The 91N6A page covers the Russian 91N6 Big Bird S-band surveillance and tracking radar family used in Almaz-Antey long-range air-defense architecture. Official export material describes the 91N6E as the S-400 radar that detects and tracks aerodynamic and ballistic targets while feeding the 55K6E command post; open specialist sources treat 91N6A(M)/91N6M as the later S-500 acquisition and battle-management form, while subtype-specific public detail remains limited.
Ukraine's military intelligence reported striking a Russian 91N6E radar complex from an S-400 Triumf system in occupied Crimea overnight on 2025-08-28; the row is limited to the directly named 91N6E variant rather than every 91N6A-family subtype.
Role detailsThe conflict row is based on direct 91N6E evidence from occupied Crimea rather than generic S-400 deployment reporting. The page remains a 91N6-family radar record, so the row should not be read as proof that every listed subtype, including 91N6A(M)/91N6M, was independently documented in that strike.
Source reference: Suspilne Crimea 91N6E Strike.
The 91N6 family is described as the Big Bird S-band search radar layer in Russian long-range air-defense systems. The radar is separate from the engagement radar: it builds the long-range air picture, tracks targets, supports identification, and passes radar information to command-post elements that can cue fire-control radars and launch units.
Long-range surveillance, target tracking, and battle-management radar information for S-400/S-500-family air-defense architecture.
Open sources distinguish 91N6, 91N6A, 91N6E, and 91N6A(M)/91N6M, but detailed subtype differences are not consistently public.
RUSI identifies the 91N6 Big Bird radar used in S-400 and S-500 complexes as produced by JSC NPO NIIP NZIK in Novosibirsk.
Source references: 91N6; S-400 "Triumph"; Defending Mother Russia's Skies; Disrupting Russian Air Defence Production.
Open sources use the 91N6 designator across domestic, export, and later modernized Big Bird radar forms; public descriptions do not always separate 91N6A, 91N6E, and 91N6A(M) details cleanly.
| Variant | Configuration | Designation notes |
|---|---|---|
| 91N6 | Baseline Big Bird surveillance radar | Radartutorial describes 91N6 as a surveillance and tracking radar for the SA-21/S-400 family, derived from earlier Big Bird architecture. Sources: 91N6 |
| 91N6A | Modernized S-400M form | Radartutorial identifies 91N6A as a modernization for S-400M Triumf systems. Sources: 91N6 |
| 91N6E | Export S-400 radar system | Rosoboronexport lists the 91N6E radar system in the S-400 export set and describes it as detecting and tracking aerodynamic and ballistic targets while feeding radar information to the 55K6E command post. Sources: S-400 "Triumph" |
| 91N6A(M) / 91N6M | Later S-500-family acquisition and battle-management form | RUSI and Air Power Australia describe the S-500 ensemble as including a 91N6A(M) air-surveillance and battle-management radar, with Air Power Australia cautioning that public detail is insufficient to infer design changes from the baseline 91N6. Sources: Defending Mother Russia's Skies, Almaz-Antey S-500 Triumfator M |
The 91N6-family radar is documented as the long-range search and battle-management sensor layer in S-400 architecture, with later 91N6A(M) reporting placing it in the S-500 radar ensemble.
| Compatible item | Item type | Compatibility evidence |
|---|---|---|
 | Long-range surface-to-air missile system | Rosoboronexport's S-400 export description lists the 91N6E radar system as the search-and-tracking radar that detects aerodynamic and ballistic targets and provides radar information to the 55K6E command post. Sources: S-400 "Triumph" |
 | S-400 command post | Rosoboronexport describes the 55K6E combat control post as processing radar information, distributing targets, issuing target designations, and interacting with neighboring and higher command systems; the same source says 91N6E radar information is provided to the 55K6E. Sources: S-400 "Triumph" |
 | Engagement and missile-guidance radar | Rosoboronexport separates the 91N6E search radar from the 92N6E multifunctional radar, which handles target acquisition, launch preparation, missile guidance, and automatic exchange with the 30K6E control system. Sources: S-400 "Triumph" |
 | S-400 towed launcher | Air Power Australia's S-400 architecture description places 5P85TE2 launchers downstream of the 30K6E battle-management layer, with 91N6E in the battle-management system and 92N6E engagement radars controlling fire units. Sources: Almaz-Antey 40R6 / S-400 Triumf |
 | S-500 acquisition radar | RUSI describes the S-500 ensemble as including both the 91N6A(M) air-surveillance and battle-management radar and the 96L6-TsP target-acquisition radar. Sources: Defending Mother Russia's Skies |
CSIS Missile Threat lists the S-400 Triumf entering Russian service in 2007, providing the parent architecture for the 91N6-family radar role.
Sources: S-400 Triumf
RUSI described the expected S-500 radar ensemble as including a 91N6A(M) air-surveillance and battle-management radar enhanced from the 91N6A associated with S-400.
Sources: Defending Mother Russia's Skies
Suspilne reported Ukraine's military-intelligence statement that a Russian 91N6E radar complex from an S-400 Triumf system was struck in occupied Crimea overnight.
Sources: Suspilne Crimea 91N6E Strike
RUSI's air-defense production paper identified the 91N6 Big Bird radar used in S-400 and S-500 complexes as produced by JSC NPO NIIP NZIK in Novosibirsk.
Sources: Disrupting Russian Air Defence Production
