passive, and active/active

shown in figure 3-5. An example of the first case

is the simplest IFF system imaginable: a passive

observer identifying a passive target by sensing

reflected sunlight. Or, a passive observer might

also sense energy that is actively transmitted by

the target. This could be radio transmissions in a

foreign language, or radio or radar transmissions
.-

40 I Who Goes There: Friend or Foe?

Box 3-A-The Electromagnetic Spectrum

Chapter 3 discusses in general terms-and the next two chapters discuss in much more specific detail--some

oft he identification and communication techniques important for avoiding friendly fire. Many of these techniques

depend on detecting some form of electromagnetic radiation. The figure 3-A represents the electromagnetic

spectrum. Visible light is the most familiar part of the spectrum but radiation at higher and lower wavelengths is

exactly the same physical phenomenon, just not detectable by the human eye.

Radiation of different wavelengths interacts with matter in different ways, which has two important

consequences: first, the wavelength determines how easily the radiation passes through the atmosphere,

including obscurants, such as fog, smoke, rain, or dust; second, the wavelength affects how the radiation is

generated and detected. In general, radiation is little disturbed by particles smaller than the radiation’s wavelength,

thus longer wavelengths tend to pass more easily through airborne particulate like smoke or fog. Infrared

radiation--with a longer wavelength than visible radiation--can be used to see through clouds of obscurants that

appear impenetrable to the human eye and even longer wavelength radar waves can pass through rain that would

stop infrared radiation.

at a characteristic frequency not used by friendly

forces, or the sound of a tank that is different from

that of friendly tanks.

The observer could be active and transmit

energy to the target. Most commonly this is in the

form of radio signals of some sort. Even if the

target is passive, the shooter can still bounce radar

signals off it—this is standard radar. Thus an

active shooter can detect the radar return of a

passive target and get some information about the

Figure 3-5—Examples of Approaches to IFF

TARGET

Passive Active

Visual ID of Beacons:

weapons type, e.g., Budd-lights,

painted insignia DA RPA-lights

QuestionRadar and-answer

systems

L

SOURCE: DoD and OTA.

target that might allow it to be classified as friend

or foe.

Alternately, the target might actively transmit

energy in response to the shooter’s transmission.

In such a system, the shooter sends a special

signal to the target. If the target wishes to be

identified, and is equipped with the proper

transponders, then it sends back a signal signifying that it is a friend. This is the principle of

‘‘cooperative’ IFF systems, such as the MARK

XII. These are often called ‘‘question-andanswer” systems.

Finally, each branch of the tree shown in the

figure can be cooperative or noncooperative.

Painting special insignia on a vehicle for others to

see is an example of a passive/passive cooperative

system. Normal radar is an active/passive noncooperative system, but if the target adds special

radar reflectors to enhance radar echoes, it becomes an active/passive cooperative system. Just

because a target gives an active response to an

active observer does not imply necessarily that

the target is cooperative; it might be tricked into

responding. Military electronics experts are always trying to find ways to cause an enemy to

transmit energy revealing his position, intentions,

or capability.
Chapter 3—Avoiding Fratricide: Genera Considerations 141

Longer wavelength radiation may be able easily to penetrate the atmosphere but another problem arises as

longer wavelength radiation is used: the ultimate resolution of any imagining device is limited by the ratio of the

wavelength and the size of the imaging optics. Radars using radiation with waves several centimeters or meters

long may easily penetrate long distances, but to achieve any resolution requires proportionally large antennas.

Thus, long wavelength radiation may be useful for communication and detection but is not much use for deriving

an image.

Several parts of the spectrum are of importance to the problem of avoiding fratricide. Communication usually

uses UHF and VHF radio bands. The radar bands shown are used to detect objects and perhaps identify them,

The infrared bands are important because ground forces use them for seeing at night and under conditions of

limited visibility. With increasing wavelength, infrared blends into the millimeter wave bands that will be used by

the proposed question-and-answer identification system for ground combat vehicles.

The Electromagnetic Spectrum

Frequency (Hz) 1072 1 o?~ 1 ().8 1 o’~ 1014 1 o’? 1 o’~ 1 Oa 1 OF 10’ lo~ 1

Wavelength (m) 10 ‘3 10 “ 109 10’ 105

0.4 0.9 1.1 8 10 12

I

Visible Iight ‘

103 0.1 10 103 1 o’ 1 o~

Nominal frequency ruu~cpprpy

-CDbm

range (GHz) Li.3~r’d

O-J03

Wave lengths (microns)

I I I {

Sensitive range of IR lmaglng/targeting

night vision goggles viewer
42 I Who Goes There: Friend or Foe?

I Advantages and Disadvantages

of Each Approach

Each approach to IFF has comparative

strengths and weaknesses. The military prefers, at

least as an ideal, systems that allow the shooter to

remain completely passive because these pose

least risk of revealing information about the

shooter. But passive systems must exploit subtle

difference in emissions, that is, the “signature,”

of a vehicle. Keep in mind that the objective is not

to detect a tank but to distinguish one type of tank

from another against a very complex battlefield

background, and in spite of possible efforts by the

enemy to hide or alter their weapons’ appearance.

Thus, purely passive systems may require sensitive

hence expensive—sensors. Most IFF experts

interviewed by OTA felt that no single passive

sensor would be adequate but that the fused

information from several may have future application.

Active IFF systems—the most obvious examples are radars and question-and-answer systems—

can have longer range but they, of course, might

be detected, providing the enemy information

about friendly forces. This risk can be minimized

by transmitting the least power necessary, transmitting intermittently, using and looking for 1

special transmission patterns (or “waveforms’

known only to other friendly forces, and so on.

In general, cooperative systems are cheaper per

platform and have longer range; it is always easier

to get information out of a target if it wants that

information to get out. Cooperative systems have

the cost disadvantage, however, of becoming

useful only when virtually all of the platforms

within a theater of action are equipped, making

partial deployments unattractive.

Clearly, cooperative systems are really just

friend identifiers, they do not positively identify

enemy. If no reply is received, the shooter might

assume that the target is enemy but perhaps it is

a neutral or a friend without an operating transponder. The final classification in these cases will

depend on the rules of engagement.

Noncooperative systems can, under some circumstances, positively identify enemy. For example, classification could be based on type of

weapon. This approach was easy and reliable

during the long NATO-Warsaw Pact confrontation; NATO forces had NATO weapons and

Warsaw Pact forces had Warsaw Pact weapons.

Thus, the type of weapon identified it as friend or

foe. This approach can, with luck, still work but

in general the world is much more complex today.

For example, in the Persian Gulf War, Syrian

allies were armed with the same Soviet tanks as

the Iraqi enemy while the Iraqis also had the same

French-made aircraft as the French allies. This

profusion of weapon types does not make noncooperative IFF impossible, only more subtle and

difficult. A weapon is much more than the shape

of an outside shell; for example, the same type of

aircraft in two different air forces may use

different engines, have different weapons mounted,

and have different radio or radar frequencies.

Noncooperative IFF may even try to exploit the

habitual tactical behavior of the enemy.

Under some circumstances noncooperative systems may have a cost advantage even when costs

per platforms are higher since the anti-fratricide

benefit is roughly proportioned to the extent of

deployment in contrast to cooperative systems,

which have little benefit until deployment is

virtually complete within a combat group.

Differences in rules of engagement push toward different technical solutions to IFF. As was

discussed before, area defense rules of engagement really require an enemy identifier since,

without some positive evidence that a target is

enemy, it will not be engaged. Thus, in the

extreme, with no way to identify enemy, they

would not shoot at anything. A cooperative

question-and-answer IFF system identifies

friends, but that provides little additional help to

the interceptor pilot: he starts off assuming that

the unknown target is potentially a friend. The

pilot needs some system that can identify an

enemy as an enemy; thus, the need for noncooperative IFF system.
Chapter 3–Avoiding Fratricide: General Considerations 43

In contrast, a Navy pilot returning to a carrier

has to convince the carrier’s defenders that he is

a friend. Anything that identifies enemies does

not give much additional useful information

because the defenders start off assuming that

unknowns are enemy. Thus, the Navy needs a

fail-safe friend identifier and concentrates its

attention on cooperative question-and-answer IFF

systems.

I Information Security

A potential danger with any question-andanswer system is that the enemy might exploit it.

Of course, the occasional transmission of a query

might reveal the shooter’s position, but two even

graver failures are possible. First, if an enemy

could receive the query and then respond with the

proper answer to make himself appear to be a

friend, he could then penetrate defenses easily and

cause great damage. Second, if an enemy could

produce the proper query, he could fool friendly

forces into responding, revealing both their positions and their identity.

Securely encrypting the query and the answer

15 An enemy trying to eliminates both dangers.

exploit a question and answer IFF system could

transmit queries to try to have U.S. weapons

identify themselves, but if an encrypted message,

which only U.S. or allied forces knew, were used

as the query then friendly forces would simply not

respond to any queries that were not properly

encrypted. But what if the enemy could not create

a valid query of his own but at least could

recognize that it was a query? The enemy could

respond with an answering signal to make himself

appear to be a friend. This is called ‘‘spoofing,

Again, if replies were encrypted and only friendly

forces knew the encryption technique, then the

enemy might try to reply with some signal but it

clearly would be counterfeit.

To be genuinely secure, an encrypted message

must be sufficiently complex to foil enemy efforts

to figure out a way to create a valid query and

reply. Additionally, even without understanding

the encryption method, an enemy could simply

record valid queries and then retransmit them.

Therefore, the encrypted form of the query must

be changed frequently. The combination of these

two requirements creates a burden of generating—

and distributing to forces in the field-encryption

keys and other materials. Transport and dissemination of these materials is further complicated

because they must be protected during distribution; if the encryption keys fell into enemy hands,

then the IFF system would be compromised until

new keys could be created and distributed.16

Some front-line forces in Europe, such as Army

air defense units, claim that handling of the

classified IFF encryption keys is so onerous that

proper training with IFF systems is stifled.17

New technical developments allow easier handling and dissemination of secure information

like cipher keys. Systems are under development,

called electronic key management systems, that

would allow the electronic dissemination of

partial keys to regional distribution centers, and

thither to a “Local Management Device” containing a “Key Processer. ’ At the local level a

“Data Transfer Device” is used to carry the key

to the individual weapon. The partial keys alone

would not allow any enemy to decrypt messages

or IFF queries and answers. Instead they would

15 me words t ‘code” ad “cipher” ~d, sifil~ly “CnCOde’ ad ‘ ‘encrypt” are often used interchangeably h the nOnteC~Ca.1 literature.

Experts, however, make a very clear distinction. Code is any set of symbols that represents something else and mayor may not be secret. Thus,

“20500” is the ZIP code for the White House, but anyone that calls can get the code. If a message is encrypted, then anyone who knows the

cypher can read the code but no one else. Sec Nationat Security Agency briefiig, ‘‘Cryptography and Security for Combat ID Systems, ” May

6, 1992, p. 5.

IS See Nation~ Security Agency briefing, ‘‘The Electronic Key Management System (EKMS)” (undated), pp. 34.

17 Monti Callero, “Combat Identification and Fratricide Analysis, ” a briefing presented at the Modeling and Simulation Work.rhop on

Combaf Idennjicafion sponsored by the Defense Advanced Research Projects Agency (D#@PA), Nov. 4, 1992. In fact the keys we only

classified ‘‘cotildential; part of the problem may be more the users’ perception and lack of motivation,
.. —- ——

44 I Who Goes There: Friend or Foe?

provide an input to a computer that would

generate the actual keys. Thus, the partial keys

could be transmitted over the open airwaves for

all to hear. The local computers could load the

actual keys directly into the IFF question-andanswer transmitters so there would be no need to

have the keys written on easy-to-steal paper and

no person-or potential spy—would even need to

know what the key was.

Advocates of noncooperative IFF systems are

ready to point out the burden of handling encryption keys, but noncooperative systems have their

own data-handling challenges. Noncooperative

systems, especially ones that rely on a passive

target, must have available stores of information

on each weapon that might be encountered.

Identifying aircraft from their radar return, for

example, would require detailed information

about the radar returns from dozens of aircraft,

each with several different configurations or

weapon loads, from all possible perspectives.

This information might take the form of databases

in which the characteristics of enemy aircraft

would either be looked up or calculated quickly

from models, but whatever approach is used the

data required could be substantial.

Moreover, these data need to be protected just

as much as encryption keys. Not every detail of a

weapon’s signature will be used for identification

and loss of the data would help an enemy discover

which particular attributes were being used.

Updating data or adjusting for compromised

information during combat could pose severe data

distribution problems. Thus, using a noncooperative approach to IFF will alter but not remove the

requirements for data security and handling.

Compiling the databases required for noncooperative IFF raises delicate diplomatic and intelligence questions. Would allies be willing to

provide sufficient data on their weapons? (Would

the United States be willing to provide comparable data to allies?) If not, would surreptitious

attempts to collect data cause international friction? Would the very existence of data collected

surreptitiously need to be kept secret from allies?

How would information on enemy weapons be

collected? If weapons data are available, could

they be shared with allies during joint operations

without revealing intelligence methods?

Whether using cooperative or noncooperative

IFF systems, operations with allies pose special

problems. In the new global strategic and political

environment, the United States will almost always be engaged militarily with allies at its side,

for political if not military reasons. Moreover,

unlike the relatively stable allied relations in

NATO, future alliances are more likely to be ad

hoc, with even former-and perhaps future--

unfriendly nations acting as temporary allied

partners. The Persian Gulf War, which included

the participation of Syrian forces, provides a

perfect example.

Clearly, it is in the interest of the United States

to help allies not to commit fratricidal attacks on

themselves or on U.S. forces. But the need for

both protection of identification techniques and

allied cooperation creates dilemmas.

For example, encryption keys needed for questionand-answer IFF systems would have to be shared

with allies. But today’s allies might be hostile

tomorrow. At the very least, the United States

must be able to make any system secure again by

changing the encryption keys. Thus, a temporary

ally would not have irrevocable ability to trigger

IFF systems on U.S. weapons.

Encryption keys that fell into the hands of other

nations can be changed quickly-and thus rendered useless—but the same is not true for

hardware and technology. Cooperative question-andanswer systems require that allies have compatible equipment. Presumably the United States

would have to provide the equipment or at least

explain the encryption systems in enough detail

that other nations could produce their own

comparable systems. Yet the United States has

invested significant resources to develop reliable

and secure encryption systems because expert

opinion holds that the resulting capabilities offer

profound tactical and strategic advantages. Even

though keys are changed, if the equipment is left
Chapter 3–Avoiding Fratricide: General Considerations 45

behind, other nations can generate their own keys

and use the equipment for their own IFF with all

of the tactical advantages that accrue.18

The United States must decide whether the

benefits of having a unique technical advantage in

IFF outweigh the benefits of allied interoperability. Without exchange of IFF technology, geographic areas of responsibility would have to be

clearly divided among allies, with each responsible for fratricide avoidance within its area and

special procedures used to reduce accidents at the

boundaries between areas. This problem becomes

particularly important in ad hoc coalitions; the

United States may be willing to share technology

with NATO allies that it is unwilling to share with

temporary allies. The ideal solution might be a

technically less sophisticated, or ‘stripped down,’

IFF system that could be shared with some allies

and was compatible with, but not have all the

advantages of, the complete system.

