Electronic Warfare: Towed Decoys Could Improve Survivability of Current
Navy Aircraft (Letter Report, 09/04/97, GAO/NSIAD-97-94).

GAO reviewed the Department of Defense's (DOD) acquisition plans for the
ALE-50 towed decoy system and the Radio Frequency Contermeasures System
(RFCM), which includes a more advanced towed decoy, focusing on whether
towed decoys could improve the survivability of certain Navy and Air
Force aircraft.

GAO noted that: (1) DOD's effort to improve the survivability of its
aircraft through the use of towed decoys has demonstrated positive
results; (2) according to test reports and test officials, the ALE-50
has done very well in effectiveness testing and the future RFCM decoy
system is expected to be even more capable; (3) the Air Force is
actively engaged in efforts to field towed decoy systems on a number of
its current aircraft, including the F-15, F-16, and B-1, while the Navy
is planning towed decoys only for its future F/A-18E/F; (4) in the year
2010, almost 50 percent of the Navy's tactical fighter inventory will
still be current generation fighter aircraft such as the F/A-18C/D, even
if new F/A-18E/Fs are procured at the rates desired by the Navy between
now and then; and (5) improving the survivability of the F/A-18C/D, as
well as other current Navy and Marine Corps aircraft, potentially offers
the opportunity to save additional aircraft and aircrew's lives in the
event of future hostilities and also addresses congressional concerns
expressed for F/A-18C/D survivability.

--------------------------- Indexing Terms -----------------------------

 REPORTNUM:  NSIAD-97-94
     TITLE:  Electronic Warfare: Towed Decoys Could Improve 
             Survivability of Current Navy Aircraft
      DATE:  09/04/97
   SUBJECT:  Military procurement
             Air defense systems
             Electronic warfare
             Military aircraft
             Testing
             Defense capabilities
             Missiles
             Defense contingency planning
             Radar equipment
IDENTIFIER:  F/A-18C/D Aircraft
             F/A-18E/F Aircraft
             F-15 Aircraft
             F-16 Aircraft
             B-1 Aircraft
             ALE-50 Towed Decoy System
             Navy Integrated Defensive Electronic Countermeasures Program
             ALQ-131 Jammer
             ALQ-135 Jammer
             Airborne Self-Protection Jammer
             DOD Quadrennial Defense Review
             DOD Joint Tactical Electronic Warfare Study
             DOD Radio Frequency Countermeasures System
             ASPJ
             
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Cover
================================================================ COVER


Report to Congressional Committees

September 1997

ELECTRONIC WARFARE - TOWED DECOYS
COULD IMPROVE SURVIVABILITY OF
CURRENT NAVY AIRCRAFT

GAO/NSIAD-97-94

Electronic Warfare/Towed Decoy Systems

(707143)


Abbreviations
=============================================================== ABBREV

  ASPJ - Airborne Sself-Protection Jammer
  DOD - Department of Defense
  QDR - Quadrennial Defense Review
  RFCM - Radio Frequency Countermeasures System

Letter
=============================================================== LETTER


B-272628

September 4, 1997

Congressional Committees

We have completed our review of the Department of Defense's (DOD)
acquisition plans for the ALE-50 towed decoy system and the Radio
Frequency Countermeasures System (RFCM), which includes a more
advanced towed decoy.  The RFCM is part of the Integrated Defensive
Electronics Countermeasures System being developed for some Navy and
Air Force aircraft.  Our objective was to determine whether towed
decoys could improve the survivability of these aircraft.  In
addition, because Congress has expressed concern for F/A-18C/D
survivability, we are issuing this report to bring to your attention
the opportunity towed decoy systems offer to potentially enhance
survivability of the F/A-18C/D. 


   RESULTS IN BRIEF
------------------------------------------------------------ Letter :1

DOD's effort to improve the survivability of its aircraft through the
use of towed decoys has demonstrated positive results.  According to
test reports and test officials, the ALE-50 has done very well in
effectiveness testing and the future RFCM decoy system is expected to
be even more capable.  The Air Force is actively engaged in efforts
to field towed decoy systems on a number of its current aircraft,
including the F-15, F-16, and B-1, while the Navy is planning towed
decoys only for its future F/A-18E/F. 

