AN/ALQ-172

A study in 1996 by analysts of the Battelle Memorial Institute determined problems with repair of the ALQ-172 resulted in the highest cost per flying hour (CPFH) of any system on the B-52. The United States Air Force instituted Engineering Change Proposal (ECP) 93 modifying the system's memory and processing capability. By fiscal year 1997 (FY97), it also reported a second system was needed on the aircraft for full threat protection.

Also in FY96, Air Staff directed the ALQ-172 be installed on AC-130H gunships replacing the non-supportable AN/ALQ-131 jamming pods. Also installed on special operations forces (SOF) AC-130U, MC-130H and MC-130E aircraft, two subsystems were installed; one forward and one aft, with a single common display and control unit. Other engineering differences on these aircraft involved adding low-band transmitters, antennae and antenna control units.

Upgrades have incorporated geolocation capabilities, advanced countermeasures and new technologies. Nine Line-replaceable units (LRUs) have been upgraded, with five of those tested as of mid-2024. The upgrades are part of the maintainability and reliability system (MARS) upgrade; a 10-year, $947 million project enhancing the performance of the B-52's electronic countermeasures systems. With continuing support and upgrades, the ALQ-172 is expected to be in service well into the 2040s.

Integrated with aircraft controls and displays, the system provides countermeasures capabilities for multiple sophisticated pulse, continuous wave, doppler and monopulse threats simultaneously. Using digital frequency discrimination (DFD) technology, the system is capable of determining pulse width, angle of arrival (AOA), and pulse-repetition frequency (PRF) of threat signals, deinterleaving and processing them.

In accordance with the Joint Electronics Type Designation System (JETDS), the AN/ALQ-172 designation represents the 172nd design of an Army-Navy electronic device for an electronic countermeasures system. The JETDS system also now is used to name Air Force systems.

• Weight per aircraft: 1,631 pounds
• LRUs per system: 7
• Systems per aircraft: 2
• Antennas per aircraft: 7
• Systems produced: 943 (over 6,000 LRUs)

• AN/ALQ-172(V)
• AN/ALQ-172(V)1 - on AC-130U and MC-130H aircraft
• AN/ALQ-172(V)2
• AN/ALQ-172(V)3 - on AC-130H Gunships

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• {{Annotated link|AN/ALQ-99}}
• {{Annotated link|AN/ALQ-101}}
• {{Annotated link|AN/ALQ-135}}
• {{Annotated link|AN/ALQ-218}}
• List of military electronics of the United States
• {{Annotated link|Joint Electronics Type Designation System}}

{{Reflist |refs=

{{Citation |url= https://www.forecastinternational.com/archive/disp_old_pdf.cfm?ARC_ID=1251 |format=PDF |title= ALQ-172(V) - Archived 03/2003 |date= March 2002 |website= Forecast International |access-date= December 20, 2024}}

{{Citation |url= https://www.l3harris.com/all-capabilities/alq-172-b-52-self-protection-system |title= AN / ALQ-172 B-52 Self Protection System |website= L3Harris |access-date= December 23, 2024}}

{{Citation |url= https://theaviationist.com/2024/07/12/upgraded-alq-172-tested/ |title= B-52’s Upgraded AN/ALQ-172 Self-Protection System Tested During Recent Flight |first= David |last= Cenciotti |date= July 12, 2024 |access-date= December 23, 2024 |website= The Aviationist}}

{{Citation |url=https://man.fas.org/dod-101/sys/ac/equip/an-alq-172.htm |title= AN/ALQ-172 Countermeasures System (CMS) |first= John |last= Pike |date= April 22, 2000 |website= FAS Military Analysis Network |access-date= December 23, 2024}}

{{Citation |url= https://www.defensedaily.com/l3harris-receives-u-s-air-force-contract-worth-up-to-947-million-for-an-alq-172/air-force/ |title= L3Harris Receives U.S. Air Force Contract Worth Up to $947 Million for AN/ALQ-172 |first= Frank |last= Wolfe |date= September 1, 2021 |access-date= December 23, 2024 |website= DefenseDaily}}

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• [https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104465/b-52h-stratofortress/ AF.mil - B-52H Stratofortress Fact Sheet]

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