MAKING CHOICES ABOUT HOW TO

AVOID FRATRICIDE

B Criteria for Judging Antifratricide

Technology

Any successful antifratricide system must meet

several criteria. First, and probably of greatest

importance to the combatants in the field, is that

using the system must not significantly increase

the users’ danger. For example, transmitting an

IFF query in a question-and-answer system must

not give the enemy a chance to intercept the radio

signal, thereby giving away the shooter’s location. A second, and related criterion, is the

difficulty of using the system. If it is too complex

or time-consuming, then it will not be used at all.

The whole process of using the IFF system must

not take so long that the enemy can shoot first

while friendly forces are still fiddling with knobs.

A third criterion is how widely applicable the

system is. Can it tell the shooter something about

everything on the battlefield from infantrymen to

jet fighters? Or is the system limited to those

platforms that can carry a large and expensive

transponder? A fourth criterion, related to the

third, is the system’s reliability. This is more than

simply a question of how long a piece of

equipment will work without maintenance, but of

how well it will work under a complex—and

ultimately unpredictable--array of battlefield conditions that might include active measures by the

enemy to undermine or exploit the system. For

example, how reliably can a noncooperative IFF

system identify an enemy if the enemy knows

what characteristics are being observed and used

for classification and then tries to alter those very

characteristics? Required reliability also depends

on how an IFF system is used. Human eyes and

common sense avoid most potential fratricide; if

another system is used in addition to current

procedures as one last check, then 90 percent

reliability is adequate, but if used instead of

current procedures, 90 percent reliability would

be disastrous.

The fifth criterion is cost, both total costs and

costs compared to alternative requirements. In

absolute terms, total cost is important because

resources are finite and combat can never be made

safe so decisions must be made about when a

system is “good enough. ” Consideration of

comparative costs is potentially less judgmental

and more analytical. If the objective is to save

lives while maintaining combat effectiveness and

a better IFF system is just one way of doing that,

then within a finite budget every dollar spent on

IFF is a dollar not spent on other things that might

also save lives, Perhaps casualties-including

those from fratricide--could be lowered more

effectively by using the same resources to buy

reactive armor for tanks, or for more training, and

so on. The relative importance of a fratricide

casualty and a hostile casualty-which will

determine the allocation of marginal resources—

18 Natio~ sec~~ Agency bfiefkg, “Smey of Target Identiflcatioq ” Sept. 9, 1992
46 I Who Goes There: Friend or Foe?

is a difficult policy question that will not just be

hard to decide but hard to discuss dispassionately.

1 Comparison of Different Approaches To

Avoiding Fratricide

Awareness of the Tactical Environment v. IFF

The main two broad approaches to preventing

fratricide are increasing tactical awareness and

improving target identification. Either approach

offers benefits, each has areas of particular

importance, and both will need to be pursued in

parallel.

The differences are clearest for ground combat.

In general, as ground units approach the enemy,

knowledge of their tactical environment is most

important to avoiding fratricide. This means that

units have the navigational information needed to

know where they are, know where they are

supposed to go, and not stray across avenues of

advance. Nearby units need to communicate to

avoid confusion along their boundaries.

As the battle is entered, one-on-one identification becomes increasingly important. In the

extreme of a melee, the tactical situation could

become so confused and fluid that no person

could keep up with the changes even if the

technology were available to report them. In this

I situation, IFF would be of greater importance,

(See figure 3-6)

When comparing costs of the two approaches,

the multiple benefits of each must be weighed in

the balance. A reliable point-to-point IFF system

would be valuable for IFF but since identification

range can set the limit of effective engagement

range, it might also allow engagements at longer

range. Any system that improved the knowledge

of the tactical environment would reduce fratricide but also allow better control of maneuver

groups, better coordination of fire and combat

units, faster attacks, more efficient movement

across country, and so on, thereby increasing the

overall combat capability of the force. Thus,

when comparing costs of reducing fratricide, only

the appropriate portion of the cost of each system

Figure 3-6-Changing Relative Importance of

Tactical Information and Identification

IFF

A

~

>.—=

5

1 Tactical information

v

\

Deliberate Melde

attack

SOURCE: Combat ID System Program Office.

should be allocated to the antifratricide requirement.

Training and Simulation

The solution to the problem of fratricide is not

just black boxes; training and combat skill are at

least as important. Of course, the skills needed to

avoid fratricide-alertness, unit coordination, and

discipline-are exactly those needed for any unit

to be effective in combat. However, the Services

realize that the danger of fratricide needs special

attention. The Army recently has begun to carry

out separate after-action analysis of simulated

“fratricides” at the National Training Centers.

This includes a standardized format for an evaluation, called the Fratricide Incident Report, which

allows comparison of cases and analysis of most

common causes. Avoiding potential fratricide

dangers are now an explicit part of battle planning. The Army promulgates this new emphasis

through the Training and Doctrine Command

(TRADOC).

Realistic training can reduce casualties in

combat—including fratricide-but the inherent

danger of training creates a connundrum. One

military analyst has suggested that some of the

problems encountered in the Persian Gulf oc-
Chapter 3–Avoiding Fratricide: General Considerations 47

curred because the military did not train enough

and not realistically enough.19 Intense and realistic training results in better combat performance,

no doubt, but it costs lives itself. For example,

1991 was the Air Force’s safest year on record,

with only ten noncombat deaths due to flying

accidents, In one particularly unfortunate 24-hour

period late in 1992, the Air Force lost four aircraft

and 17 crew in three separate accidents.20 Training for war will never be both perfectly effective

and perfectly safe. Those that suggest more

realistic live-fire training must weigh the possible

reduction in losses in some future war against the

higher annual peacetime losses incurred from the

training.

Simulators are an important component of

modem training. These need to be improved to

better represent real combat identification problems. For example, most ground combat fratricide in the Persian Gulf War occurred at night,

but tank training simulators do a much better job

of reproducing daytime than nighttime conditions—

that is, the world seen though infrared imaging

devices.

On a large scale, simulation becomes combat

modeling and, until recently, almost all computerized combat models simply ignored the possibility of fratricide. In fact, most computer models

proceed as though both sides have perfect tactical

information and fratricide never occurs. Indeed,

no provision is allowed in most computer programs to investigate the effects or causes of

fratricide. This past neglect of the problem is now

being addressed.

Doctrine

Doctrine affects the causes and cures of fratricide. Avoiding fratricide has never been the sole,

or even primary, determinant in doctrinal development and rightly so. As fratricide is becoming

relatively more important as a source of casualties, however, it is receiving increasing emphasis,

especially within the Army. Yet fundamental

tenets are not being examined as closely as they

might. For example, the Army emphasizes a very

aggressive approach to ground combat, arguing

that speed and ‘‘momentum” are key to success

and holding overall casualties low. Yet many

fratricide in the Persian Gulf occurred at night at

ranges where the enemy—because of inadequate

sensors—was unable to shoot back. At least one

civilian analyst has suggested that-with the

shooters in less immediate danger-slower, more

deliberate, attacks could have been carried out to

reduce the risk of fratricide. The Army argues that

doctrine and training are not something that one

can turn on and off like a switch. ‘‘Today, troops,

we will use Doctrine B’ will not work. Perhaps

further development of the “weapons tight/

weapons free’ approach would suffice.

Clearly, the Services must coordinate their

approaches to avoiding fratricide. The interaction

of the ground forces with the air, is one clear

example. Close air support has never been the Air

Force’s primary interest and identification of

ground targets has suffered. This is the time, with

new interest in developing antifratricide technology, for careful coordination.

With the end of the Cold War, some military

analysts are discussing quite radical suggestions

for the reassignment of roles and missions of the

Services. Avoiding fratricide will not be the

primary determinant in these decisions, but it

should be important in several cases, for example,

whether to assign close air support to the Army or

whether to assign ground-based air defense missiles to the Air Force.

19 1‘T~aini~~ ~eed~ to ~~ge, too, ~though o~ soldiers we of tie highest quality, they Stfl do not main redkticdly enOUgh fOI WaT. Thele

is too much emphasis on sa~ery. [emphasis added] As a result, units do not train for integrated combat in a live-fire environment, where artillery,

armed helicopters, close air-support jets, armored vehicles and soldiers replicate the violent and confusing conditions found on the battlefield.

Col. David H. Hackwortht “Lessons of a Lucky War,” Newsweek, vol. 117, No. 10, March 11, 1991, p. 49.

ZO Ayiafion Week and Space Technology, “USAF Loses Four Aircraft, Including B-lB, in 24 Hr., ” Dec. 7, 1992, pp. 24-25.
. . - .-

48

—— —

Who Goes There: Friend or Foe?

CONCLUSION

Fratricide is becoming more visible and may

frequently be a relatively more serious source of

casualties in modem U.S. combat because major

military operations are now sometimes possible

with remarkably few losses, as the Persian Gulf

War demonstrated. Cures for the fratricide problem deserve serious, continuing attention, but

fratricide is not a cause for panic and will not lose

the next war.

Avoiding fratricide takes more than just identifying targets properly. And target identification is

a complex problem that will not be solved by a

“black box.” Much of the information needed to

avoid fratricide is exactly the information needed

to be a coherent combat force.

Future wars will include joint operations among

each of the Services and among the United States

and its allies. Today, the military R&D community is pursuing several antifratricide developments. Existing efforts to coordinate with sister

Services and allies should be vigorously maintained.
Avoiding

Fratricide of

Air and

Sea Targets 4

A

s described in the previous chapter, reducing fratricide

requires more than improving identification. This chapter discusses ways to improve both tactical knowledge

and identification to avoid air fratricide. There are

several technical approaches to better identification; each of

these is described briefly below with a discussion of its

advantages and disadvantages. The chapter ends with a discussion of the interaction of military identification systems with

civilian air traffic control and a brief discussion of avoiding

fratricide of ships.

BATTLE MANAGEMENT

‘‘Battle management’ includes collecting information about

where combat resources are needed, setting priorities, and

allocating resources to needs. The tactical knowledge or

‘‘situational awareness’ provided by battle management is so

integral a part of air combat that its importance to avoiding

fratricide is easily overlooked, Yet the foremost antifratricide

measure is properly coordinating friendly forces.

Any efforts that improve coordination also improve combat

effectiveness—and that typically is their primary justification—

but these same efforts can help reduce fratricide. The Navy and

the Air Force discovered during joint operations in the Persian

Gulf War that air tasking orders (ATOs) were difficult to

transmit between the Services’ strike planners. Air Force and

Navy radios were not always compatible and the ATOs were so

voluminous that transmission was time , consuming. These and

other uncovered communication problems are now being

corrected. The resulting improvement in attack efficiency will

be obvious, but better communication and coordination also

will make fratricide less likely.

~-—-- ------ ..-–.. ~

II

1 --1

49
50 I Who Goes There: Friend or Foe?

At the tactical level, long-range surveillance

can sometimes track an enemy airplane from the

moment of takeoff. If a fighter can be seen taking

off from an enemy airfield, few would argue with

the assumption that it is an enemy airplane. This

capability is partially in hand today with the

AWACS. The limitations of the system are range

and, more importantly, tracking. Once the enemy

airplane gets close to a friendly airplane the radar

may no longer see them as separate targets or the

radar may loose track of the airplane when it flies

behind mountains. Then, when a distinct radar

echo is again detected, the tracking radar cannot

tell whether the aircraft came from an enemy

airfield.

AWACS can hand down information, but

greater benefits accrue with a two-way communication between some central coordinating point

and forward shooters equipped with IFF capabilities. For example, to avoid fratricide, surface-toair missiles are specifically allocated defensive

areas in which friendly aircraft are not to fly. Tests

are currently underway to evaluate the feasibility

of transmitting target identification down to

individual missile batteries so that missiles and

fighters can operate in the same area. But much of

the information handed down from the center

could come from analysis of data collected by the

individual missile batteries in the field.

The ultimate goal for any identification and

command system would be an array of individual

shooters equipped with point-to-point identification of friend and foe (IFF) capabilities, collecting

information and sharing it through some network

so identifications are based on a composite

picture built up from all available information.

With the possible exception of the missile-fighter

coordination, none of the communications improvements currently proposed or underdevelopment are being justified solely-or even primarily—as antifratricide measures, but their contribution to avoiding fratricide could be substantial. If allies can tap into the information-sharing

network, they can still get the benefit of U.S. IFF

information without acquiring the technology.

NONCOOPERATIVE IFF

Chapter 3 discussed how cooperative systems

really only identified friends; noncooperative

techniques are able to identify foes as well.

Noncooperative identification of aircraft varies

from the very simple-visual recognition—to

detection, analysis, and classification based on

extremely subtle differences among target aircraft.

The end of the Cold War will change the

equations governing noncooperative IFF. In those

future Third World conflicts in which the United

States has overwhelming air superiority, positive

identification of enemies-and hence noncooperative IFF--will be important. After all, any

unidentified aircraft picked at random is likely to

be friendly under those conditions, so failure to

respond to an IFF query will probably not be

justification to fire. At the same time, the technical challenge now will be in many ways much

greater than during the clearer confrontation

between NATO and the Warsaw Pact forces,

since both Western and Soviet equipment are now

widely proliferated. Therefore, allies and enemies

might very well be using the same equipment, as

they indeed did during the Persian Gulf War. The

Services agree that no single measurement will be

adequate to identify enemies, rather that a composite picture formed from many sources of

information will be needed to be definitive. Some

are discussed below.

1 Radio-Emission Intercept

Perhaps the simplest noncooperative technique—short of visual identification-is passive

interception of radio and radar transmissions.

Each radio and radar system transmits at characteristic frequencies, with characteristic signal

modulation, and-at least for radars--characteristic pulse shapes and repetition rates. Some

aircraft will transmit radio-frequency energy routinely, while others will at least occasionally

transmit. It is also theoretically possible to induce

enemy aircraft to transmit signals, perhaps by
— —— — . .

Chapter 4–Avoiding Fratricide of Air and Sea Targets 51

sending false communications requiring answers

or by appearing to threaten the aircraft in a way

that forces the enemy pilot to turn on defensive

radars or otherwise communicate with his command and control network.

9 Radar

Careful analysis of radar returns reveals much

more about a target than just its bearing and range.