In the year 2010, almost 50 percent of the Navy's tactical fighter
inventory will still be current generation fighter aircraft such as
the F/A-18C/D, even if new F/A-18E/Fs are procured at the rates
desired by the Navy between now and then.  Hence, improving the
survivability of the F/A-18C/D, as well as other current Navy and
Marine Corps aircraft, potentially offers the opportunity to save
additional aircraft and aircrew's lives in the event of future
hostilities and also addresses congressional concerns expressed for
F/A-18C/D survivability. 


   BACKGROUND
------------------------------------------------------------ Letter :2

Traditionally, DOD's combat aircraft have used on-board electronic
warfare devices called jammers for self-protection against
radar-controlled weapons, including missiles and anti-aircraft
artillery.  These jammers emit electronic signals from the aircraft
to try to impede or deny the threat radar's ability to locate the
aircraft.  DOD's existing self-protection jamming systems for its
tactical aircraft have limitations against certain threats, and these
threats are expected to be improved.  DOD has modified existing
systems, such as the Air Force's ALQ-131 used on the F-16 and the
ALQ-135 on the F-15, and has developed a newer system, the Navy's
Airborne Self-Protection Jammer (ASPJ), which is being used on some
F-14D and F/A-18C/D aircraft.  As we have previously reported,
however, testing after deployment has shown that the modified jammer
systems have had problems,\1 while operational testing of ASPJ and
other jammers showed they were unable to meet effectiveness criteria
against certain classified threats.\2

In an attempt to overcome the limitations of the on-board jammers,
the services are acquiring two new towed decoy systems, the ALE-50
and the RFCM, to enhance survivability against the radar-controlled
threats.  The ALE-50 towed decoy system is in production, while the
future RFCM system is in development.  The ALE-50's towed decoy
component generates and emits its own signals that are intended to
lure an incoming radar-guided weapon away from the aircraft by
presenting a more attractive target.  To provide further improvement
for selected Air Force and Navy aircraft, the RFCM is to provide more
sophisticated techniques than the ALE-50.  A jamming device called
the techniques generator carried onboard the aircraft produces
jamming signals that are transmitted by fiber optic cable to the RFCM
decoy for transmission. 

Both decoys are single use systems.  Once deployed from the aircraft,
the decoy's tow line is severed prior to return to base.  Each
aircraft is to carry multiple decoys, so if one is destroyed by enemy
fire or malfunctions, another can be deployed.  Therefore,
substantial inventories of decoys are required to sustain potential
combat operations.  The services expect that these decoys will
improve survivability of their aircraft against radar-controlled
threats compared to the current technique of emitting the jamming
signals directly from the aircraft. 


--------------------
\1 Electronic Warfare:  Need to Strengthen Controls Over Air Force
Jammer Programs (GAO/NSIAD-90-168, July 11, 1990) and Electronic
Warfare:  Most Air Force ALQ-135 Jammers Procured Without Operational
Testing (GAO/NSIAD-95-47, Nov.  22, 1994). 

\2 Airborne Self-Protection Jammer (GAO/NSIAD-97-46R, Jan.  29,
1997.)


   TOWED DECOYS CAN ENHANCE
   SURVIVABILITY
------------------------------------------------------------ Letter :3

Classified test results show that the ALE-50 towed decoy offers
improved effectiveness against radar-controlled threats, including
some threat systems against which self-protection jammers have shown
little to no effectiveness.\3

Moreover, the future RFCM decoy system is expected to further improve
survivability due to its more sophisticated jamming techniques. 

