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Russian Su-35S Flanker-E: The Primary Air Superiority Threat to Ukraine's Airspace

· 13 min read · Category: Aviation / Russian Air Threat

1. Overview: Russia's Most Capable Fighter in the Ukraine War

The Sukhoi Su-35S "Flanker-E" (NATO reporting name) is Russia's most capable operational air superiority fighter as of 2026 — a heavily upgraded member of the Flanker family incorporating 4th-generation++ technologies that were developed partly in preparation for the Su-57 fifth-generation program. In the context of the Ukraine conflict, the Su-35S represents the primary fighter threat to Ukrainian aircraft and the deepest challenge to Ukraine's effort to establish meaningful aerial sovereignty over its own territory.

First delivered to the Russian Aerospace Forces (VKS) in 2014, the Su-35S was produced at a rate of approximately 16–20 aircraft per year at Komsomolsk-on-Amur (KnAAPO), and Russia's inventory reached approximately 100–120 Su-35S before the conflict reduced this total through combat losses. The aircraft's capabilities in radar detection range, engine thrust, and weapons capacity place it significantly above any aircraft Ukraine operated before F-16 deliveries — and the Su-35S retains meaningful advantages over the F-16AM MLU that Ukraine received.

2. Su-35S Performance Specifications

  • Length: 21.9 m
  • Maximum takeoff weight: 34,500 kg
  • Engines: 2× Saturn AL-41F-1S "Izdeliye 117S" — 14,500 kgf each with afterburner (thrust-vectoring nozzles); approximately 20% more thrust than Su-30SM's AL-31FP
  • Maximum speed: Mach 2.25 at altitude
  • Supercruise: Limited — approximately Mach 1.1 without afterburner
  • Service ceiling: 18,000 m
  • Combat radius: ~1,600 km (hi-lo-hi)
  • Hardpoints: 12 external; maximum weapons load 8,000 kg
  • Crew: 1
  • RCS (Radar Cross Section): approximately 1–3 m² (reduced vs earlier Flankers through some airframe treatments; not full stealth)

3. N035 Irbis-E Radar: Ukraine's Biggest Single Air Threat

The N035 Irbis-E ("Snow Leopard") passive phased array radar is the Su-35S's defining capability advantage and the single sensor that most threatens Ukrainian aviation:

  • Detection range against fighters: approximately 350–400 km against 3 m² RCS target; approximately 90 km against 0.01 m² (low-observable) target
  • F-16 detection range: against F-16's approximately 1.2 m² RCS, the Irbis-E detects at approximately 200–250 km — significantly beyond the F-16's APG-68 detection of the Su-35S at approximately 100–150 km
  • This range asymmetry is decisive: in a straight head-on intercept, the Su-35S pilot sees the F-16 on radar 80–100 km before the F-16 sees the Su-35S; the Su-35S can fire R-77-1 AMRAAMs at the F-16 before the F-16 has even acquired radar lock to fire back
  • Multiple target tracking: simultaneously track 30 air targets, engage 8 simultaneously — outperforming F-16 APG-68 which tracks 10, engages 6
  • Air-to-ground: SAR mapping, DBS (Doppler Beam Sharpening), ground moving target indicator; full multi-mode capability
  • Doppler capacity: excellent look-down/shoot-down against low-altitude targets — important for engaging Ukrainian aircraft flying NOE (nap of earth) profiles

4. Weapons System and BVR Capability

The Su-35S weapons configuration for air superiority missions:

  • R-77-1 (AA-12 Adder mod 1): Active radar homing BVR missile, effective range 80–110 km in representative engagements; fire-and-forget like AIM-120 AMRAAM; 12 can be carried in maximum BVR load
  • R-37M (AA-13 "Axehead"): Long-range active radar homing AAM with reported effective range 150–200+ km; specifically designed to engage AWACS, tankers, and UAVs at extreme range; R-37M has been used in Ukraine against Ukrainian Su-27/MiG-29 at BVR ranges up to 150+ km per Ukrainian official statements — a range at which no Ukrainian missile can retaliate
  • R-73M (WVR): High off-boresight short-range IR missile, carried 2× on wingtip rails
  • Ground attack: Full range of KAB-500/1500 guided bombs, Kh-31, Kh-59, FAB-UMPK glide bombs; full dual-role capability

The R-37M is particularly significant — its claimed operational range of 150–200+ km exceeds the AIM-120C-7's range of ~80–105 km and would exceed even the AIM-120D (~180 km) by some accounts. Ukraine's operational loss of multiple aircraft to what were assessed as ultra-long-range missile shots corresponds with R-37M employment.