Soon after the development of radar, operators

noticed that the propellers of aircraft modulate the

frequency of the radar return in a characteristic

way. The modern equivalent is called jet engine

modulation (JEM). The air intakes of jet engines

reflect radar signals very efficiently. Some of the

radar waves entering the inlets are reflected off of

the rapidly rotating compressor or fan blades. The

motion of the blades causes a slight Doppler shift

in the frequency of the reflected waves. These

subtle frequency shifts are readily detectable by

sophisticated radars and are, moreover, characteristic of particular jet engines.

The principal limitation of identification by jet

engine modulation is clear: the technique identifies engines, not aircraft. There are a limited

number of military jet engines available worldwide and very different airplanes can be powered

by the same type of engine, At the same time,

individual aircraft in a particular fleet might have

different engines. For example, some U.S. F-16s

have been fitted with the General Electric F-1 10

engine while others have been fitted with modified Pratt and Whitney F-100 engine originally

used in the F-15.

Jet engine modulation should at the very least

distinguish fighter aircraft from transport aircraft,

These two types of aircraft use very different

types of engines: fighter engines typically have

low bypass ratio engines and therefore have

small, high-speed fans, while transports have high

bypass ratio engines with much larger, slower

fans. This method will not, however, necessarily

distinguish military from civilian transports, For

example, the commercial Boeing 757 and the

military McDonnell Douglas C-17 both use the

Pratt and Whitney F-1 17 turbofan engine.1

In addition, the technique is highly dependent

on a proper geometry between the radar and the

target. This dependence can restrict the technique’s application in a dynamic air engagement.

More detailed information about the airplane

structure itself will be available from highresolution radars (HRR) under development.

Radio or radar waves are just a form of electromagnetic radiation, like light, and travel at the

same speed. Light travels about 300 meters in a

microsecond. A typical radar sends out pulses, or

bursts of radio waves, that are on the order of a

microsecond in duration. This means that the

radar pulses are many meters long. Resolving

features much smaller than the radar pulse length

is difficult; thus conventional radars are good at

detecting objects but not much use for providing

details of objects as small as airplanes. Targets

appear just as blobs on the radar screen. If,

however, a radar had a very compact pulse,

perhaps the individual reflective surfaces of an

aircraft could be resolved, which would allow

identification. Such HRRs are currently in research and development. See figure 4-1.

The challenges facing high-resolution radar

development are substantial. First, of course, is

designing and building a radar that can emit

pulses with duration of only several nanoseconds

(billionths of a second). Proponents of highresolution radar are confident that the technology

is available or can be developed. In addition,

however, are the operational challenges. For

example, each target will have a different echo

pattern depending on the perspective of the

viewing radar. Side views will look nothing like

head-on views and data catalogs must be developed of all potentially hostile aircraft seen from

all possible aspects.

1 Mark Larnbert, cd., Jane’s All the WorZd’s Aircraft (CoulsdoU UK: Jane’s Information Group, 1990), p. 748. The civilian designation

for the engine is “PW2040.’
.— - -- - - - - - - ..- .- . — . .

52 I Who Goes There: Friend or Foe?

I

Figure 4-l—High Resolution Radar

Identification with High-Resolution Radar

A ->

Transmitted radar pulse

<

Reflected radar pulse

n

AL

Transmitted radar pulze

<

Reflected radar pulse

\

Foe

Friend

~~

Reflected pulse

\

m “

IDENTIFICATION

I /

-=

/

Catalog of radar signatures

Office of Technology Assessment, 1993.

Moreover, different aircraft can look similar thinner profile and is therefore more difficult to

from particular directions. For example, from a detect. From certain attitudes, if the range is not

trade journal review of the Soviet Su-27 fighter: known, the forward portion of the Su-27 also

“From a head-on or trailing position, the Su-27 resembles that of the USAF/General Dynamics

resembles the Navy/Grumman F-14, but has a F-16 because of its prominent bubble canopy and
—.——

Chapter 4–Avoiding Fratricide of Air and Sea Targets 153

U.S.-built F-18 from the Australian Air Force flies

below a similar-looking Su-27 from the former Soviet

Union. Superficial resemblances of weapons can make

quick identification difficult and unreliable.

its forward aerodynamic strakes, which blend into

the wing leading edges.”2

The algorithms used to discriminate among

aircraft will not look at every detail but will

extract and concentrate on certain defining characteristics. If an enemy knew which characteristics were used for discrimination, then it could try

to suppress or alter them. Thus, the algorithms

will need to be strictly secret and cannot be shared

with all allies.

~ Surface-to-Air Missiles and

Noncooperative IFF

Difficulties of working out aircraft identification has forced surface-to-air missiles (SAMs)

and air interceptors into different zones of responsibility. Typically, SAMs defend strips of airspace from which all friendly aircraft are excluded; thus, anything entering the zone could be

considered hostile and attacked. These areas are

called Missile Engagement Zones or MEZs.

Undefended corridors through the strips allow

friendly aircraft to pass from one side of the strip

to the other. Since enemy aircraft can track

friendly aircraft and soon discover the locations

of the corridors, the corridors must be moved

frequently. Areas outside the MEZs are left to the

interceptors. SAMs would not routinely engage

any aircraft within these Fighter Engagement

Zones, or FEZs.

The introduction of the Patriot missile changed

the utility of this allocation of responsibility

between interceptors and SAMs. The range of the

Patriot is so great that, at least in the European

theater of operations, there would be little area

that was not accessible to both interceptors and

Patriot. The Army, which operates the Patriot

batteries, could severely and artificially restrict

the engagement range of Patriot, but that obviously eliminates much of its capability and the

justification for the cost of the system. To resolve

this conflict, the Army and the Air Force started

a program called Joint Air Defense Operations

(JADO) to test a concept known as Joint Engagement Zones, or JEZs. The test of the feasibility of

An infantryman prepares to launch a hand-held

surface-to-air missile against an attacking aircraft.

The combined-arms battlefield is complex and

dynamic, with many different types of weapons able to

engage enemy targets, thereby greatly complicating

and broadening friend and foe identification

requirements.

2 Donald E. Fink, “Sukhoi, Australian Pilots Fly in Joint Maneuvers, ’ Aviation Week and Space Technology, Mar. 5, 1990, pp. 64-67.
. . . . . . . . . . . . .

54 I Who Goes There: Friend or Foe?

Box 4-A—History of Aircraft Identification

From the time aircraft were first used in combat in World War 1, fratricide has been a problem. Early fratricides

motivated the application of national insignia on the wings and fuselages of aircraft and were at least part of the

reason that some pilots-like the famed “Red Baron’ ’resorted to garish color schemes.

Between the World Wars, the military gave some slight attention to the problem of identifying friendly aircraft

beyond visual range, or in aloud or fog. As early as 1928, the British speculated on the possible use of sirens,

whistles, or “singing” wires to create a signal that could be heard even if the aircraft could not be seen. Bomber

command also considered schemes to use special light signals to identify returning aircraft.1

The problem of fratricidal attacks on aircraft and surface ships took its modern and familiar form with the

development of radar. Early radar inventors foresaw immediately that radar-a device that allowed detection of

aircraft and ships at long range, at night, and through clouds--created the difficult problem of identifying the

detected object?

Early radar developers’ first IFF attempts were to alter the radar returns of friendly craft in some characteristic

way. Radar pulses are nothing more than radio waves that, when reflected from an object, create detectable echo

pulses. The apparent size, or radar “cross-section,” of an object determines the intensity of the radio waves

reflected back. The cross-section in turn, depends roughly on the physical size, shape, and orientation of the object

but also on the electrical characteristics of the object. For example, a conducting rod equal in length to half the

radio wavelength will resonate with the radio waves, which causes a particularly strong reflection. If the resonant

reflection could be turned on and off, then the radar return would vary in a way that could be used for identification

purposes.

. ,.

~

.“*

:+ ““’’””’”w m ~

a as .c.~~ *

o

g

-,-+s

c 1’

m ,“

n i’

z

. .

(

<

a

,, ,.

& w

< .

i

. . . .

..- * . “ —..-

,---u ! * -- . . ~ ~-, &“”m&y* =:--~:. ., ..” . *

,y* --- , =*-& * --- :.-— . .

Itim.m -** -“-*

u-a

$+

T e ‘+ -T::IF4

?~

..-

A German aircraft spotter’s field guide used in World War I. From the very first uses of aircraft in

combat, identification has been a challenge.

In 1937, the British mounted a few test aircraft with an antenna wire running the length of the fuselage. A

switch at the center of the antenna was turned on and off in a regular pattern by a cam. Toggling the switch

effectively changed the length of the antenna and hence the degree of resonance and the radar cross-section.

Thus a radar operator would seethe “size’ ’of the target changing in a pattern known to be characteristic of friendly

aircraft. Tests on individual aircraft were very successful but the crude cams would not have worked for groups

1 ~ans. Swords, A T~~n/~/jjjstoryoft~e &@~~j~~s ofF/a&r, Tedrliml Report MEE1 (Dublin, Ireland:

Department of Microelectronics and Electrical Engineering, Trinity College; 1983), p. 99.

2 [ndeed, early radar developers mined the term “[F~’ for “interrogation, Friend or Foe” or, as Some eW[Y

operators referred to it, Wziefriendorfoe?” See Robert Morris Page, 7?)e Odginofl?acfar(Garden City, NY: Anchor

Books, 1962), p. 166.
— — —

Chapter 4–Avoiding Fratricide of Air and Sea Targets I 55

of aircraft: without perfect synchronization, one airplane’s switch might open just as another’s might close creating

an indecipherable jumble and the system was never adopted.

In 1939, the U.S. Navy mounted atop a destroyer a set of half-wavelength rods on a pole. A motor rotated

the pole and the rods along with it. The rotation changed the orientation of the rods, hence their degree of

resonance with a distant radar and thus the strength of the radar echoes. The radar echo from the destroyer

oscillated in an obvious way that identified it as a friend. This technique, while simple, had the same limitations

as the aircraft system and because of its simplicity was easy for an enemy to copy.

The limitations of passive cooperative techniques led radar researches to active radar reply devices, now

called “transponders.” The first transponders operated at the radar’s frequency; whenever the transponder

detected a radar pulse it would transmit its own pulse at the same frequency. The radar would detect this pulse,

interpret it as a powerful radar return, and the target would show up brightly on the radar screen.

The first transponders were the Mark I and Mark II developed in Britain and similar devices developed around

the same time by the U.S. Naval Research Laboratory (NRL). These devices scanned all radar frequencies in use

by friendly forces and retransmitted a pulse at the appropriate frequency whenever a radar was detected. In the

early days of radar, this technique was possible because only two or three radars frequencies were common, but

as more radar frequencies became available, this approach became untenable simply because the transponder

could not handle the range of frequencies.

By 1941, the proliferation of available radar frequencies required that IFF devices go to a single frequency,

independent of the radar’s frequency. Thus, the radar could operate on whatever frequency was most appropriate

and an additional signal, part of the so-called “secondary” radar, would query the target’s identity. The Mark Ill

was the first such device, sending and receiving signals in the 157-187 MHz (that is, megahertz or millions of cycles

per second) frequency band.3 The Mark Ill became the standard IFF device used by the American, British, and

Canadian air forces during World War Il.

The Mark IV, developed at the U.S. Naval Research Laboratory (NRL), was the first IFF system to use

different frequencies for the query and the response--470 MHz and 493.5 MHz-but it never came into

widespread use.4 In 1942, the NRL began development of the Mark V, also called the UNB or “United Nations

Beacon,” which was to operate near 1 GHz (that is, gigahertz, or billion cycles per second). This program was not

completed until after the war but is important because t he f requencies used-1 .03 GHz for queries and 1.09 GHz

for replies-are still used today on both civilian and military transponders.

The next set of refinements appeared in the Mark “X,” which had a dozen query and response channels

available. 5 Mark X originally allowed aircraft to identify themselves as friendly but did not allow different responses

from different friendly aircraft. A capability, known as SIF,6 allowed different responses from different transponders.

This capability, plus an encrypted query and response mode added to the Mark X became the current Mark XII.

(The Mark XII used for civilian purposes without the encryption capability is still frequently referred to, especially

in Europe, as the Mark X-SIF.)

The Mark XII is today used by U.S. aircraft and ships but is not widely used among U.S. allies.

3 The u-s. equivalent of the Mark Ill was ~lled the SCR 595. See Swords, op. cit., footnote 1, p, 102.

Transponders operating on this principle, now in near universal use on aircraft for civilian air traffic control as well

as military IFF, are usually called ‘(semndary surveillance radars.” See Michael C. Stevens, SeconclWy Surwei//ance

Radar (Norwood, MA: Artech House, 1988), p. 7.

4 Much of this and subsequent wartime development of IFF devices was a joint effort of U.S. and British

scientists, called the Combined Research Group and headquartered at the Naval Research Laboratory.

5 The 11)(11 was a pla~+older until a decision could ~ made about whether a new Mark number WaS justif ied

but it became, perhaps inevitably, the Roman numeral 10. Thus, there are no Marks Vl, Vll, VIII, or IX in the

chronology.

6 U.S. sourmsstate fhaffhe acronym stands for “Selective Identification Feature, ” but some British sour~s

state that the “F’ stands for “Facility.”
56 I Who Goes There: Friend or Foe?

this approach is called JADO/JEZ. Tests are now

being carried out at or planned for Nellis and

Eglin Air Force bases. Since the establishment of

the test program, the Navy has become involved,

to enable it to test operationally some noncooperative surface-to-air identification systems, such

as the Shipboard Advanced Radar Target Identification System, or SARTIS. In February 1994,

coordination of Army ground-based SAMs, Air

Force interceptors, and Navy off-shore SAMs

will be tested along the coast of Florida at Eglin

Air Force Base.3

Patriot missiles belong to the Army but during

joint operations their rules of engagement are

typically set by the Air Force. The Air Force

wants positive hostile identification before allowing the missiles to fire. Lacking any intrinsic

capability to do so, Patriot batteries must depend

on higher echelons to provide the information.

During large-scale battles involving many potential targets, the transfer of information from high

echelons down to individual fire control centers

can saturate current data networks, causing delays

in identification data transfer.

Any development of noncooperative IFF must

consider SAMs from the beginning if they are to

contribute to their full potential. For example,

Patriot missiles, while gaining fame for their

interception of Scud missiles in the Persian Gulf

War, were on permanent weapons-hold status

against aircraft targets. There were, therefore, no

ground-to-air fratricides despite numerous violations of Army air defense areas,4 but also, of

course, Patriot played essentially no role in air

defense operations.5

COOPERATIVE QUESTION-AND-ANSWER

IFF SYSTEMS

Cooperative question-and-answer systems have

been central to combat aircraft identification

since World War II; indeed, some discussions of

“IFF” really only treat this one approach. A

description of the Mark XII and now-canceled

Mark XV provides specific information on these

two systems but also offer a convenient framework for presenting general design considerations

for all question and answer IFF systems.