Recognizing the potential offered by these towed decoy systems to
overcome the limitations of using just on-board jammers, such as the
ASPJ, the Air Force is actively pursuing the use of towed decoys for
its current aircraft.  It has done the necessary modifications to add
the ALE-50 to the F-16, an aircraft slightly smaller than the Navy's
F/A-18C/D, and to the B-1, a much larger aircraft.  The Air Force is
also considering use of the RFCM decoy system on the F-15, which will
use its existing on-board jammer instead of the techniques generator,
and on the B-1, as well as several other aircraft.  The Navy plans to
equip only its future F/A-18E/F aircraft with a decoy system. 

The ALE-50 decoy system is to be used by the Air Force on 437 F-16
and
95 B-1 aircraft.  In addition to the ALE-50 components such as the
launcher and controller installed on the aircraft, the Air Force
plans to procure 17,306 ALE-50 decoys to meet operational
requirements.  The Navy plans to buy 466 ALE-50 decoys.  These will
be used for F/A-18E/F testing and contingencies after the aircraft's
deployment until the RFCM decoy is available.  The ALE-50 program
cost is estimated at about $1.2 billion. 

The Navy's estimated RFCM cost for its F/A-18E/F aircraft is about
$2.6 billion.  The Navy's plan is to procure enough RFCM systems and
spares to equip and support 600 of its planned buy of 1,000 F/A-18E/F
aircraft.  For 600 F/A-18E/F aircraft, the number of decoys to be
procured to meet operational needs is 18,000.  (These estimates
predate the May 1997 decision of the Quadrennial Defense Review (QDR)
to recommend a reduction in the number of F/A-18E/Fs.)

The future RFCM decoy system is also being considered by the Air
Force for its B-1 aircraft, part of its F-15 fleet, and several other
Air Force manned and unmanned aircraft.  If the Air Force buys the
RFCM system for the B-1 and the F-15, which would use its existing
onboard jammer instead of the RFCM techniques generator, the
estimated cost, including 9,107 decoys, is about $574 million. 


--------------------
\3 Performance against specific threat systems is considered
classified. 


   CURRENT NAVY AIRCRAFT WILL NOT
   BE PROVIDED WITH TOWED DECOYS
------------------------------------------------------------ Letter :4

In contrast with the Air Force, which intends to use decoys to
improve the survivability of its current aircraft, current Navy
combat aircraft will be at a comparative survivability disadvantage
since they will not be provided with a decoy system.  In particular,
because F/A-18E/Fs will not be replacing all of the C/D models in the
Navy/Marine Corps inventory in the foreseeable future, adding a towed
decoy system to the F/A-18C/D potentially offers the opportunity to
save additional aircraft and aircrew's lives in the event of
hostilities. 

In the year 2010, more than 600 of the Navy's tactical fighter
inventory objective of 1,263 aircraft will still be current
generation fighters such as the F/A-18C/D.  This will be true even if
F/A-18E/Fs are procured at the Navy's desired rates of as high as 60
per year.  At the post-QDR suggested rate of 48 per year, almost 50
percent of the current generation aircraft will still be in the fleet
in the year 2012. 

DOD and the Navy have done studies to determine whether towed decoys
could improve the survivability of the F/A-18C/D.  DOD's Joint
Tactical Electronic Warfare Study and an analysis conducted by the
Center for Naval Analyses concluded that the addition of a towed
decoy system to the F/A-18C/D would provide a greater increase in
survivability for that aircraft than any jammer, including the ASPJ. 

In limited flight testing on the F/A-18C/D, the Navy demonstrated the
ALE-50 decoy could be deployed from either a wing station or the
centerline station of the aircraft.  While the Navy acknowledges that
towed decoys can enhance aircraft survivability, it does not consider
these flight tests to have been successful because of the following
suitability concerns.  According to the Navy (1) the tow line can
come too close to the horizontal tail or the trailing edge flap when
deployed from a wing station, making it unsafe or (2) the tow line
can be burned off by the engine exhaust or separated by abrasion if
deployed from the centerline station. 

