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 DOT&E Director, Operational Test & Evaluation  
FY98 Annual Report
FY98 Annual Report

F-15 Tactical Electronic Warfare System (TEWS)
(AN/ALQ-135 Band 1.5)

Air Force ACAT III Program: Prime Contractor
Total Number of Systems:163Northrop Grumman
Total Program Cost (TY$):$317M 
Average Unit Cost (TY$):$1938MService Certified Y2K Compliant


The F-15 Tactical Electronic Warfare System (TEWS) AN/ALQ-135 Band 1.5 contributes to full-dimensional protection by improving individual aircraft probability of survival through improved air crew situation awareness of the radar guided threat environment, cueing both active and passive countermeasures in the Band 1.5 frequency spectrum, and adding a waveform select feature for jamming optimization against specific threats. The F-15 TEWS consists of the AN/ALR-56C radar warning receiver (RWR), the AN/ALQ-135 internal countermeasures set (ICS), the AN/ALQ-128 electronic warfare warning set, and the AN/ALE-40/45 countermeasures dispenser. TEWS provides electronic detection and identification of both surface and airborne threats. In addition, it allows for activation of appropriate countermeasures including electronic jamming and dispensing of expendables such as chaff and flares.

Integral to the F-15 TEWS, ALQ-135 ICS is an internally mounted responsive jammer designed to counter surface-to-air and air-to-air threats with minimum aircrew activity. The system is sized to fit into the limited space of the F-15E interdiction aircraft's ammunition bay although upgraded components have also been retrofitted into the F-15C air superiority variant. The system has an improved reprogramming support capability that rapidly changes pre-flight message software in response to changing threat parameters and mission requirements. The ALQ-135 ICS has been fielded in several phases to provide incremental improvements to jamming coverage. Phase one has provided an initial Band 3 capability which includes integrated operation with both the F-15E fire control radar and the ALR-56C RWR. ALQ-135 ICS Band 3 capability currently allows full interoperability and robust jamming techniques against modern pulse-Doppler radar. Full system capability requires the installation and integration of Band 1.5 hardware to provide coverage against threats operating in the lower frequency range.


ALQ-135 is an outgrowth of an early 1980s feasibility demonstration and a follow-on quick reaction capability high band jammer developed to counter rapidly changing threats. Developmental problems precipitated a restructuring of the ALQ-135 ICS program in 1988 to provide incremental capabilities. A TEWS EOA of Phase I Band 3 ICS was planned in July 1989 to support F-15E IOC. However, technical problems delayed the start of EOA until July 1990. Fifteen sorties were flown against threat simulators on the Eglin AFB, FL range complex in air-to-air and air-to-ground mission scenarios. ICS demonstrated the capability to identify and counter most current threats in a limited density environment, but the test indicated that additional software and hardware development was necessary to achieve desired operational capabilities.

AFOTEC was directed to conduct an interim TEWS OA to characterize the operational capabilities and limitations of the fielded systems and assess readiness for IOT&E. The OA concluded in September 1994 recommended five ALQ-135 improvements: (1) interoperability with the APG-70 radar; (2) system response times; (3) built-in-test (BIT) displays; (4) BIT accuracy; and (5) low band frequency coverage for the F-15E (i.e., Band 1.5).

FOT&E operations conducted by the United States Air Force Air Warfare Center (USAFAWC) concluded in August 1996 and addressed ALQ-135 Band 3 ICS interoperability with the APG-70 radar as well as improvements in the BIT displays. USAFAWC is currently conducting FOT&E at the Multi-Spectral Threat Environment range located at Eglin AFB to evaluate intra-flight (wing man) compatibility-the advanced threat de-interleave processor (for improved system response times) and jamming effectiveness and BIT upgrades.


The ALQ-135 Band 1.5 TEMP was approved in May 1998. Developmental testing of the ALQ-135 began in June 1998 with initial focus on integration and interoperability testing between the ALQ-135 ICS with Band 1.5 installed and other F-15E weapons systems such as the ALR-56C radar warning receiver. Currently, developmental tests are focused on response time measurements as well as correct radio frequency (RF) threat identification and correct RF counter technique generation. Developmental testing is proceeding on schedule.

Operational testing is scheduled to begin in February 1999 and continue through August 1999. Operational test planning is proceeding on schedule. DOT&E approval of the OT test plan is expected in December 1998.

Band 1.5 integration into the ALQ-135 ICS extends frequency coverage into the lower bands of the electromagnetic spectrum, complementing Band 3 frequency coverage. COIs anticipated for Band 1.5 integration include: (1) does the Band 1.5 system provide effective threat countermeasures to reduce threat lethality in its intended operational environment; (2) is the Band 1.5 system interoperable with TEWS and compatible with the F-15E operational environment; and (3) does the operational readiness of the Band 1.5 system support 5-15E mission requirements.

DOT&E staff will continue to monitor and participate in test planning activities through the attendance of ALQ-135 Band 1.5 Test Plan Working Group meetings. DOT&E staff will review for approval finalized versions of the ALQ-135 Band 1.5 TEMP and OTP prior to commencement of OT.


Although no operational test for the ALQ-135 Band 1.5 equipment has occurred, DOT&E staff are monitoring ongoing DT events. Suitability data on production representative ALQ-135 Band 1.5 equipment collected during DT should increase the sample size of data available for OT suitability analysis. Monitoring of DT integration/interoperability, response time, threat identification and countermeasure response testing is providing both DOT&E staff and OT test teams with technical insight into the ALQ-135 system and its operation. Insight gained from monitoring DT activities will allow OT test teams to optimize the adequacy of OT test plans.

Operational test planning is progressing on schedule. All major effectiveness and suitability performance parameters will be evaluated. The focus of testing will include: (1) testing against a variety of available airborne and ground based threats; (2) operating Band 1.5 equipment with aircraft systems (and jointly) during multi-ship formations; and (3) operating Band 1.5 equipment concurrently with other F-15 TEWS systems; e.g., Band 3 jamming equipment.

The program intends to follow the predict-test-compare methodology by utilizing modeling and simulation and ground test facilities to minimize risk and optimize open-air tests. Ground test facilities will be utilized to create unique, dense signal environments that otherwise would not be found on open-air test ranges. Thirty-five flight test missions are currently scheduled in support of DT&E. Preliminary risk reduction will be conducted utilizing the Air Force's Multi-Spectral Threat Environment Facility. Twenty-six additional flight test missions will be flown in support of IOT&E. Flight test missions for both DT&E and IOT&E will be conducted primarily at the Western Test Range (WTR). China Lake will be utilized for threats not available at WTR.

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