Although the early “Mark” numbers referred

to specific types of hardware, the Marks XII and

XV—and presumably future models—really refer

to protocols. That is, “Mark XII” refers to an

agreed format, or protocol, for sending and

receiving information. This includes the relevant

frequencies, the length of the radio pulses, the

timing between them, the meaning of different

pulses, and so forth. The Mark number does not

specify the hardware configuration required, and

Mark XII equipment has gone from vacuum tubes

to transistors while using the same protocols. Of

course, some hardware must embody the protocols, but any one of several interrogators and

transponders can handle these formats and are,

therefore, ‘‘Mark XII” devices. For example, the

UPX-23 and UPX-27 refer to two specific shipboard Mark XII interrogators while the APX-72

is an example of a Mark XII airborne transponder.

Thus, the following discussion can combine

specific questions related to protocols with general descriptions of hardware.

The current Mark XII sends out a query in the

‘‘L” radar band, at a frequency of 1.03 GHz. The

query is a pair of radio pulses. The time between

the two pulses can be varied and the transponder

will interpret the query differently depending on

the separation time between the pulses. The

immediate predecessor of the Mark XII, the Mark

X, used three different pulse separations, each

referred to as a ‘‘mode. ’ A pulse separation of 3

microseconds is “Mode l,” 5 microseconds is

q Capt. Rocco Erse~ N6X1, brief~ titled: “Introduction: JADO/JEZ, ” (undated).

4 Briefing entitled, ‘‘Combat Identification: TRADOC Briefing,” Lt. Colonel Mike Bro~ U.S. Army Training and Doctrine Command

(March 12, 1992).

5 U.S. Congress, General Accounting Office, Aircrajl Identification System(U), GAO/C-NSIAD-92-13, p. 13.
Chapter 4–Avoiding Fratricide of Air and Sea Targets! 57

“Mode 2,” and 8 microseconds is “Mode 3.’

These modes are still in use today.

The reply signal from the Mark X contained at

least a pair of 1.09 GHz “framing" pulses 20.3

microseconds apart. These pulses indicate when

the reply message starts and stops. Between the

framing pulses of the response from the original

Mark X lay six time slots 2.9 microseconds wide,

each of which may or may not contain a radio

pulse.6 A pulse in a particular time slot represents

a “1“ and lack of a pulse represents a “O,’ thus

allowing transmission of binary numerical data.

The improvements implemented for the Selective

Identification Feature, or SIF (see box 4-A), and

Mark XII included an increase to twelve slots

between the framing pulses to allow for 4,096

possible replies. With the available number of

possible replies, airborne transponders can give a

distinct reply that identifies not just whether the

aircraft is a friend but which aircraft it is-exactly

as in civilian air traffic control today.

A simple transponder can be exploited easily

by the enemy. If the enemy could get the

transponder to respond to a query, friendly

aircraft would reveal their positions and identities. To avoid this weakness, a program to

develop an encrypted query mode was started in

1954. Mark XII IFF devices have this encrypted

question-and-answer mode, called Mode 4. The

Mode 4 query starts with four time synchronization pulses followed by up to 32 pulses that

contain encrypted information telling the receiving transponder that the query is a valid, friendly

query. Invalid queries are simply ignored by the

transponder. The response to a Mode 4 query is a

string of three pulses. The reply can start after any

of 16 possible time delays; thus by changing the

delay the reply can convey limited information.

See box 4-B for the specifications of the interrogations and replies.

The IFF interrogators and transponders cannot

work by themselves. If the transponder sent out a

query in all directions and got a response back, the

IFF interrogator would only know that there is

somewhere out there at least one friendly aircraft.

To query particular aircraft, interrogator antennas

are mounted along with conventional radar antennas to point in a particular direction. When a

target is detected by the radar, the IFF interrogator

can send out a query in the same direction as the

radar beam asking the aircraft to identify itself.

The information from the reply can then be

displayed on the radar screen directly.

The transponder can be simpler than the

interrogator. When it receives a query, the answer

need not be directed to the questioning radar;

instead a simple omni-directional antenna is

adequate and the interrogating radar can determine which aircraft is responding by correlating

the response with the radar beam’s direction.

Because of the difference in complexity, interrogators are generally more expensive than transponders. This affects the extent of their use; for

example, some aircraft are fitted only with

transponders. Ships and control aircraft like the

E-2 are routinely fitted with the more expensive

interrogators, but many interceptors are not.

The different modes can be used for military air

traffic control. For example, an aircraft carrier’s

radar will show all the aircraft in its vicinity but this

may be over a hundred aircraft in some crowded air

corridors, such as over the Mediterranean.7 The

radar operator can use IFF modes to highlight

friendly military aircraft.

b Oral history at the Navat Research Laboratory holds that the time slots were intended to be an even 3.0 microseconds wide but the fust

delivexy of delay lines for the prototype proved faulty, testing at only 2.9 microseconds. Rather than wait for new delay 1ines, researchers

proceeded with what they had available. Thus, it came to pass that framing pulses of 20.3 (that is, 7x2.9) microseconds will be in use well into

the twenty-first century. This tale illustrates how protocol standards should be developed carefully because they tend to stay with us for a long

time.

7 Briefing entitled ‘‘Automatic Identification (AutoID), ” Applied Physics Laboratory, The Johns Hopkins University, (undated).
. . . - .- - . -- - . - - - . . . . - - - . . - . - -- — -_ — —- -—_ -_

58 I Who Goes There: Friend or Foe?

Box 4-B-Formats and Protocols for the Mark XII

Mark XII interrogations and replies are pulses of radio waves at 1.03 and 1.09 GHz. Information is conveyed

by changes in the number and timing of the pulses. The interrogation for military Modes 1,2, and 3 and civilian

Modes A, B, C, and D are a pair of pulses separated by a time delay, the length of which is specified by the particular

mode. This format is illustrated in figure A.

Mark XII interrogation format

J L_

F 7 Suppressor

-~ ~ pulse

IL

A< 0.8 p sec

< Delay

Mode 3/A reply format

>< 0.45 p sec

ti 1< 20.3 p sec

Mode 3/A reply pulse 7654

F1 ~ Al A2 C4 A4 B2 B4 D4 F2

JLJ-JL.-LIL---L-l ULll -

Mode 4 formats

Query Reply

JLLIL

Time synchronization

pulse

-...-UJLL JLIL

Up to 32 data

pulses

SOURCE: NATO STANAG 4193 (Part 1) (Edition 2), 1990.
———— —

Chapter 4–Avoiding Fratricide of Air and Sea Targets 159

Box 4-B–Formats and Protocols for the Mark XII

No antenna is perfect, sending signals Table A—IFF Modes

only in the direction wanted and no other. —

Military civil

Energy leakage through “side lobes” could Delay (p see) mode mode Use

cause transponders to f ire even when t he radar 3 1 Military Function ID

is not pointed directly at them. To avoid this 5 2 Military Function ID

problem, some interrogators send out a sup- 8 3 = A Aircraft identification

pressor pulse in every direction except the 17 B Not used internationally

direction the radar is pointed. A transponder 21 c Altitude

25 D Not used internationally

can compare the size of the two signals and if

the suppressor pulse is larger than the framing SOURCE: NATO

pulses, the query is ignored.

Each interrogation mode has a different time separating the pulses, except that military Mode 3 is equivalent

to civilian Mode A. The various Modes are shown in table 4-1. The pulse separation in Mode 1 is so short that not

ail interrogators and transponders can handle the insertion of a suppressor signal in Mode 1.

The reply format consists of a pair of framing pulses 20.3 microseconds apart with up to 12 signal pulses

between them, although not all modes use all the availabie signal pulses for information. The format is shown in

figure B. Numerical values are transmitted in the replies in the form of four-digit “octal” or base eight numbers of

the form ABCD. Each of the these digits is the sum of three pulse values. in the figure, for example, three of the

pulses are Iabeled Al, A2, and A4. The first digit in the four-digit number is A which equals Al +A2+A4 where Al

has a value of one, A2 a value of two, and A4 a value of four if a pulse is present in the appropriate time slot, and

zero otherwise. Thus the decimal number 4,012, which is 7,654 in octal notation, would be represented by

A=7=A4+A2+A1, B=6=B4+B2, C=5=C4+C1, and D=4=D4. The resulting pulse pattern is shown in figure C.

Mode 4 pulses, the encrypted mode, have a different format. The interrogation pulse starts with four time

synchronization pulses. These are followed by up to 32 data pulses. The arrangement of these pulses validates

that the query is indeed from a friendly interrogator and transponders should send a reply. The reply is a set of

three pulse delayed by various amounts. These formats are shown in figure D.

1 Passive Cooperative IFF Measures appropriate noncooperative identification techCooperation by friendly targets could enhance

the discriminating ability of passive friendly

observers using the noncooperative IFF techniques described above. Few of these ideas are

beyond the conceptual stage. They include adding

radar highlights that would stand out on highresolution radar, inducing vibrations that would

show upon Doppler radars,8 and even modulating

or doping exhausts to make them stand out to

infrared sensors. Application of any of these

techniques will require first the deployment of the

nique.

1 Limitations of Mark X11, Improvements in

Mark XV, and Next Generation IFF

This section briefly discusses some of the

current and potential short-comings of the current

Mark XII IFF system. These problems were to be

corrected with the development of the Mark XV.

The Mark XV development was canceled in

December 1990 and the still-to-be-defined successor question-and-answer system is now referred to as the Next Generation IFF, or NGIFF.

g Briefing entitled, ‘ ‘Achieving Covert Communications and Ground-Combat Identification Using Modulated Scatterers, ’ E.K. Miller and

D.M. Mctzger, Mechanical and Electronic Engineering, Lns Alamos National Laboratory (Mar. 11, 1992).
I

I

I

. -. . -. . - -— - — - - - - - -- - -- - - - — - - - - - - - - - — - -

60 I Who Goes There: Friend or Foe?

A typical Mark XII airborne transponder. IFF formats

and protocols can be handled by any of several types

of interrogators and transponders.

As discussed in chapter 3, the three ways in

which an enemy can defeat the purpose of an IFF

system are exploitation, spoofing, and denial. An

enemy exploits an IFF system by getting information from it. For example, if an enemy could

record queries from a Mark XII interrogator and

then rebroadcast them, then he could trigger the

Mark XII transponders and have friendly aircraft

identify themselves and reveal their positions.

Even if recording valid queries were impossible,

an enemy could guess at queries, hoping to hit

upon a valid combination. With thousands of

possible queries this may seem daunting, but in

fact modem electronic devices should allow

transmission of scores of guessed queries per

second.

The Mark XV would have reduced or eliminated the possibility of enemy exploitation by

changing the query codes rapidly. Valid Mark XII

query codes are changed regularly but the process

is cumbersome, involving the use of printed keys

and the mechanical insertion of key values into

the transponder. In the late 1960s, the Navy flight

tested a system called TACIT (Time Authenticated Cryptographic Interrogator/Transponder),

which allowed the rapid, automatic changing of

query codes. Indeed, codes could be changed so

rapidly that an enemy could not record and

retransmit a code before it became obsolete

The Mark XV was to have a capability like

TACIT. This means that all transponders, at least

within a theater of operation and ideally worldwide, would switch codes in an agreed pattern,

say, every second on the second. Clearly the

requirements for time synchronization across

literally thousands of platforms around the world

is a major technical challenge. But modem

developments in electronics makes the task possible if not easy; modem electronic clocks have

accuracies of a fraction of a second per year. The

encryption computer contained with each interrogator would be supplied with a “seed” key that

would allow generation of a query code, then

algorithms embedded in the computer would

generate the next code from that seed and so on

until a new seed were supplied.

An enemy’s ability to appear friendly to an IFF

system is called spoofing. Just as an enemy could

try to exploit the Mark XII by recording or

guessing at proper queries, an enemy could also

try to spoof the Mark XII either by recording or

guessing proper replies. The Mark XV would

have incorporated several improvements to inhibit spoofing. These included a greater possible

number of responses creating a greater barrier to

straightforward guessing. The Mark XV would

have used “spread spectrum” pulses, that is, a

sharp pulse converted by the transmitter electronics into a broad frequency pulse that has lower

peak energy at any given frequency, making

interception more difficult. The receiver has

similar electronics that operate in reverse, compressing the spread pulse into a sharp information

pulse. A receiver that knows the proper spreading

and compressing function gets substantial receiver gain, but an enemy that does not know the

details of the function will have a difficult time

resolving the signal from background noise.9

v Don J. Torrieri, Principles of Secure Communication Systems, Second Edition (Bestow MA: Artech House, 1992), pp. 95-99.
Chapter 4-Avoiding Fratricide of Air and Sea Targets I 61

Also, the strength of the reply signal would have

been adjusted for the distance of the interrogator,

with the reply no stronger than it needed to be thus

making more difficult the interception and retransmission of a valid reply,

An enemy might be able to deny the use of an

IFF system, For example, jamming of the radio

signals is one straightforward approach. Almost

any radio can be j ammed if an enemy is willing to

invest adequate resources and can get jammers in

the right places. Military radio and radar systems

are designed to make j amming more difficult, but

Jamming can never be made impossible and the

amount of effort that is appropriate to invest in

electronic antijamming capability depends sensitively on 1) the presumed combat environment, 2)

a judgment about the value of working in a

Jamming environment, and 3) a comparison with

other approaches to solving the jamming problem

(e.g., blowing up the enemy jammers).

Military users of Mark XII consider it easily

Jammed. Improvements contemplated for the

Mark XV included significant antijamming capability. For example, the query and response pulses

would be much longer than those of the Mark XII.

Longer pulses mean the potential for greater total

energy in the pulse and a longer signal integration

time, which makes j amming more difficult, Each

bit of information in a pulse would be spread over

the whole pulse length, which makes reading the

pulses in the presence of j amming more reliable.

The spread spectrum electronics that contribute

so much to communications security also make

jamming more difficult. Finally, the structure of

the pulses would allow for detection of transmission errors so that if jamming occurred, the

operators would know that information received

was faulty and should be rebroadcast.

Jamming is one potential threat, but an indirect

form of denial is perhaps the most important: if

the operators do not have confidence in the

system, they turn it off. Several experienced pilots

reported to OTA that during the Vietnam War,

they turned off their Mark XII IFF systems as

soon as they entered enemy air space. Other say

that more recently, on missions flown near

potentially hostile forces around the Mediterranean Sea, Mark XII were turned off. The reasons

are the same in both cases: a fear that enemy-or

even friendly--queries would trigger the transponders and thus reveal the aircraft’s presence.

Against the more sophisticated Soviet threat,

pilots expected to turn off IFF transponders long

before they crossed enemy lines. If the operator

believes that an IFF system increases his danger,

then it will not be used to its full potential, if it is

used at all. Thus, the ON/OFF switch becomes

another means of denial. Mark XV improvements

would have mitigated the problem of inadvertent

friendly triggering of the transponder but this is

clearly more than just a technology problem and

a solution requires careful coordination among

the eventual users.