The Navy's report on the wing station testing stated that tow line
oscillation led to lines breaking on several flights, but did not
state that the decoy system was a flight safety risk nor that there
was any contact with the horizontal tail or flaps.  Concerning the
centerline station tests, several tow lines were burned off or
otherwise separated from the aircraft by abrasion during maneuvering
flights.  A reinforced tow line later solved these problems and the
Navy is continuing testing on the F/A-18C/D from the centerline
station.  Based on these test results, the Navy now intends to deploy
the ALE-50 decoy from the centerline of the fuselage of the
F/A-18E/F. 

The Navy also maintains that even if the decoy could be successfully
deployed from the F/A-18C/D wing or centerline station, for actual
operations, it could not afford to trade a weapon or fuel tank on a
wing or centerline station for a towed decoy system.  Further, the
Navy considers modification of the C/D model's fuselage for internal
carriage of the decoy to be unaffordable due to volume, weight,
power, and cooling constraints that would have to be addressed. 

The Air Force has modified a wing pylon to successfully deploy towed
decoys from the F-16's wing while avoiding major aircraft
modifications and without sacrificing a weapons station or a fuel
tank.  The Navy, however, has not done the technical engineering
analyses to determine the specific modifications necessary to
accommodate a towed decoy on the F/A-18C/D either from the wing or
the centerline without affecting the carriage capability
unacceptably. 


   SURVIVABILITY OF F/A-18
   AIRCRAFT HAS BEEN A
   CONGRESSIONAL CONCERN
------------------------------------------------------------ Letter :5

Congress has expressed concerns regarding F/A-18C/D survivability. 
The Report of the Senate Appropriations Committee on the National
Defense Appropriations Act for Fiscal Year 1997 directed the Navy to
report on the advantages and disadvantages of using various
electronic warfare systems to improve F/A-18C/D survivability.  In
addition, Congress provided $47.9 million in fiscal year 1997 funding
not requested by DOD to buy 36 additional ASPJs for 3
carrier-deployed squadrons to meet contingency needs. 

The Navy could have addressed the congressional concern for C/D
survivability in the required report by including analysis of the
improvement offered by incorporating the ALE-50 and RFCM towed decoy
systems.  In completing the required report, however, the Navy did
not include any analysis of survivability benefits from using towed
decoys because it maintains, as described above, that there are
unacceptable impacts associated with towed decoys on the F/A-18C/D. 


   AGENCY COMMENTS AND OUR
   EVALUATION
------------------------------------------------------------ Letter :6

In commenting on a draft of this report, DOD agreed that towed decoy
systems could enhance aircraft survivability, but stated the Navy had
conducted an engineering analysis that concluded any installation
option of a towed decoy on the F/A-18C/D has unacceptable operational
and/or safety of flight impacts.  In response to our request for this
analysis, the Navy provided us with a paper discussing the
feasibility of installing a towed system on the F/A-18C/D.  This
paper concluded that the options considered had risks or created
operational concerns but did not conclude that these options were
unacceptable.  Furthermore, the paper did not consider all possible
options. 

With regard to the safety of flight issue, the Navy stated that the
decoy or towline might contact aircraft control surfaces such as the
flaps or the horizontal stabilizers if deployed from a wing station. 
The Navy's summary of wing station test results, however, does not
show any evidence of such contact.  The Navy has expressed no concern
about a safety of flight issue when deploying the decoy along the
aircraft's centerline and continues to fly test missions with the
towed decoy, deploying it from a pod on the centerline of an F/A-18D
aircraft.  Furthermore, the Navy intends to install the system in the
fuselage and deploy towed decoys from the centerline of the E/F model
aircraft.  In addition, the Air Force incorporated the ALE-50 on to
the F-16 without loss of a weapon station or fuel tank and without
having to undertake major aircraft modifications, demonstrating that
it is possible to adapt a towed decoy system to an existing aircraft
without creating unacceptable tactical impacts. 

