Overview

The Sukhoi Su-15 (NATO reporting name: "Flagon") was a twin-engine supersonic interceptor aircraft developed to defend Soviet airspace against high-altitude bomber threats. Entering service in 1965, it became one of the most numerous Soviet interceptors with over 1,500 built, serving exclusively with PVO (Soviet Air Defense Forces) until retirement in the early 1990s. The Su-15 is historically notable for shooting down Korean Air Lines Flight 007 in 1983.

Historical context

Development began in the late 1950s as the T-58 prototype under Pavel Sukhoi's design bureau. The aircraft evolved from the Su-11 interceptor, adopting a delta wing configuration and side-mounted engine intakes for improved performance. First flight occurred in May 1962, with production starting in 1965 at Novosibirsk Aviation Plant.

The Su-15 was designed during the height of Cold War tensions when Soviet air defense planners prioritized intercepting NATO bombers (B-52, Vulcan, Victor) penetrating Soviet airspace at high altitude. The aircraft featured ground-controlled intercept (GCI) guidance, allowing controllers to vector Su-15s onto targets detected by early warning radar networks.

The type remained highly classified until Western observation in 1967, with limited public appearances throughout its service life due to strategic sensitivity.

Specifications

Commonly cited specifications (Su-15TM "Flagon-F" baseline):

Dimensions:

  • Length: 21.33 m (70 ft)
  • Wingspan: 9.34 m (30 ft 8 in)
  • Height: 5.10 m (16 ft 9 in)
  • Wing area: 36.6 m² (394 sq ft)

Weights:

  • Empty weight: 11,210 kg (24,713 lb)
  • Normal takeoff: 17,900 kg (39,462 lb)
  • Maximum takeoff: 18,000 kg (39,683 lb)

Powerplant:

  • Engines: 2 × Tumansky R-13F2-300 turbojet engines
  • Thrust: 40.2 kN (9,040 lbf) dry, 66.7 kN (14,990 lbf) with afterburner each

Performance:

  • Maximum speed: Mach 2.4 (2,500 km/h, 1,553 mph) at altitude
  • Cruising speed: 1,150 km/h (715 mph)
  • Combat radius: 725 km (450 mi) with internal fuel
  • Ferry range: 1,650 km (1,025 mi)
  • Service ceiling: 18,100 m (59,383 ft)
  • Rate of climb: 228 m/s (44,882 ft/min)
  • Wing loading: 489 kg/m² (100 lb/sq ft)
  • Thrust/weight: 0.76 (at normal takeoff weight with afterburner)

Armament:

Primary air-to-air missiles:

  • 2 × R-98 (AA-3 "Anab") semi-active radar homing (SARH)
  • 2 × R-98T (AA-3 "Anab") infrared homing
  • Or 4 × R-60 (AA-8 "Aphid") short-range IR missiles

Gun armament: None (interceptor role did not require guns in Soviet doctrine)

Hardpoints: 4 × underwing pylons (inner and outer pairs)

Crew:

  • Su-15: 1 (pilot only)
  • Su-15UT/Su-15UM: 2 (pilot, instructor) in tandem cockpits

Design characteristics

Aerodynamics

Delta wing configuration: Pure delta planform optimized for high-speed, high-altitude interception

Side-mounted intakes: NACA-type rectangular inlets positioned beside fuselage, avoiding nose radar interference

All-moving horizontal tail: Fully articulated stabilators for pitch control

No leading-edge devices: Delta wing generates vortex lift at high angles of attack without slats/flaps

High wing loading: 489 kg/m² enabled stable weapon platforms at altitude but limited low-altitude maneuverability

Avionics and sensors

Oryol-D ("Eagle") radar (Su-15TM):

  • Type: S-band pulse-Doppler
  • Detection range: 65 km (40 mi) vs. bomber-sized targets
  • Tracking range: 45 km (28 mi)
  • Look-down capability: Limited performance vs. low-altitude targets

RSIU-5V datalink: Ground-controlled intercept guidance from PVO command posts

SRZO-2 "Khrom-Nikel" IFF: Identification Friend or Foe transponder

SAU-58 autopilot: Coupled with GCI for automatic intercept geometry

No infrared search/track (IRST): Relied entirely on radar and ground guidance

Limitations

No internal gun: Doctrine emphasized missile-only armament, leaving Su-15 vulnerable in close combat

Limited maneuverability: High wing loading and pure delta wing made tight turns impossible without excessive energy loss

Ground-controlled intercept dependency: Pilot had minimal autonomous search capability; required ground radar vectoring

Short range: 725 km combat radius necessitated forward staging bases for deep intercepts

Poor visibility: Canopy framing and lack of bubble design restricted pilot awareness