Despite its promised improvements, Mark XV

development was canceled in 1990, both because

of increasing technical complexity and the growing estimated cost of deploying the system. Over

40,000 Mark XII sets have been produced10 and

approximately 25,000 are still in use. With a huge

number of platforms needing IFF devices—and a

need for at least 17,000 Mark XVs was forecast—

acquisition costs multiply rapidly. Indeed, the

cost of the Mark XV would have precluded

outfitting every vehicle with a device, which

raises the distressing question of the value of an

IFF system that is so expensive that it is not

carried by all platforms.

The cancellation of the Mark XV program

leaves the future of cooperative aircraft IFF

uncertain. The original motivation for the program, obsolescence of the Mark XII, still stands,

so some replacement capability is probably needed.

Most studies by the military Services assume that

1° Navy Briefing, “Defense Acquisition Board Milestone ‘O’ Review: Cooperative Friendly Aircraft Identification Presentation for C31

Systems Committee,” July 22, 1992.
62 I Who Goes There: Friend or Foe?

a cooperative IFF system will provide some part

of that needed capability.

Perhaps the most obvious Mark XII replacement is a system with performance that is a

compromise between that of the Mark XII and of

the Mark XV. By backing off on the Mark XV

performance goals, costs could be reduced for any

replacement . Antijamming capability was one of

the major determinants of costs. Justifying any

particular antijamming requirement is difficult

for any piece of electronic equipment. No one can

ever be entirely sure what resources a future

enemy might devote to j amming, how its jammers

might operate, be deployed, and so on. Thus,

making very conservative assumptions is enticing

but has substantial cost consequences for electronic systems. Options for future IFF systems

range from using the current Mark XII protocols

and radio wave forms-that is, making no antij amming improvement to the Mark XII-to

using the spread spectrum waveforms proposed

for the Mark XV. In between are compromise

solutions that include using a modified and

reduced spread spectrum waveform or using

directional antennas to reduce jamming interference. The Germans have made proposals for

moving to a different frequency band altogether,

in the S-band, which covers the range from 2-4

GHz. One advantage of S-band is that the

airwaves are less crowded at those frequencies.

As a general rule, however, the higher the

frequency of radio transmission, the shorter the

range. Thus, an S-band system has shorter range

than an L-band system. The shorter range of

S-band actually has one advantage: it is harder to

jam with a few distant but powerful jammers.

Short range is less of a handicap in the crowded

European theater in which the Germans operate

but it makes S-band unattractive for the worldwide operations needed by the United States.

Maintaining communications security was a

secondary contributor to the cost of the Mark XV.

The Mark XV was to have anew cryptocomputer,

the KI-15, that would have provided very good

security through electronic handling of cipher

keys and rapid, automatic changing of keys that

would have saved operational costs. While the

cryptographic security component of the Mark

XII is quite old, the whole system need not be

junked. For example, according to the National

Security Agency, new cryptocomputers could be

added to the current Mark XIIs or to similar

follow-on models. These would provide better

security without the full cost of the Mark XV’s

capability.

The important point is that the Mark XV

improvements were not all-or-nothing; compromises in performance are possible. DoD could

build a system better than today’s Mark XII but

cheaper than the Mark XV. The performance

goals for the Mark XV were established during

the Cold War. Now that war with Russia seems far

less likely and the more likely opponents are far

less challenging, backing off on the performance

requirements of the Mark XV should be given

serious consideration. The exact emphasis is, of

course, subject to judgment, but technical experts

interviewed by OTA felt that the end of the Soviet

threat has probably reduced the need for antijamming improvements more than the need for

communication security improvements.

COORDINATION WITH CIVILIAN AIR

TRAFFIC CONTROL

B Civilian Airborne Transponders

A mid-air collision on December 16, 1960

between a United DC-8 approaching Idlewild

(now Kennedy) airport and a TWA Super Constellation approaching LaGuardia killed the 128

aircraft occupants and eight others on the ground

and highlighted the limitations of the air traffic

control system even when aircraft were under

positive control.11

11 Ric~d J. Ken~ safe, separated, and Soaring: A History of Civil Aviation Policy, 1961-1972 (Washington DC: U.S. Department of

Transportation, Federal Aviation Administration; 1980), pp. 6-7.
Chapter 4–Avoiding Fratricide of Air and Sea Targets 63

The New York City mid-air collision accelerated adoption of several technical improvements

for civil air traffic control, for example, secondary

radar transponders on civilian aircraft. By 1953,

Mark X frequencies and protocols had been

released for international civilian use.12 The

civilian airliners were given use of Mode 3, which

in civilian use is called Mode A. Civilian airliners

use the 4,096 possible combinations of reply

signal to identify the aircrafts’ flight numbers,

with some numbers reserved for special messages; for example, any aircraft that responds to

a Mode A query with a “flight number’ of octal

code 7700 is saying that it has an emergency.

Additional civilian modes called, not surprisingly, Modes B, C, and D have been added

subsequently, but only Mode C, with a 21-

microsecond delay between query pulses, is

commonly used. Ground-based radars can determine ground coordinates directly but are not able

to determine aircraft altitude. Therefore, most

aircraft now have transponders connected to the

aircraft altimeter allowing the transponder to

report automatically the aircraft’s altitude in

response to a Mode C query, The use by civilians

of military IFF frequencies and protocols has

important implications anywhere the two types of

aircraft expect to share the same airspace.

Mode S

Secondary surveillance radar has become so

useful and important to civilian air traffic control

that it has become a victim of its own success. In

some particularly heavy air corridors-for example, Europe and the east and west coasts of the

United States—aircraft can receive identification

requests from dozens of radars. This may include

air corridor radars and overlapping radar coverage

from closely spaced airports. Moreover, not all

nations’ air traffic control procedures are identical or even particularly well-coordinated, so

neighboring countries may simultaneously query

the same aircraft for information important to

their air traffic control.13

The multitude of interrogators can result in

hundreds of queries each second. This volume can

saturate the airborne transponders, making them

unavailable when essential radar queries come

through. Moreover, all of the aircraft are sending

out identification calls more or less continuously;

interrogators are receiving the replies from properly designated aircraft and a multitude of stray

replies that are picked up as interference.

The ongoing, but gradual, adoption of a new

mode-Mode S, where ‘S’ stands for ‘select"—

is the internationally agreed technical solution to

these problems. In Mode S, interrogating radars

will not routinely send out a general ‘ ‘who’s out

there” query with every sweep. Mode S requires

that each aircraft have a unique, permanent

identifying number. A Mode S interrogator will

occasionally send out an ‘‘all-call’ message to

establish the identities of all of the aircraft within

its coverage. The radar and interrogator can then

send out specific messages to specific aircraft,

requesting altitude, for example. As an airplane

leaves the coverage area of one radar, the

information about that specific airplane can be

sent by land lines to the next radar, which will be

expecting it.14

Proponents of the Mode S system claim that it

will reduce transponder information loads by at

least two-thirds. It will also allow denser air

traffic near airports. One current constraint on

traffic density is the resolution of air traffic radars,

not just safe separation distances. Two closely

spaced aircraft will respond to the same Mode A

or Mode C query and their answers will overlap

when received by the interrogating radar, which

12 Mi~lael c, Stevem, Se~o&~ Sumeillance R~ar @oWood, MA: fi~h House, 1988), p. 9.

13 Lief IClette, “Europe’s Crowded Skies: Managing Civil-Military Airspace, ” International Defense Review, July 1992, pp. 659-662.

14 Radio ~~~~~ Cotission for Aeromutics, “ Minimum Operational Performance Standards for Air Trafilc Control Radar Beacon

System/Mode Select (ATCRBS/Mode S) Airborne Equipment, ” Document Number RTCA/DO-181 (March 1983).
— . . . . . . - -- - - - — . . . . . . . . . -. .- - . . . - — . . .- - .

64 I Who Goes There: Friend or Foe?

I

will not be able to make sense of either of them.15

With Mode S, a radar could interrogate one

airplane and then, a millisecond later, send a

separate interrogation to the second airplane. This

time lag is so short that it will not affect air safety

but will allow electronic separation of the replies.

Thus, while Mode S is not needed by the U.S.

military, it is part of a much-needed world-wide

civilian standardization and modernization effort,

of particular importance in Europe.

Mode S will allow messages longer than the

current Mode A and C 12-bit messages. The

greater number of message bits plus the unique

identification numbers for aircraft allow limited

two-way digital and text data transfer between

aircraft and the ground that would be impossible

with today’s free-for-all interrogation system. For

example, just as Mode C now queries altitude,

Mode S could, in principle, query aircraft speed,

bearing, rate of decent, destination, even fuel

load. These data would be used by air traffic

controllers to better manage aircraft in dense

traffic.

Information can also be sent up to the aircraft.

For example, changes of air traffic radio frequency could be sent automatically when aircraft

move from one control zone to another. Weather

advisories or changes in flight plan instruction

could be sent up, then written or otherwise stored

so they would be available to the pilot at a time of

her choosing.

The basic Mode S is called “Level l;” “Level

2’ includes the ability to receive short commands

of 56 bits; “Level 3“ includes the ability to

receive longer command sets of 112 bits and

transmit short ones; “Level 4“ includes the

ability to receive and transmit long commands.

Since the system is not yet operational, all of the

ultimate uses for the data transmission channels

of Mode S are not clear but enough is known now

to see that they will be useful to civilian pilots, but

less so to military pilots.

Mode S will be adopted in phases in the United

States. Large commercial passenger carriers must

have Mode S transponders operating by the end of

1993. Commuter carriers and general aviation

will acquire Mode S capability more gradually.

Perhaps within 10 years, all aircraft, even general

aviation, will need Mode S if they are to operate

in dense air-traffic areas of the United States.

The military must operate in a world where the

overwhelming majority of airspace is under

civilian control (at least in peace time). This

means that the military must adopt at least some

of the Mode S capability into any future IFF

system. The Services have two major problems

with Mode S, neither of which is insurmountable

but each of which must be handled. First is cost.

The cost to the military of Mode S will be more

than just the cost of the equipment. Another black

box can always get squeezed into a transport, but

every cubic inch on a fighter plane is already

occupied. That means redesigning existing equipment, placing antennas, dealing with waste heat

from more electronics, and so on. Mode S was to

be an integral part of the Mark XV. With its

cancellation, DoD must find some other way to

outfit its aircraft with Mode S or come to some

accommodation with civilian air traffic control.16

The benefits of Mode S are greatest in the

densest air traffic. Service resistance to the cost of

Mode S is easy to understand because dense

traffic areas are just those in which military

aircraft are least likely to fly, at least in the United

States. But since commercial aircraft can hardly

avoid these areas, they will need Mode S. Then,

15 “f’hi~ is due t. he ffite speed of tie radio waves sent out by he &ansponders. Since radio @avels about S(XI meters per microsecond, a

20-microsecond reply is 6,000 meters long and any two aircraft whose distances fkom the interrogator differ by less than that will send messages

that will overlap, or be ‘garbled,’ at the receiver. Note that the aimraft need not be dangerously close; since air tratllc control radars normally

do not discriminate aircraft altitude, two airplanes with substantial vertical separation can still have very close ground tracks.

lb ~~er fmm Barry Mbefl Harris, Deputy AWstrator, Federal Aviation Admum“stratiorL U.S. Department of Transportationi to Richard

G. Howe, Acting ChairmmL Policy Board on Federal Aviation, Office of the Secretary of Defense, Apr. 20, 1990.
Chapter 4–Avoiding Fratricide of Air and Sea Targets 165

when Mode S is widespread, it doubtless will be

used-even if not essential-in the less heavily

traveled airspace where military aircraft do fly.

The FAA does not foresee Mode S message

capability as a requirement for operating in

general U.S. airspace, but requirements will be

imposed on aircraft that wish to operate near the

Nation’s busiest airports. In principle, military

flights could simply avoid those areas. Currently

the DoD foresees that fighters eventually will be

outfitted with Mode S/Level 2 and cargo transports will be outfitted with Mode S/Level 4.17

The second problem is more subtle: the information that Mode S might provide to potential

enemies. This is not a wartime problem—pilots

would just turn civilian modes off in war theaters

and the military would take over air traffic

control. It is, rather, a problem of long-term

peacetime intelligence information loss. Current

Mark X-SIF identifies an airplane by its flight

number for that day. Mode S will identify each

airplane uniquely by its tail number. The Services

will not tolerate this since it would allow a

potential enemy to build up over time a valuable

database. For example, long-term compilation of

aircraft tracks might reveal how often particular

aircraft shuttle between deployment areas and

depot maintenance sites. One solution is to allot

to the Services a block of numbers that they could

mix around at random. Civilian and foreign air

traffic controllers would then know that the

aircraft is a U.S. military aircraft but not which

one,

The military may object to even this much

information being available, but presumably the

United States is also interested in clearly identifying civilian airliners as such. Any system that

loudly proclaims all civilian aircraft inevitably

identifies military aircraft as well, at the very least

by default, since any airplane not proclaiming

loudly will be assumed military. Thus, this

weakness may bean inevitable price that has to be

paid for the protection of civil aircraft from

accidental attack.

fl Other Areas Requiring Civil-Military

Coordination

Today the military and the FAA jointly operate

air traffic control (ATC) systems covering the

United States and the air approaches to it, with the

military providing about a fifth of the ATC assets.

The Nation is in the process of converting to a

unified system, called the ARSA-4, to be operated

solely by the FAA. The unified system should be

more capable and cheaper. The Air Force will

receive data from the FAA radars and interrogators, which will be used for the identification of

aircraft approaching the United States .18 Some of

the current Air Force air traffic control computers

cannot keep up with the high traffic densities in

the Nation’s busiest corridors, but sections of

radar coverage can be systematically blocked out

from the Air Force data link to allow the Air Force

system to concentrate on only those sectors that

are important to it. In the future, all Service ATC

equipment and computers will be comparable

with FAA equipment.

The FAA plans also for the gradual adoption of

an automatic system to help pilots avoid mid-air

collisions. Currently, aircraft pilots have visual

information, on-board radars, and secondary information relayed up from ground radars. Ground

radars can interrogate the transponders carried on

aircraft but currently the aircraft cannot interrogate each other’s transponders. The Traffic Alert

and Collision Avoidance System (TCAS) will

allow aircraft to use Mode-S transponders to get

information from other aircraft in the area which

will allow on-board computers to calculate and

recommend collision avoidance maneuvers. TCAS

will be in place for airlines by the end of 1993.

TCAS may eventually place some requirements

17 Frti COISO~ OSD liaison to FAA, persOnal brief.

1S Tom McNiff, *‘Air Force, FAA Working on New Radar System, ’ JournaZ of Commerce (Sept. 21, 1992), p. B3, (and personal briefings

from Richard Lay, FAA in-route radar manager)
66 I Who Goes There: Friend or Foe?

on military aircraft even if none are in place now.