5. OLS-35 IRST and Electronic Warfare Suite

  • OLS-35 IRST: Passive infrared search and track; detects fighter aircraft at 50–90 km in non-afterburner mode, 150+ km in afterburner; enables entirely passive (non-emitting) targeting — the Su-35S can track and fire R-73 without ever activating its radar, making it invisible to RWR-based air defense warning systems
  • L175V Khibiny-M ECM pod: Directional jamming against threat radar systems; can degrade APG-68 tracking at close ranges; significantly improves Su-35S survivability against SAMs
  • SPO-32 Pastel RWR: Detects and classifies radar threats; alerts pilot to F-16 radar lock-on; cues IRST and defensive maneuver
  • L402 ECM system: Integrated into aircraft avionics (not external pod); broadband jamming coverage

6. Russian Su-35S Fleet and Deployment

  • Pre-conflict inventory: approximately 100–120 Su-35S in VKS service
  • Primary conflict deployment: Southern and Western Military Districts; aircraft from Akhtubinsk (flight test), Belbek (Crimea, until Crimean airfield attacks), Primorsky Kray, Kursk Oblast air bases
  • Egypt sale: Egypt contracted for 24 Su-35 in 2019; US threatened CAATSA sanctions; deliveries were delayed and partial — potentially 6–10 aircraft delivered by 2024; Egypt retained aircraft despite US pressure
  • China Su-35 (previously sold 24 aircraft, 2015 Chinese order): China received 24 Su-35 in 2016–2018 but did not order more, having reverse-engineered key technologies; no longer relevant to Russia's operational inventory for Ukraine
  • Production continuation: KnAAPO continues Su-35S production but at reduced rate post-Western sanctions on avionics components; approximately 8–12/year estimated current production

7. Su-35S Tactics in Ukraine's Air War

Russian Su-35S employment in the Ukraine conflict:

  • Air superiority barrier patrols: Su-35S maintains CAP (Combat Air Patrol) orbits over and behind Russian lines, preventing Ukrainian aircraft from penetrating Russian-controlled airspace or achieving favorable engagement geometry
  • R-37M long-range shots: Most consequential tactic — the Su-35S fires R-37M from extreme range (100–200+ km) against Ukrainian aircraft detected on Irbis-E radar; Ukraine cannot fire back with equivalent range weapons; several Ukrainian Su-27/MiG-29 losses are attributed to this tactic executed from beyond Ukrainian counter-engagement range
  • Escort for strike packages: Su-35S escorts Su-34 strike aircraft and Tu-22M3 approaches, providing air cover against potential Ukrainian intercept attempts
  • SEAD escort: Khibiny ECM jamming from Su-35S provides degraded lethality against Ukrainian radar-guided SAMs defending strike packages

8. Su-35S and UMPK Glide Bombs

A significant evolution in Su-35S employment since 2024 has been systematic use as a FAB-500/1500 UMPK glide bomb carrier:

  • The Su-35S can carry 2–4 FAB-1500 M54 UMPK (1,500 kg bombs with glide kit) per sortie — each with a 600–700 kg warhead equivalent blast
  • Release from 12,000–14,000 m altitude at Mach 0.8–1.0 gives the UMPK glide kit a standoff range of 40–70 km — placing the releasing Su-35S well outside most front-line air defense coverage
  • Ukrainian counter: deployment of Patriot and NASAMS at medium depth behind the front line is the primary defense; Patriot PAC-3 MSE can engage the UMPK glide bomb in flight but the numbers required to intercept mass salvos exceeds Ukraine's Patriot missile inventory
  • Impact: approximately 70–80% of Russian tactical strike sorties in 2025–2026 use UMPK glide bombs rather than dumb bombs or cruise missiles — reflects available unit cost (~$30,000/UMPK kit vs $1M+/cruise missile)

9. Documented Su-35S Losses

Despite its performance superiority, Russia has lost a number of Su-35S aircraft in the conflict:

  • OSINT documentation (Oryx): approximately 15–22 Su-35S confirmed destroyed as of March 2026 — through a combination of Ukrainian SAM engagements, long-range Ukrainian strikes on Russian air bases, and rare air-to-air engagements
  • Most losses have not been in air-to-air combat — the Su-35S's radar and missile range superiority makes it largely safe from Ukrainian fighters in BVR engagements; losses have predominantly come from SAMs (Patriot, improved S-300) reaching into Russian air defense artillery zones, and from Ukrainian drone and missile strikes on air bases
  • Notable engagement: at least one Su-35S is assessed to have been destroyed by Patriot PAC-2 engaging at maximum range on a Su-35S conducting a glide bomb attack sortie, reaching into Russian airspace by the Patriot's extended engagement capability