DOD did not concur with the recommendations that were set forth in a
draft of this report.  In the draft, we had suggested that (1) in
preparing its congressionally required report, DOD consider F/A-18C/D
aircraft upgraded with RFCM and ALE-50 towed decoy systems and (2)
the Navy do the necessary engineering analyses of the modifications
needed to integrate towed decoys into F/A-18C/D and other current
Navy aircraft.  DOD completed the congressionally required report
without implementing our first draft recommendation.  We continue to
believe, however, that the Navy needs to explore ways to improve the
survivability of its current aircraft and, therefore, should do a
detailed engineering analysis of the modifications needed to adapt
the towed decoy to the F/A-18C/D.  DOD's comments are reprinted as
appendix I in this report. 


   RECOMMENDATION
------------------------------------------------------------ Letter :7

We recommend that the Secretary of Defense direct the Secretary of
the Navy to make a detailed engineering analysis of the modifications
needed to adapt the towed decoy to the F/A-18C/D. 


   MATTERS FOR CONGRESSIONAL
   CONSIDERATION
------------------------------------------------------------ Letter :8

In light of the demonstrated improvement in survivability that
analyses and test results indicate towed decoy systems can provide,
and recognizing that in the year 2010 almost 50 percent of the Navy's
tactical fighter inventory will still be current generation fighter
aircraft such as the F/A-18C/D, Congress may wish to direct the Navy
to find, as it has done for its F/A-18E/F and the Air Force has done
for the F-16, cost-effective ways to improve the survivability of its
current aircraft. 


   SCOPE AND METHODOLOGY
------------------------------------------------------------ Letter :9

To accomplish our objective of determining whether towed decoys could
improve survivability of Air Force and Navy aircraft, we examined DOD
and contractor analyses of adding towed decoy systems and reviewed
Air Force and Navy ALE-50 test results from testing on a variety of
aircraft.  We interviewed officials from the Office of the Secretary
of Defense, the Navy, and the Air Force involved in the acquisition
and testing processes of towed decoy systems.  We also interviewed
contractor personnel involved in the development, integration, and/or
production of towed decoy systems. 

We performed our work at the Offices of the Secretaries of Defense,
the Navy, and the Air Force; F-15, F-16, and B-1 System Program
Offices at the Air Force Material Command, Wright-Patterson Air Force
Base, Ohio; F/A-18 and Tactical Air Electronic Warfare Program
Offices at the Program Executive Office for Naval Tactical Aviation,
Naval Air Systems Command, Washington, D.  C.; the 53rd Wing and Air
Force Operational Test and Evaluation Detachment, Eglin Air Force
Base, Florida; and selected contractor locations, including
McDonnell-Douglas Aircraft, Lockheed-Martin, and Rockwell
International. 

We performed our review from February 1996 to July 1997 in accordance
with generally accepted government auditing standards. 


---------------------------------------------------------- Letter :9.1

We are sending copies of this report to the Secretaries of Defense,
the Navy, and the Air Force; the Director, Office of Management and
Budget; and other congressional committees.  We will make copies
available to others upon request. 

Please contact me on (202) 512-2841, if you or your staff have any
questions concerning this report.  Major contributors to this report
are listed in appendix II. 

Louis J.  Rodrigues
Director, Defense Acquisitions Issues

Congressional Addressees

The Honorable Strom Thurmond
Chairman
The Honorable Carl Levin
Ranking Minority Member
Committee on Armed Services
United States Senate

The Honorable Ted Stevens
Chairman
The Honorable Daniel K.  Inouye
Ranking Minority Member
Subcommittee on Defense
Committee on Appropriations
United States Senate

The Honorable Floyd D.  Spence
Chairman
The Honorable Ronald V.  Dellums
Ranking Minority Member
Committee on National Security
House of Representatives

The Honorable C.W.  Bill Young
Chairman
The Honorable John P.  Murtha
Ranking Minority Member
Subcommittee on National Security
Committee on Appropriations
House of Representatives

The Honorable Richard C.  Shelby
Chairman
The Honorable J.  Robert Kerrey
Vice Chairman
Select Committee on Intelligence
United States Senate

The Honorable Porter J.  Goss
Chairman
The Honorable Norman D.  Dicks
Ranking Minority Member
Permanent Select Committee on Intelligence
House of Representatives




(See figure in printed edition.)Appendix I
COMMENTS FROM THE DEPARTMENT OF
DEFENSE
============================================================== Letter 



(See figure in printed edition.)