The first phase of TCAS for general aviation or

commuter carriers is planned for implementation

in 19950

1

9

If cooperative IFF systems are to be used by

allies or even by U.S. forces operating in allied

countries, then frequency allocation problems

must be resolved. For example, the current Mark

XII transponders can cause interference in Germany, where their use comes under some restriction. The converse problem is getting everyone

onto the same frequency. For example, communications between military and civilian aircraft are

not always easy since military fighters primarily

use UHF frequency bands for communication

while commercial airliners use VI-IF bands.

IDENTIFICATION OF SHIPS

The problems of identification of friendly and

enemy ships are more like those of airborne

targets than they are like those of land surface

targets. Ships use a combination of tactical

information and direct target identification to

separate friends from foes.

Navy ships now have both Mark XII interrogators and transponders that allow positive friendly

identification. The ships are equipped with sophisticated navigational and communications equipment, thus antifratricide efforts among ships

through sharing of tactical and navigational

information comes naturally.

Chapter 2 related several historical incidents of

friendly fire between ships, and these are not

unknown today .20 With the strong emphasis on

carrier-based airpower, however, U.S. ships probably face a greater fratricidal danger from friendly

aircraft. The consequences would be much more

severe than for attacks on other aircraft but

fortunately the likelihood may not be as great.

Since the United States and its European allies

will have total control over the sea in most

foreseeable conflicts, there may be theaters in

which there is no reason for a friendly aircraft to

attack any ship.

There are several reasons to believe that

avoiding fratricide of ships will be easier, or no

more difficult, than avoiding fratricide of aircraft.

Modem warships are not as widely proliferated

around the world as are aircraft. Ships can afford

to carry more powerful transponders, surveillance, and communications equipment. Ships are

larger and slower than aircraft so some approaches to noncooperative identification of aircraft, for example, high resolution radar, should

work at least as well. Some noncooperative

techniques, for example, analysis of radio emission should work for ship identification just as

they do for aircraft identification, although ships

and aircraft will have different rules about radio

and radar silence. Other techniques, jet engine

modulation, for example, are simply not applicable. But still others might work better for ships

than aircraft: examples include, synthetic aperture radars, laser radars, and high resolution

infrared imaging. Because the country has far

fewer ships than aircraft, cost per platform is less

important for ships than for aircraft. Furthermore,

while perhaps not spacious, ships have much less

of a problem with packaging, power supply,

waste heat removal, and antenna placement than

do fighter aircraft.

9 Submarines

There is little current concern about fratricide

of submarines. Few nations possess them and

most that do are U.S. allies, so all submarines

could be assumed friendly in most limited conflicts. Furthermore, U.S. submarines are substantially different from those of other nations. In the

future, the problem may become worse, however.

Some countries hope to export small dieselelectric submarines. One can easily imagine a

19 U.S. Dep~ent of Transportatio~ Federal Aviation ~“ “stration, “Introduction to TCAS II,” March 1990.

ZO Dtig NATO exercises in october 1992, the U.S. aircraft carrier Saratoga accidentally fwed missiles at the Thrkish destroyer MU~VefIeL

killing five and wounding at least 15. See Eric Schmitg “U.S. Missiles Hit ‘Ih.rIcish Ship, Killing 5,” New York Times, Oct. 2, 1992, p, A~.
Chapter

conflict like that in the Persian Gulf War, taking

place perhaps a decade hence, in which both local

allies and local enemies are equipped with the

same German- or Russian-built submarines.

In principle, submarines could use cooperative

and noncooperative IFF systems analogous to

those used on aircraft. But whereas the aircraft

systems would depend primarily on radiofrequency electromagnetic energy, submarines

would use sound waves, magnetic fluctuations, or

some other signature. But submarines are different. The hard part of killing a submarine is not

attacking and destroying it—although that can be

a challenge under some circumstances; the hard

part is finding it. Submarine designers devote

considerable attention to further increasing the

difficulty of detecting submarines, largely by

making them as quiet as possible. Submariners

would strenuously resist any effort to have

submarines actively broadcast in response to

some identification hail, or to somehow increase

their boat’s signature to make cooperativepassive identification easier.

For the foreseeable future, therefore, avoiding

submarine fratricide will be based on the current

procedures for careful command and control of

areas of operation. Submarines now patrol individual, well-defined areas; any other submarine

that enters that area is considered hostile and open

to attack. Moreover, within assigned patrol areas,

surface ships do not engage in antisubmarine

activity (that is left to the resident submarine), but

any submarine found outside of assigned areas is

assumed hostile and could be attacked by surface

and airborne forces. This approach works but is

very flexible only with good communication

between submarines and surface ships. If assigned patrol areas can be reliably updated several

times a day, ships above and below the surface

can cooperate smoothly.

4—Avoiding Fratricide of Air and Sea Targets 67

A COMPREHENSIVE IDENTIFICATION

SYSTEM

No cooperative IFF system is perfect, so pilots

and ships’ crews hesitate to fire based solely on

the assumption that lack of an IFF reply means a

target is an enemy. Any shooter would prefer to

have positive evidence that a target is an enemy,

hence the motivation for noncooperative IFF

systems. Yet neither are noncooperative systems

perfect. Exercises on test ranges indicate that with

current technology a few percent of targets

identified as hostile are, in fact, friendly. This

error rate may be acceptable in a struggle for

survival, as was expected between NATO and the

Warsaw Pact. However, if in the future the United

States is engaged in a lesser conflict with overwhelming force ratios, then most of the aircraft in

the air at any given time will be friendly and even

a small rate of mistakenly identifying friends as

foes can result in the loss rates from fratricide

being as high as those from enemy action.

Cooperative and noncooperative systems can

work together to make each more effective than

either could be alone. Assume that a cooperative

question-and-answer type system were, say, 90

percent reliable. If this system were used to sort

all targets, then 10 percent of targeted friendly

forces would be classified as hostile, clearly an

unacceptably high value. But if a noncooperative

system were also 90 percent reliable, that is, it

classified friendly vehicles as hostile 10 percent

of the time, and all hostile-classified targets were

also queried by the cooperative system, then only

10 percent of 10 percent, or 1 percent, would slip

through both, assuming the two systems are

independent. 21 These numbers are picked only to

be illustrative, whether a 1 percent error rate is

acceptable will depend on the tactical situation

and political and military judgment.

Cooperative systems can even help identify

enemies, if operated in conjunction with noncooperative systems. Many noncooperative identifi21 In the red world, the systems may not be independent. Batde damage, for example, might both change the noncooperative signature and

put IFF transponders out of commission. In war, nothing is neat.
68 I Who Goes There: Friend or Foe?

cation techniques will discriminate friend from

foe on the bases of subtle differences, but will

require expensive, hence perhaps scarce, equipment. If this equipment is unable to examine all

possible targets, then cooperative question-andanswer systems could concentrate efforts on

ambiguous targets. For example, only those

targets that do not respond to a cooperative IFF

queries would be examined by noncooperative

techniques.

Currently, the technology required for cooperative question-and-answer IFF systems is more

developed than that for most noncooperative

systems. The Services see the advantages of

noncooperative IFF but that longer term goal

should not erode efforts to improve the reliability

of cooperative question-and-answer IFF by the

application of technology that is near-term or

in-hand.
Avoiding

Fratricide of

Land Surface

Targets 5

A

11 of the U.S. fratricidal casualties in the Persian Gulf

War were among land forces. Near-absolute dominance

of the air and Iraq’s inability to project power to sea

allowed conservative rules of engagement in those

media, which avoided accidental attacks on friendly forces

except in a couple of cases that did not result in casualties.

The fratricide of the Persian Gulf War was unusual compared

to that of past wars. As pointed out in chapter 2, the most striking

aspect at first was the apparently unprecedented high fraction of

total casualties resulting from fratricide. In addition, however,

the importance of each type of fratricide was different from other

large mechanized land battles. In World War II, for example, the

most deadly fratricide were the result of aircraft bombing

friendly troops. Surface-to-surface fratricide resulted most often

from indirect fire in which artillerymen fire at a target that they

could not see, The Persian Gulf War, in contrast, had an

unusually high fraction of fratricides from direct-fire weapons,

such as tanks, shooting mistakenly at other land targets.

Most of the U.S. personnel were mounted in vehicles; thus, not

surprisingly, most of the fratricide occurred when vehicles were

hit, so that current emphasis is on protection of vehicles, not on [

that of individual infantry. Helicopters are included in this ~

chapter; although helicopters are aircraft, their operation and

employment gives them more in common with surface vehicles

than fixed-wing airplanes, at least as far as fratricide technology

and equipment are concerned.

The next sections discuss general approaches to avoiding

fratricide of ground targets, a number of specific technologies

available to implement these approaches, and some of the

advantages and disadvantages of each approach and technology,

69
. . . . . .

70 I Who Goes There: Friend or Foe?

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US. armored vehicles destroyed by friendly fire during the Persian Gulf War were recovered and collected,

INCREASING KNOWLEDGE OF THE

TACTICAL ENVIRONMENT

Reviews of past cases of fratricide, including

those from the Persian Gulf, show that a prime

culprit is the shooter’s poor understanding of

where friends are, and even where he is himself.

A unit spreads further confusion among neighbors when—instead of being flatly lost—it believes it knows exactly where it is and reports an

incorrect location to other units. Thus, navigation

and communication are two vital keys to avoiding

fratricide.

B Navigation

Current multimillion dollar U.S. tanks do not

have compasses. This may seem astonishing until

considering that magnetic compasses are useless

inside 60-ton metal boxes. Alternatives-like

gyrocompasses—have been prohibitively expensive in the past and were often unreliable in the

rough environment of a tank. Nevertheless, the

first step for improving tactical knowledge of

mobile units requires improving their navigational tools. Fortunately, new technical developments make this easier.

During the Persian Gulf War, tanks used

equipment—including some off-the-shelf commercial equipment—that calculated latitude and

longitude from data received via radio pulses

from a network of satellites, the so-called Global

Positioning System or GPS. If desired, the same

principle could be applied on a local tactical scale

using airborne transmitters.1 Gyroscope compasses provide direction, and some, in particular

ring-laser gyroscopes, are improving in accuracy

and coming down in cost. Current plans call for

broad use of GPS and compasses, or azimuth

indicators, as the Army calls them.

Chapter 2 showed location uncertainty to be a

prime cause of fratricide from artillery. Global or

local positioning systems could provide artillery

batteries and their forward observers with accurate, consistent coordinates. Some proposals call

1 Briefing “Very Imw Frequency Identification Friend or Foe, ” Willie Johnsou U.S. Army Communications and Electronics Command,

Mar. 10, 1992.

,
— —

Chapter 5-Avoiding Fratricide of Land and Surface Targets 71

for use of positioning systems to increase fire

accuracy and perform last-instant IFF.

E Communication

Knowing location is just part of the job of

avoiding fratricide; each individual and unit must

inform nearby units of its location. One approach

is for each unit or vehicle to send its location to

some central distribution point. This might be a

ground-based or airborne communications node,

or it could be a satellite, perhaps the same one that

provides the location broadcasts as illustrated in

figure 5-1.

Communication of location could also take

place through shorter range networks, as illustrated in figure 5-2. Each vehicle could be a node

in a interwoven network of communicating vehicles. Each vehicle would transmit information

about itself as well as its neighbors. Thus, not

every pair of vehicles would need to be in

constant direct communication, In the figure, for

example, tanks numbered 3 and 5 might not be

able to communicate directly because of intervening terrain, but they can communicate by messages relayed via numbers 1 and 4. When tanks 3

and 5 then come into sight of one another around

the ridge, neither should be surprised. Systems

using these principles are now in development.

As one analyst has pointed out, this is a reversal

of how sensor networks have operated in the past:

sensor systems have been developed to find

information about the enemy, they collect information about the enemy and all the friendly forces

within range, and then-with only slight exaggeration—the information about friends is thrown

away.

2

Networks would allow the propagation of

information about foes as well as friends. Thus,

information about a hostile or ambiguous vehicle

sighted by any member of the network would be

available to each member of the network. In

and

‘d

SOURCE: Office of Technology Assessment, 1993.

principle, this type of communication allows

observers to ‘‘compare notes, ’ develop a composite picture, and thus get a better overall

identification. For example, one observer might

see an ambiguous vehicle, then try, and fail, to get

a reply to a IFF query. Another might have limited

information on its appearance, another detected

some suspicious radio signals, and so on. No piece

of information by itself is definitive, but all of it

together might be. The range of the communication

links is not a problem; indeed, considered strictly

from the point of view of avoiding fratricide, the

range does not need to be much more than, say,

double the range of the vehicles’ weapons.

A simple navigation-communication system

could be based on the current standard Army

tactical radio, the Single Channel Ground and

Airborne Radio System (SINCGARS).3 More

elaborate data exchanges will require radios with

higher data rates. Almost any system would be

most useful with some way to display the location

information inside the vehicle graphically.

2 Briefing entitled, “Fratricide Prcventiou ” Mark Fine, U.S. Army Communications and Electronics Command, Mar. 10, 1992.

3 See ‘‘Combat Identification, Data Pose Battlefield Awareness, ” Signa/, November 1992, pp. 37-39 and Mark Tapscott, “SINGARS

Upgrades Moving to Full Battlefield Communications, ’ Dqfense Electronics, vol. 25, No. 1, January 1993, pp. 29-32.
- . - — - . . . . - . . . - . . . . — - . . -.

72 I Who Goes There: Friend or Foe?

Figure 5-2—A Ground-based Communications

Net for Exchange of Location and

Identification Information

@

SOURCE: Office of Technology Assessment, 1993.

M IFF Through Exchange of Location

Information

Navigation and communication systems can be

used as a type of IFF device, one in which

identification is based not on vehicle characteristics or the exchange of codes, but on location

information. Take as an example a direct-fire

weapon like a tank. A navigation system could

provide each tank with an accurate position, and

a communication system could provide the positions of all friendly tanks within range. As part of

the current firing sequence, the tank gunner uses

a laser range-finder to determine the target’s

range. While current standard equipment on tanks

does not provide gun bearing, that is, the direction

in which it is shooting, the navigation system

could provide that information as well.

The tank gun’s computer or free-control system, knowing its own location and the range and

bearing of the target, can quickly calculate the

exact location of the target. This location can be

compared to the locations currently reported by

friendly vehicles and, if there is no match, the

target could be assumed hostile. (One might want

further conflation in case it is a friend with

malfunctioning equipment.)

If the current register of locations shows a

match, the answer is somewhat ambiguous. A

match only means that a friendly vehicle is at the

same location, within the accuracy of the system,

not that the target in the gun sights is a friend. The

accuracy may be dozens of meters and the true

friend may be obscured behind a clump of trees.