10. F-16AM vs Su-35S: The Asymmetric Matchup

ParameterF-16AM MLUSu-35SAdvantage
Radar detection range (fighter)~150 km~250 kmSu-35S decisive
Primary BVR missileAIM-120C-7 (~105 km)R-77-1 (~110 km) / R-37M (~200 km)Su-35S at range; equal at medium BVR
Passive tracking (IRST)None standardOLS-35 (50–90 km)Su-35S
ECM self-protectionALQ-131 podKhibiny-M integratedComparable
Max speedMach 2.0Mach 2.25Su-35S slight
Thrust-to-weight~1.1:1~1.2:1Su-35S
SEAD capabilityFull (HARM + HTS)Limited (Kh-31P)F-16
NATO integrationFullNoneF-16
Supply chainStable WesternConstrained (sanctions)F-16
Crew workloadHigh (single pilot all systems)High (single pilot all systems)Equal

The matchup is genuinely asymmetric in Russia's favor for pure air-to-air at BVR ranges. Ukraine's F-16s are not expected to engage Su-35S in head-on BVR duels — the Su-35S will detect first and fire first with a missile the F-16 cannot yet respond to. Ukrainian doctrine adapts by avoiding the conditions where Su-35S advantages are maximized.

11. How Ukraine Counters the Su-35S Threat

  • Avoid BVR conditions: Ukraine's F-16s are not employed in air-to-air offensive sweeps toward Russian-controlled airspace where Su-35S is waiting; F-16 engagements are defensive interceptions of aircraft approaching Ukrainian positions
  • SAM coverage depth: Ukraine's Patriot batteries, extending their intercept reach with PAC-3 MSE into Russian-adjacent airspace, are the most effective counter to Su-35S that remains at medium range executing glide bomb attacks
  • Deception and threat: Ukrainian F-16s on defensive CAP create uncertainty for Su-35S crews about the direction and strength of Ukrainian fighter presence — even if the F-16 rarely achieves R-77M-range engagement, its presence degrades Su-35S free operation
  • Long-range strikes on Su-35S bases: Ukrainian long-range drone and Storm Shadow strikes on Russian air bases where Su-35S is stationed have destroyed aircraft on the ground — the most effective method of reducing the Su-35S threat that Ukraine has demonstrated
  • Future AIM-120D: If Ukraine receives AIM-120D (~180 km range), the range disadvantage to R-77-1 is closed; the R-37M remains a challenge, but the current asymmetry narrows significantly

FAQ

Can Ukraine's F-16 defeat the Su-35S in air-to-air combat?

In a straight head-on BVR engagement at medium altitude, the Su-35S has significant advantages: it will detect the F-16 first via Irbis-E at ~250 km vs APG-68's ~150 km, and can fire R-37M at ranges the F-16 cannot respond to with AIM-120C-7. However, air combat is rarely a controlled one-on-one scenario. In a scenario where F-16 has launch authority via AWACS cueing before Su-35S activates radar, or where F-16 approaches from a non-head-on geometry negating the radar range advantage, the F-16's AIM-120 remains competitive. Modern air combat outcomes are highly situational — system performance in ideal conditions doesn't determine all real-world encounters.

Why doesn't Russia achieve air superiority over Ukraine given the Su-35S advantage?

Russia's challenge is not individual aircraft capability — the Su-35S is genuinely superior to Ukraine's aircraft. Russia's constraints are: (1) Ukraine's dense, deep SAM network means Su-35S must stay well back from Ukrainian territory to avoid being shot down by Patriot; (2) Even with superior radar, finding and engaging a Ukrainian aircraft that is flying at 30 m in ground clutter behind terrain features is challenging; (3) Russia has limited numbers of Su-35S relative to the depth of Ukraine's territory; (4) Ukrainian strike missions use standoff weapons that don't require the F-16 to approach areas where Su-35S can engage freely.

Is the R-37M missile really shooting down Ukrainian aircraft from 200 km?

Ukrainian military officials have stated that multiple aircraft were lost to what appeared to be very long-range missile shots consistent with R-37M employment. Western analysts assess R-37M practical range at 100–150 km in operational (non-test) conditions against targets that are maneuvering and dispensing countermeasures. The exact engagement geometries are classified. What is clear is that Ukraine suffered aircraft losses to apparent BVR engagements at ranges beyond their ability to counter — the R-37M is the only Russian weapon in service capable of these engagement distances.

How many Su-35S aircraft are left in Russia's active fleet?

Estimated 80–100 operational Su-35S as of early 2026, after accounting for approximately 15–22 documented losses and roughly 8–12 new production aircraft added annually. Russia retains a substantial Su-35S fleet — the losses, while significant, have not materially degraded the force capability. The more significant constraint on Su-35S employment is SAM vulnerability in the Ukraine air defense environment and the strategic cost of losing high-value aircraft versus the limited gains of deeper air incursion over Ukraine.

What are the limitations of the Russian Su-35S Flanker-E: The Primary Air Superiority Threat to Ukraine's Airspace in combat?

Like all weapon systems, the Russian Su-35S Flanker-E: The Primary Air Superiority Threat to Ukraine's Airspace has operational limitations including range constraints, logistical requirements, crew training demands, and vulnerability to countermeasures. These are addressed in the analysis section of this article.

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