Variants and developments

Production variants

Su-15 (T-58, "Flagon-A", 1965-1969): Initial production with Oryol-58 radar, 2 × R-8M missiles

Su-15T ("Flagon-D", 1969-1971): Improved radar, titanium wing spars reducing weight

Su-15TM ("Flagon-F", 1971-1979): Definitive variant with upgraded Oryol-D radar, more powerful R-13F2-300 engines, compatibility with R-60 missiles—most produced version

Su-15UT/UM ("Flagon-C/G"): Two-seat trainer variants with tandem cockpits, reduced fuel capacity

Experimental variants

T-58M: Prototype with uprated AL-7F-1 engines (Mach 2.65 performance), not adopted

Su-15-30: Proposed upgrade with R-33 long-range missiles (developed into MiG-31 instead)

Su-15bis: Late-1970s modernization proposal with look-down/shoot-down capability, not funded

Operational deployment

Service timeline

  • 1962: First flight of T-58 prototype
  • 1965: Initial operational capability with PVO interceptor units
  • 1967: Western intelligence identifies "Flagon-A" designation
  • 1971: Su-15TM variant enters mass production
  • 1975: Peak deployment (~1,200 aircraft operational across USSR)
  • 1978: Production ends (1,290 total built)
  • 1983: Korean Air Lines Flight 007 shootdown incident (September 1)
  • 1987-1992: Gradual retirement as Su-27 and MiG-31 enter service
  • 1993: Final Su-15 withdrawn from Russian Air Force

Operators

Soviet/Russian PVO (Air Defense Forces): Exclusive operator, deployed at over 50 interceptor bases across USSR

Regional assignments:

  • Moscow Air Defense District (critical capital protection)
  • Arctic bases (countering NATO bomber routes over North Pole)
  • Far East Command (monitoring Pacific approaches)
  • Baltic, Black Sea, Central Asia air defense zones

No exports: Su-15 never sold or transferred to Warsaw Pact/allies due to classified systems

Combat record and incidents

Korean Air Lines Flight 007 (September 1, 1983)

The Su-15's most infamous engagement occurred when Lt. Col. Gennadi Osipovich, flying Su-15TM "805", fired 2 × R-98 missiles at Korean Air Lines Boeing 747 (Flight 007) that strayed into Soviet airspace near Sakhalin Island. All 269 aboard perished. The incident escalated Cold War tensions and remains controversial regarding Soviet rules of engagement and identification procedures.

Other interception activities

1970s-1980s: Thousands of intercepts of NATO reconnaissance aircraft (SR-71, RC-135, Norwegian P-3) probing Soviet airspace

Training accidents: Multiple losses due to high landing speed (300+ km/h) and limited low-speed handling

No air-to-air combat: Su-15 never engaged enemy fighters in war; purely peacetime air defense role

Comparison with contemporaries

vs. MiG-21 "Fishbed": MiG-21 more maneuverable but shorter range and inferior radar; Su-15 optimized for high-altitude bomber interception vs. MiG-21's dogfighting

vs. MiG-25 "Foxbat": MiG-25 faster (Mach 2.83) with better altitude performance but similar limitations (no gun, poor maneuverability, heavy); both specialized interceptors

vs. F-106 Delta Dart (USA): Similar concept (delta-wing, missile-only interceptor, GCI-dependent); F-106 had superior fire control system but comparable performance

vs. English Electric Lightning (UK): Lightning more agile, had guns, but shorter range; both Mach 2+ delta designs

Legacy

The Su-15 represented the apex of Soviet single-mission interceptor philosophy: high-speed, high-altitude specialists optimized for bomber destruction. While effective in its narrow role, changing threat environments (low-altitude cruise missiles, stealth aircraft) and the Su-27's multi-role flexibility rendered dedicated interceptors obsolete.

The KAL 007 incident damaged the Su-15's reputation, highlighting inadequate IFF procedures and rigid rules of engagement. Modern air defense doctrine emphasizes positive identification before engagement—a lesson learned partly through Su-15 incidents.

The type's retirement coincided with the Soviet Union's collapse, with no surviving examples in operational service anywhere by 1993.

Related equipment

Related sections

Technical glossary

Ground-controlled intercept (GCI) : Air defense tactic where ground-based radar controllers vector interceptors onto targets via radio guidance

Delta wing : Triangular wing planform with swept leading edge and straight trailing edge, favoring high-speed flight

SARH (Semi-Active Radar Homing) : Missile guidance requiring launch aircraft to illuminate target with radar until impact

PVO (Protivovozdushnaya Oborona) : Soviet Air Defense Forces, separate branch from tactical air force (VVS)

Look-down/shoot-down : Radar capability to detect and engage low-altitude targets against ground clutter background