Other approaches following this general theme

are possible. For example, just before the gun

frees, a radio or laser signal could be sent out

containing the message: “Attention! I am about

to shoot at a target at the following coordinates,

if you are sitting on that spot, you should tell me

now.” Obviously, the message, and reply, would

have to be encrypted to keep the enemy from

exploiting the system. The speed of the system is

also important. Tank crews are trained to get a

round off within ten seconds of first detecting a

target; good crews can do it within six seconds.

Any IFF procedure that takes “only” a second

significantly increases engagement time.

IDENTIFICATION SYSTEMS

Even a very effective navigation-communication system probably will be unable to offer

perfect friend and foe identification; an additional

system devoted to IFF may also be needed. The

simplest cooperative IFF system allows the observer to remain passive, as illustrated in figure

5-3a. The target vehicle might use characteristic

markings to identify itself as friendly. In the

Persian Gulf War, the vehicles were marked with

an inverted ‘V’ made with an infrared-reflective
——— — ——— -- —. —— —— —

Chapter 5-Avoiding Fratricide of Land and Surface Targets 73

Figure 5-3-Approaches to Identification of

Friend and Foe

‘“*

“ *

c’*

‘“*

SOURCE: U.S. Army.

4

r, ,7

“\\

‘ /r

tape or paint that showed up on infrared imaging

devices while being fairly unobtrusive visually.

1 Beacons

The target vehicle might instead broadcast a

signal in all directions, identifying itself as

friendly, as illustrated in figure 5-3b. This is the

principle of the so-called “DARPA Lights” and

“Budd Lights.”4 Attaching flashing lights to

combat vehicles may seem unwise, since they

reveal the vehicles’ position to the enemy as well,

but these particular lights are only visible in the

near-infrared. In the Gulf War, the Allied forces

were widely equipped with infrared imageintensifiers and the Iraqis were not. In addition,

the DARPA Light is fitted with an adjustable

shroud that blocks ground observers’ views of the

light while keeping it visible from aircraft. This

simple security measure was useful, again, because of limitations of the enemy: the Allies had

total air dominance leaving no Iraqi airborne

platforms to observe DARPA Lights from above.

(DARPA Lights were acquired and ready to

deliver to the Gulf, but the conflict ended just

before shipment.)

The Thermal Identification Device, or TID, is

another beacon system in limited current production. The TID is a simple bent metal sheet in the

shape of a roof. The sheet is heated electrically on

one side to generate a thermal signal. The other

side reflects the cool thermal image of the sky.

The sheet is mounted on a short mast and an

electric motor rotates the sheet. Thus an observer

seeing the TID through an infrared image will see

an alternating bright and dark spot.5 See figure

5-4. The disadvantages of the TID include lack of

The ‘‘DARPA Light’ is a simple infrared beacon

visible only through night-vision goggles.

4 me -e @@t ~ve ~~ck &,mu5e of its s~~~ t. tit of a pop~ ~t bevemge, but the trmmitter was ori@mlly so named titer

its inventor, Henry ‘‘Bud’ Croley at the U.S. Army Night Vision Laboratory who, along with Wayne Antesberger, holds U.S. patent number

4862164 on the device.

s Bnefmg entitled, ‘‘Thermal Identi17cation Device (TID) for Combat Identificatio~’ John R. Gres@ Night Vision and Electro-optics,

Night Vision Laboratory, Ft. Belvoir, Virginia (undated).
. ——. .- . . . . . . . - . . . . . . . . .-

74 I Who Goes There: Friend or Foe?

Figure 5-4-The Thermal Identification Device (TID)

SOURCE: U.S. Army.

security (any enemy with the proper thermal

sights can see it as well as other friends can) and

unreliability (apparently the exhaust plume from

the engine of the M-1 tank can obscure the TID

from certain angles).

Near-infrared blinking lights, such as the

DARPA and Budd Lights, have two related

drawbacks. First they are visible to anyone, friend

or foe, with near-infrared night-vision imageintensifiers, which are cheap and widely available

Manual control

Laser activation

through the mail for about a thousand dollars.

Thus, any enemy might have at least a few

devices that could detect the beacons. Second,

they are not visible to the far-infrared imaging

devices used to aim the guns and other weapons

on U.S. armored vehicles. The TID avoids these

short-comings. Whereas the near-timed image

intensifiers are relatively inexpensive, farinfrared viewers are a hundred thousand dollars or

more, and correspondingly fewer countries have
Chapter 5-Avoiding Fratricide of Land and Surface Targets [ 75

the devices widely deployed. The TID also

radiates at the wavelengths at which the farinfrared targeting viewer is most sensitive.

Future systems operating on the same principle

could use continuous omnidirectional radio transmissions. Signals sent by radio would have longer

range than visible or infrared light, especially in

fog, rain, dust, or smoke. Of course, special

provisions must be made to keep an enemy from

intercepting and exploiting the signals. Possibilities include spread-spectrum signals-described

in the previous chapter--or time-synchronized

signals. Either approach forces an enemy to listen

to radio noise over a wide range-of frequency

bandwidth or time-and filter out a signal, while

friendly forces, knowing the waveforms or the

time sequence pattern, can listen only for the

signal.

I Question-and-Answer Systems

Having friendly targets broadcast only when

interrogated by another friendly shooter provides

additional security against enemy intercept and

exploitation of identification signals. This approach is illustrated schematically in figures 5-3c

and 5-3d.

Queries

The query signal could be a laser or some radio

pulse. The query pulse should be directional,

otherwise on a complex battlefield each tank’s

query would set off all tanks’ responses and

matching up queries and responses would be

hopelessly complicated.

The queries should also be encrypted to authenticate them as coming from friends. This keeps

the enemy from exploiting the system. The enemy

might, for example, suspect that U.S. vehicles lie

camouflaged along a tree line but not know

where. If sweeping the whole treeline with a laser

or radio pulse caused all the U.S. weapons to send

out IFF replies, they would reveal their positions,

so the response must come only after receipt of a

valid, encrypted query.

A potentially cheap IFF approach would be

adapting the existing laser range-finders now

fitted on U.S. tanks. A danger of this approach is

that the laser signal will not reliably penetrate

smoke, fog, and dust. This may not cause a

problem for the laser’s range-finder function—

after all, ranging the target, the dust cloud around

it, or the tree next to it is good enough to get a hit

with a flat trajectory weapon like a tank gun. But

if the laser did not penetrate intervening dust, then

the target would never get the query and would

never send off a friendly response.

The query signal would be sent through a

simple directional antenna aligned with the weapon.

It could be, for example, fixed to the barrel of the

tank gun or to the turret much as the laser

range-finder is now. The same simple directional

antenna would then naturally be lined up to pick

up the signal from the particular target in question

and not any other.

The Army’s current near-term solution will use

a millimeter wave radio beam as the query signal.

Millimeter waves can penetrate obscurants, like

dust, and they can be fairly narrowly focused.6

Replies

The reply signal could be any of those described above for a passive observer with much

the same advantages and disadvantages. Like the

query, the reply signal would have to be encrypted in some way that the enemy could not

reproduce,

Since the reply would be sent out only when the

system is properly queried, somewhat less attention could be given to avoiding intercept by the

enemy. For example, some proposed systems

would determine the general, but not exact,

direction of the query and return a bright, broad

laser beacon to show that the target is friendly,

accepting that the beacon would sometimes be

6 U.S. Army, Combat Identification System Program Office, Ft. Meade, MD, ‘‘Report to the Committees of the United States Senate and

House of Representatives on the Combat Identification Program, ” January 1993.
— . . -. —.- . - . . . .- . . .

76 I Who Goes There: Friend or Foe?

seen by enemies. Alternately, omnidirectional

radio beacons, illustrated in figure 5-3c, could

announce that the target is friendly. Omnidirectional broadcast is much simpler because it

removes any requirement for steering an antenna—very quickly!—in a particular direction.

A directional reply, shown schematically in

figure 5-3d, would provide additional security by

making enemy intercept less likely. One clever

approach would use the interrogating laser as its

own reply signal by reflecting the laser back to its

origin using a comer reflector. (A corner reflector

is just a set of reflective surfaces in the shape of

the inside of the comer of a cube. The geometry

of the surfaces is such that no matter which

direction a light beam enters, it is reflected back

out in exactly that direction.) The reply would be

authenticated by modulating or chopping the

query pulse in some way, for example, by turning

on and off liquid crystal windows covering the

comer reflector. This particular approach, using

lasers, would be unreliable in smoke or dust.

Radio frequencies could penetrate better and

could use the same principle with the authentication provided by vibration of the reflective

surfaces to produce a detectable Doppler shift in

the return signal or by rapidly changing the

impedance of the reflecting antenna-similar to

the pre-World War II proposals for varying

dipoles on aircraft.7

DISMOUNTED INFANTRY

Most of the effort for IFF devices has centered

on the identification of vehicles, not people. At

present, programs examining exclusively the

problem of identification of dismounted infantry

are in the planning stage. The Army intends to

fund dismounted infantry IFF programs in the

coming and subsequent fiscal years. Infantry

almost always work closely with vehicles of some

sort and any vehicle-mounted system will also

help prevent mistaken attacks on friendly infanThese three images are of the same tank on a test

range. The top is a close-up taken in visible light at

midday. The tank as seen at night through infrared

‘‘image intensifiers’ at a range of 500 meters is shown

in the middle image. The bottom image is the tank seen

through the same device but at 1500 meters. Modern

optics and electronics allows the detection of vehicles

beyond the range at which they can be reliably

identified.

T Briefing entitled, “Achieving Covert Communications and Ground-Combat Identification Using Modulated Scatterers,’ E.K. Miller and

D.M. Metzger, Mechanical and Electronic Engineering, Ims Alamos National Laboratory (Mar. 11, 1992).
Chapter 5-Avoiding Fratricide of Land and Surface Targets 77

try. Moreover, navigational and communications

improvements that increase tactical knowledge

will reduce fratricide of infantry as well as

vehicles, even without specific new IFF capabilities.

One of the quick fixes used in the Persian Gulf

and mentioned already was the small, batterypowered blinking infrared light called the Budd

Light. Its flashing is invisible to the unaided

human eye but shows up clearly at night through

night-vision goggles or other near-infrared imageintensifiers. The device is cheap and easily

produced by components from retail electronics

stores. Being so widely available, it hardly counts

as an IFF device but it can be a useful command

and control device. For example, one combat unit

may know that another unit is somewhere in front

of it in a group of trees but not know exactly

where. Getting the two units coordinated by

describing features at night over the radio is

difficult, but a request to turn on the infrared

blinkers for five seconds could make relative

positions clear in an instant, and thus help avoid

fratricide.

Future research will include work on techniques specifically directed toward infantry identification. Some of these ideas are modern incarnations of World War I infantry identification

efforts that included sewing mirrors on the backs

of trench coats to aid identification by friendly

aircraft overhead. Notional proposals include:

fabrics that reflect millimeter waves or fabrics

and dyes that reflect only very specific wavelengths chosen to match up with the wavelengths

detected by targeting sensors; fabrics and dyes

that luminesce under specific laser illumination;

retro-reflectors on combat uniforms; and active

infrared displays on the uniforms.8

‘‘BuddLights’ are invisible to the naked eye but show

up clearly through night-vision goggles.

NONCOOPERATIVE IDENTIFICATION

Development of noncooperative identification

of ground targets is perhaps at an even earlier

stage than it is for air targets, but some ideas have

surfaced. Just as for air targets, the simplest

identification technique is based on the outward

appearance of the vehicle. Again, as for air

targets, this simple approach is made very complex by the proliferation of U. S., British, French,

Russian, and other weapons throughout the world.

A straightforward improvement in identification capability would come from improvement in

imaging devices, for example, higher resolution

for infrared detectors, laser radars that provide

three dimensional images, and so on.

More subtle clues to identity might be provided

by, for example, vibrations of the surface of the

vehicle, detectable by Doppler radar. Doppler

radar shows some promise for the identification

of helicopter because of the characteristic Doppler shifts caused by the rotating blades.9

Sensors might be able to pick up characteristics

of the vehicle exhaust, even detecting differences

in fuel type,10 or sensors could look at the

8 ~ ~I~Omatlon paper: Identification Friend or Foe for the Individual soldier, ’ Robin St. Pere, U.S. Army, Natick RD&E Center, Oct. 6,

1992.

s Briefiig entitled, “Radar Helicopter Ident~lcation, ” Gcrardo Melcndez, EW/RSTA Directorate, Us. -Y CO~unications ~d

Electronics Command (undated).

10 Briefing entitled, ‘ ‘Laser Radar Effluent Sensor,” Guil Hutcheson, Ims Alarnos National Laboratory (undated).
— — — — . . . . . . . .- - - . . . - . . .

78 I Who Goes There: Friend or Foe?

reflectivity of the vehicle in several spectral

ranges.

ll For ground combat application, each of

these techniques that depend on detection of

subtle spectral differences should be approached

with a healthy skepticism, since transmission of

radiation through the dirty, dusty, smoky, foggy

air of the battlefield will often be the fundamental

limit to their performance. In addition, one must

consider the effects of trees, buildings, and

intervening terrain.

Some sensor systems have been developed to

detect enemy vehicles on the battlefield. For

example, the Remotely Monitored Battlefield

Sensor System, or REMBASS, uses a combination of acoustic, seismic vibration, magnetic, and

infrared sensors to detect vehicles. With some

added sensitivity, each of these techniques might

be able not just to detect, but identify, vehicles.

These sensors are typically short range and fixed

so they are probably better at providing tactical

intelligence about enemy vehicles to a communications network than at providing the information

directly to a shooter.

CURRENT PROGRAMS

A quick review is worthwhile to repeat what is

hypothetical and what is under active consideration or development. The Army divides its

development efforts into four time categories.

The “Quick Fix” was intended to get something

into the hands of troops immediately. Quick fixes

include the Budd and DARPA Lights, receivers

for satellite transmissions of global positioning

data, and the infrared-reflective “thermal” tape

that were rushed into service during the Persian

Gulf War. The Thermal Identification Device

described above is another quick fix.

After the Persian Gulf War, the Army acquired

20,000 Budd lights, which are to become logistic

stock items, and contracted for 120,000 square

feet of thermal tape. The Army also has the 8,000

DARPA Lights acquired during the Persian Gulf

War. The Army will acquire 300 TIDs, or the

parts required for rapid assembly. Production will

beat Tobyhanna Army Arsenal. This will provide

enough TIDs for an armored brigade. (Note also

that the extreme simplicity of the TID should

allow rapid surge production.) The Army also has

bought, or is in the process of buying, over 10,000

global position receivers called Small Lightweight Global Positioning Receivers, or SLGRs

(pronounced “slugger”).

The near-term program aims to get something

in the field in five years or so. The ideal near-term

system should require little or no additional

research and development. A request for proposals sent to industry solicited numerous responses.

A test at Ft. Bliss, Texas examined many of the

proposed systems using actual combat vehicles

under realistic desert conditions.