(See figure in printed edition.)



(See figure in printed edition.)



   GAO COMMENTS
----------------------------------------------------------- Letter :10

Following are our comments on the Department of Defense's (DOD)
letter dated May 5, 1997. 

1.  Our draft report included references to the comparability of
F/A-18E/F and C/D survivability, and it was provided to DOD for
comment prior to the decision to produce the F/A-18E/F.  As DOD
states, this decision has now been made.  Consequently, we have
deleted references to the comparability of the F/A-18E/F and C/D
models.  The issue of F/A-18C/D survivability remains important,
however, because E/F models will not replace all of the current C/D
models in the inventory in the foreseeable future. 

2.  Test results for towed decoys on the F/A-18C/D and other
information provided by DOD and the Navy do not support DOD's
statements.  The safety of flight issue, according to the Navy,
arises from the concern that the decoy or towline might contact
aircraft control surfaces such as the flaps or the horizontal
stabilizers if deployed from a wing station.  The Navy's summary of
wing station test results does not show any evidence of such contact. 
According to the test report, the Navy did find that aircraft
vortices behind the wing created aerodynamic instability in the
towline, but the report does not conclude that this potentially
jeopardized aircraft flight safety.  Additionally, the Navy has
expressed no concern about a safety of flight issue when deploying
the decoy along the aircraft's centerline, and use of a reinforced
towline appears to have eliminated the burnoff/abrasion problem. 
Thus, the Navy continues to fly test missions with the towed decoy,
deploying it from a pod on the centerline of an F/A-18D aircraft, and
intends to install the system in the fuselage and deploy towed decoys
from the centerline of the E/F model aircraft.  This evidence
indicates that Navy concerns about a high degree of difficulty, and
severe volume, weight, power, cooling, and aircraft aerodynamics
issues associated with installing towed decoys may not be
insurmountable. 

As for unacceptable tactical impacts associated with towed decoy
installation, the Air Force has overcome this problem on the F-16,
and we presume that the Navy may also be able to find an integration
solution for the F/A-18C/D that avoids unacceptable tactical impacts
if it continues to pursue alternatives.  The Navy did not abandon
towed decoy installation for the F/A-18E/F because of early problems
with abrasion and heat breaking the towline.  Instead, it pursued
alternatives.  The solutions for the F-16 and F/A-18E/F do not have
to be the only alternatives considered for the F/A-18C/D. 

3.  The Navy and DOD did provide us with additional information
intended to bolster its broad assertion of unsuitability.  However,
the information provided was not an "engineering analysis" (implying
a technical document of some depth), but is instead a rather
superficial "installation feasibility study" that while identifying
risk areas associated with installing the towed decoy on the
F/A-18C/D does not conclude that all installation options have
unacceptable operational and/or safety of flight impacts. 

4.  According to the Navy's feasibility study, 220 pounds is the
weight of the towed decoy system mounted in a pod.  According to the
same study, if the system's launch controller is mounted in the
aircraft's fuselage, the bring-back weight is reduced by only 140
pounds.  In any case, since studies and test results indicate the
ALE-50 system can provide significant improvements in survivability,
the Navy needs to determine whether loss of a relatively small amount
of bring-back weight is worth the increased risk of losing aircraft
to radar-guided missiles. 


MAJOR CONTRIBUTORS TO THIS REPORT
========================================================== Appendix II


   NATIONAL SECURITY AND
   INTERNATIONAL AFFAIRS DIVISION,
   WASHINGTON, D.C. 
-------------------------------------------------------- Appendix II:1

Michael Aiken
Terrell Bishop
Paul Latta
Terry Parker
Charles Ward


*** End of document. ***