AN/FSQ-7 Combat Direction Central
Cold War-era air defense command and control computer
The AN/FSQ-7 Combat Direction Central, referred to as the Q7, was a computerized air defense command and control system. It was used by the United States Air Force for ground-controlled interception as part of the Semi-Automatic Ground Environment (SAGE) network during the Cold War.
In accordance with the Joint Electronics Type Designation System (JETDS), the "AN/FSQ-7" designation represents the 7th design of an Army-Navy electronic device for fixed special combination system. The JETDS system also now is used to name all Department of Defense electronic systems.
An advancement of the pioneering MIT Whirlwind II digital computer design, and manufactured by IBM as prime contractor, the AN/FSQ-7 was the largest discrete computer system ever built. Each of the 24 installed machines weighed 250 tons. The AN/FSQ-7 used a total of 60,000 vacuum tubes (49,000 in the computers) and up to 3 megawatts of electricity, performing about 75,000 instructions per second for networking regional radars.
Primary functions
Installations in the USAF Semi-Automatic Ground Environment (SAGE) air defense network were configured as duplex systems, using a pair of AN/FSQ-7 computers to provide fault tolerance. One was active at any time, the other on standby. The standby system copied data from the active system to minimize switchover time if needed.
“AN/FSQ-7 Combat Direction Central” enters the record as cold War-era air defense command and control computer. Crown Archives preserves that source wording while asking what FSQ-7, Combat and Direction can confirm, complicate or overturn.
Why this record matters
“AN/FSQ-7 Combat Direction Central” is worth following because a concise public description often conceals a longer documentary argument. Here, FSQ-7, Combat and Direction provides the most credible route into that argument.
Contemporary correspondence, administrative files and participant testimony can test how later narratives organized the event or institution. The source revision retrieved here is dated Jul 19, 2026. The linked authority identifier is Q963418. The Library of Congress control number is sh2014001520. 1 of 2 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank.
Later summaries often reconcile disputed chronology or motive more neatly than the contemporary record permits. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Compare institutional narratives with records created by participants and affected communities. Dates and formal titles are useful anchors, but not substitutes for context.
- Event chronology
- Institutional context
- Locating named record creators
Contemporary correspondence, government or organizational records, oral histories and cited historical scholarship.
Three-step research path
- Establish the record: confirm the title “AN/FSQ-7 Combat Direction Central”, its source revision and the description used here.
- Expand the search: follow AN/FSQ-7 Combat Direction Central primary sources, AN/FSQ-7 Combat Direction Central archive and FSQ-7 research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “AN/FSQ-7 Combat Direction Central”?
- Which voices are present, absent or mediated by the institution?
- What chronology connects this entry to wider political or social change?
Search terms from this dossier
This entry incorporates text from “AN/FSQ-7 Combat Direction Central” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.