12 The result of

that test was selection of a millimeter wave

question-and-answer system for near-term development and deployment. One of the disadvantages of a millimeter wave system is that it will be

difficult to incorporate into airplanes, but compatibility between aircraft and surface vehicles is

only a desirable characteristic for near-term

solutions and a requirement only for far-term

solutions. The Army has set a limit of $100

million for total costs to produce approximately

enough identification devices for 1,500 vehicles,

not enough to outfit the whole army but enough

for a substantial contingency force.

Mid- and far-term solutions are intended to

provide a more permanent solution in seven or

more years. These programs are now in the

exploratory stage.

11 ~e~e ~otio~ approaches are taken for a brief~ presented by Wayne Gr~6 “Electro-Optics (E-O) lkchnology for Positive Target

Identification%” United States Arrny, Night Vision and Elecro-Optics Directorate, Fort Belvoir, VA (un&ted).

IZ Tfiing and Doctrine Co remand, Combut ID Tech Demo, June 9, 1992. Because of limitations of the desert test sites, performance in

fog, ra@ or forest could not be tested.
Chapter 5--Avoiding Fratricide of Land and Surface Targets 179

TACTICS, DOCTRINE, AND TRAINING

The Army has not given as much explicit

attention to avoiding fratricide in the past as

might be expected, but this is because troop safety

was a natural, integral part of coordination and

planning. The Army now believes, however, that

friendly fire requires special treatment in tactics,

doctrine, and training.

Some changes in tactics are possible. For

example, most of the Persian Gulf fratricides

occurred under conditions of reduced visibility,

either darkness or dust and haze. If the goal were

to reduce fratricide, then one easy solution would

be to never attack except under clear daylight

conditions. Remember, though, that low visibility

for U.S. forces often translates into no visibility

for enemy forces not equipped with infrared or

image-intensifying viewers. Night attacks reduce

the enemy’s effectiveness, including his ability to

inflict casualties, and thus reduce casualties

overall.

Nevertheless, technical advantages enjoyed by

the United States, compared to a wide spectrum of

potential adversaries, could allow changes in

tactics. For example, in the Persian Gulf, U.S.

forces could often see, hit, and kill Iraqi targets

that could not even see the forces shooting at

them. Under these conditions, more cautious,

deliberate attacks might be able to keep both

fratricidal and enemy-inflicted casualties down.

Training is extremely important to avoiding

fratricide in future conflicts. The Army’s training

centers now pay special attention to fratricide

incidents and collect the information for an

on-going “lessons-learned’ study. Firing ranges

are now equipped with both enemy and friendly

targets to practice ‘ ‘Don’t Fire! situations.

Simulation is an important part of modern

training. In the past, simulators have been much

better at depicting the day-lit world than the night

world seen through infra-red viewers. Yet most of

the fratricide in the Persian Gulf occurred under

some sort of reduced visibility. Simulation for

training is a rapidly progressing field and simulation of poor-visibility conditions must be supported in future programs.

CONCLUSIONS

Ground combat illustrates most clearly the

vital importance of tactical knowledge of the

battlefield to avoiding fratricide. Indeed, by some

estimates, the majority of fratricide could be

avoided by improvements in navigation and

communication without a dedicated IFF system.

For the foreseeable future, however, IFF devices

will probably also be desired to compensate for

gaps in tactical knowledge.

Navigation-communication systems and IFF

systems will be pursued in parallel but, when

comparing costs, one should keep in mind that

avoiding fratricide is just one advantage of

improved knowledge of the battlefield. Better

information will increase maneuverability, flexibility, control and coordination of units and fire,

and, hence, overall combat capability.

The Army’s preferred near-term solutions will

be difficult and expensive to incorporate into

fixed-wing aircraft, This alone might make it

unacceptable as a permanent solution if fixedwing aircraft are expected to continue to provide

close air support. One of the important policy

questions is how to allocate resources between

solutions that provide quick, but limited, results

and more permanent solutions, which admittedly

will take longer to implement.

The Army’s technology and equipment to

avoid ground combat friendly fire is primitive

compared to Navy and Air Force equivalents.

Army programs may need preferential funding for

several years just to catch up to the level enjoyed

by its sister Services today. The distribution of

fratricides in the Persian Gulf argues for this

relative shift in effort, at least until imbalances are

less pronounced.
.— —— ——

Absolute position, 35

“Accidental self-destruction,” 8

Accidents, fratricide due to, 9-10

Active systems, 39-40. See also Cooperative question-andanswer systems; Noncooperative question-and-answer

systems

Air targets, avoiding fratricide of, 49-66

Aircraft identification, history, 54-55

Allied operations, 4, 29

encryption keys and, 44

Amicicide, 8

Antifratricide systems

criteria, 45-46

cross-Service coordination, 6

doctrine, 47

emergence, 2

short-term and Iong-term goals, 5-6

tactical environment awareness vs. IFF, 46

training and simulation, 46-47

Army Training and Doctrine Command (TRADOC)

antifratricide measures, 46

fratricide definition, 9

ARSA-4 system, 65

Attack sequence, 32-33

Avoiding fratricide. See also Antifratricide systems

in air, 49-66

general considerations, 29-48

on ground, 69-79

at sea, 66-67

AWACS, 50

Battle management, 33,49-50

Beacons, 73-75

Black boxes, 46

Bradley, Gen. Omar, 13, 15

Bryan, C. D. B., 8

Budd Lights, 73-75,77,78

Index

CALL. See Center for Army Lessons Learned

Callaham, Lt. Commander, 20

Casualty report forms, 8

Casualty surveys. See Combat casualty surveys

Causes of fratricide

findings, 3

historical review, 7-28

Center for Army Lessons Learned (CALL), 19, 25-26

CID. See Combat Identification

Civil airborne transponders, 62-63

Mode S systems, 63-65

Civil-military coordination, 62-66

Classification, attack sequence step, 32

Combat casualty surveys, 1,21-23

data, 23

Combat Identification (CID), 33

Command and control failures, 10-15, 28

Commercial carriers, Mode S system and, 64

Communication

in battle management, 49-50

in tactical environment, 34, 71, 79

Communication failures, 28

Commuter carriers, Mode S system and, 64

Congressional issues, 5-6

Contests of less than national survival, considerations, 1,

31

Cooperative question-and-answer systems

advantages and disadvantages, 42

aircraft identification and, 56-57

limitations, 59-62

passive cooperative IFF measures, 59

passive measures, 59

queries, 75

replies, 75-76

Coordination failures, 28

Cross-Service coordination, 4,6

81
. ——

82 I Who Goes There: Friend or Foe?

DARPA Lights, 73-75,78

Decision to attack, attack sequence step, 33

Definition of fratricide, 9

Denial, 43,61

Detection, attack sequence step, 32

Direct system of information, 39

Dismounted infantry IFF programs, 76-77

Doctrine, 33,47, 79

Doppler radar, 59,77

Dye-loaded shells, ordnance identification, 21

Eisenhower, Gen. Dwight D., 14

Electromagnetic spectrum, 40,41

Encryption. See Information security

Engagement ranges, 30,37

Equipment design, 10

Europe, Mode S system and, 63

Examples

accidents, 9-10

Civil War, 17-18

command and control failures, 10-15

fear of fratricide effects, 19-20

fire discipline failures, 15-16

identification failures, 17-18

navigation failures, 16-17

World War II, 12-15

Explicit rules of engagement, 37-38

Exploitation, spoofing, and denial, 43,60-61

FAA. See Federal Aviation Agency

Fatalities. See Losses

Fear of fratricide, tactical constraints due to, 18-20,

Federal Aviation Agency (FAA), joint military ATC

operations, 65-66

FEZs. See Fighter Engagement Zones

Fighter Engagement Zones (FEZs), 53

Findings, 2-5

Fire discipline failures, 15-16,28

Force ratio, 30

Fratricide Incident Report, 46

Free-fire zones, 12

Frequency allocation, 65-66

Frequency trends, 30-31

Friendly Fire, 8

Ft. Bliss, Texas, testing, 78

General aviation, Mode S system and, 64

General Officers Steering Committee, 6

Global position receivers, 78

Goto, Adm., 19

Ground targets, avoiding fratricide of, 69-79

Guderian, Gen., 15

High-resolution radars (HRR), 51-53

Historical review of causes

combat casualty surveys, 1, 21-23

general considerations, 7-9

Persian Gulf War, 7-8,26-28

prevalence of fratricide, 20-22

Summary, 26-28

tactical constraints due to fear of fratricide, 18-20,30

training center data, 24-26

types of fratricide, 9-18

Hooker, Gen. Joseph, 17

Hopkins, Dr. James, 21

HRR. See High-resolution radars

Human error, accidents due to, 10

Identification

command and control failures and, 11-12

findings, 4

improved, 30

Identification failures

examples, 17-18, 37

types, 35-36

Identification of Friend and Foe (IFF), 33

advantages and disadvantages of systems, 42-43

exchange of location information, 72

exploitation, spoofing, and denial, 60-61

frequency allocation and, 66

information security, 43-45

and knowledge of tactical environment, 34-35

Next Generation IFF, 59-62

range and, 38

rules of engagement, 35-38

sources of information, 39-40

system jamming, 61

Identification systems, 67-68,72-73

IFF. See Identification of Friend and Foe

30 Implicit rules of engagement, 38

Indirect fire weapons, 22

Indirect system of information, 39

Infantry, 75-76

Information security, 43-45

frequency bands and, 62

Mode 4, 57-59

Mode S and peacetime intelligence loss, 65

question-and-answer systems, 75-76

Interrogators and transponders

civil airborne transponders, 62-65

Mark X protocol, 56-57

Mark XII protocol, 56-62,66-67

Mark XV protocol, 56-62

TACIT, 60

Jackson, Gen. Thomas “Stonewall,” 17-18

JADO. See Joint Air Defense Operations

Jamming, IFF and, 61-62

Jet engine modulation, 51

JEZs. See Joint Engagement Zones

Joint Air Defense Operations (JADO), 53,56

Joint Engagement Zones (JEZs), 53,56

Jungle fighting, 16-17

Knowledge of tactical environment, 33,34-35,46-47,70-72,

79. See also Communication; Navigation
Index I83

L-band system, 56,62

Land targets, avoiding fratricide of, 69-79

Lessons learned. See Center for Army Lessons Learned

Location information exchange, 72

Long-range weapons, 22

IFF and, 38

Losses

comparison of numbers, 31

fraction of deaths due to fratricide, 1,2, 31

Malfunctions, 9-10

Mark X protocol, 56-57

Mark XII protocol, 56-59

limitations, 59-62

onboard ships, 66-67

Mark XV protocol, 56-59

improvements, 59-62

McNair, Lt. Gen. Leslie, 14

Medical records, 21

Mercer, Lt. Col. George, 7,8

MEZs. See Missile Engagement Zones

Mid-air collision prevention, 65

MILES. See Multiple Integrated Laser Engagement System

“Misadventure,” 8

Misidentification, 18, 28

Missile Engagement Zones (MEZs), 53

Mitchell, Gen. William “Billy,” 11

Mock combat. See Training and simulation

Mode S systems, 63-65

Multiple Integrated Laser Engagement System (MILES),

24-25

National Trainin g Center (NTC), 9,24-26

simulations, 46

Navigation, in tactical environment, 34-35,70-71,79

Navigation failures, 16-17,28

Next Generation IFF (NGIFF), 59-62

No-fire zones, 12

Noncooperative systems

advantages and disadvantages, 42-43, 44

future of, 50

ground targets and, 77-78

radar, 51-53

radio--emission intercept, 50-51

surface-to-air missiles, 53, 56

NTC. See National Training Center

Observer/target energy transmission routes, 39-40. See also

Cooperative question-and-answer systems; Noncooperative

question-and-answer systems

Occurrence patterns, 8-28

Operation COBRA, 12-14

Operation Desert Storm. See Persian Gulf War

Operation QUEEN, 14

Operation TOTALIZE, 14-15

Opposing forces, mock combat, 24-26

Ordnance identification, 21, 30-31

Passive systems, 39-40. See also Cooperative question-andanswer systems; Noncooperative systems

Patriot missile, 53,56

Persian Gulf War

equipment, 70

fratricide during, 1,2,7-8,26-28,69

friendly fire incidents, 1991, 27

Positive identification, 38

Prevalence of fratricide, 20-22

Psychological effects, 1-2, 31-32

Pyle, Ernie, 13

Radar, 51-53

Radio-emission intercept, 50-51

Record keeping, 8

Remotely Monitored Battlefield Sensor System (REMBASS), 78

Resource allocation, 5

Rules of engagement, 5, 33, 35-38

S-band system, 62

Sa’adah, Dr. David, 21, 22

SARTIS. See Shipboard Advanced Radar Target Identification System

Schrader, Lt. Col. Charles, 8,22

Scott, Adm., 19

Sea targets, avoiding fratricide of, 66-67

Selective Identification Feature (SIF), 57

Sensor networks, 71

Sensor systems, 77-78

Severity, measuring, 31-32

Shipboard Advanced Radar Target Identification System

(SARTIS), 56

Ships, identification, 66-67

Short-range weapons, IFF and, 38

Short-term versus long term goals, 5-6

SIF. See Selective Identification Feature

Simulations. See Training and simulation

Single Channel Ground and Airborne Radio System

(SINCGARS), 71

Situational awareness. See Knowledge of tactical environment

Small Lightweight Global Positioning Receivers (SLGRs),

78

Sources of identification information. See Identification of

Friend and Foe; Knowledge of tactical environment

Spoofing, 43,60

Submarines, identification, 66-67

Surface-to-air missiles, noncooperative IFF and, 53,56

TACIT See Time Authenticated Cryptographic

Interrogator/Transponder

Tactical constraints due to fear of fratricide, 18-20

Tactical environment. See Knowledge of tactical environment

TCAS. See Traffic Alert and Collision Avoidance System

Technical developments

beacons, 73-75
84 I Who Goes There: Friend or Foe?

findings, 4

infantry identification, 77

information security, 43-44

resource allocation for, 5

review, 78

weapon and ordnance improvements, 30-31

Tempo of battle, 30

Thermal Identification Device (TID), 73-75,78

Time Authenticated Cryptographic Interrogator/Transponder (TACIT), 60

TRADOC. See Army Training and Doctrine Command

Traffic Alert and Collision Avoidance System (TCAS),

65-66

Training and simulation, 4-5

antifratricide systems, 46-47

NTC mock combat, 24-26

review, 79

Transponders. See Interrogators and transponders

Types of fratricide, 9-18

Washington, Col. George, 7,8

WDMET. See Wound Data and Munitions Effectiveness

Weapons

aim and ordnance delivery, 33

misidentification due to similarities between, 18

range, 30, 38

types causing injury, 22

Wound Data and Munitions Effectiveness (WDMET), 22