Overview

The Tupolev Tu-126 (NATO reporting name: "Moss") was the Soviet Union's first operational airborne early warning and control (AEW&C) aircraft. Based on the Tu-114 turboprop airliner, it featured a distinctive rotating radome mounted above the fuselage, providing long-range surveillance to Soviet air defense forces. Only nine production aircraft were built (1965-1971), serving until replacement by the A-50 "Mainstay" in the late 1980s.

Historical context

Soviet military planners recognized the need for airborne radar surveillance after observing U.S. Navy E-1 Tracer operations in the early 1960s. NATO bombers and reconnaissance aircraft could exploit radar coverage gaps by flying low-altitude profiles, evading ground-based early warning systems.

Development began in 1958 based on the Tu-114 long-range airliner (itself derived from the Tu-95 strategic bomber). The Liana ("Liana vine") radar system, developed by VNIIRT research institute, used an 11-meter rotating radome housing S-band surveillance radar. First flight occurred in January 1962 with the prototype Tu-114PL, followed by production Tu-126 entering service in 1965.

Operational experience revealed significant limitations: the radar struggled with look-down capability against low-altitude targets over land, and onboard computing power proved inadequate for complex battle management. Despite shortcomings, the Tu-126 remained the USSR's only AEW platform for two decades.

Specifications

Commonly cited specifications (Tu-126 production standard):

Dimensions:

  • Length: 55.20 m (181 ft 1 in)
  • Wingspan: 51.10 m (167 ft 8 in)
  • Height: 15.50 m (50 ft 10 in) to radome top
  • Wing area: 311.1 m² (3,349 sq ft)
  • Radome diameter: 11.0 m (36 ft 1 in)

Weights:

  • Empty weight: 90,000 kg (198,416 lb)
  • Normal takeoff: 170,000 kg (374,786 lb)
  • Maximum takeoff: 175,000 kg (385,809 lb)

Powerplant:

  • Engines: 4 × Kuznetsov NK-12MV turboprop engines
  • Power: 14,795 shp (11,033 kW) each
  • Propellers: 8-blade contra-rotating AV-60K constant-speed propellers (4.8 m diameter)

Performance:

  • Maximum speed: 850 km/h (528 mph, 459 kn)
  • Cruising speed: 670 km/h (416 mph, 362 kn)
  • Patrol speed: 550 km/h (342 mph) optimal for radar operations
  • Endurance: 12-15 hours on station
  • Service ceiling: 10,000 m (32,808 ft)
  • Patrol altitude: 8,000-9,000 m (26,247-29,528 ft) typical
  • Range: 8,500 km (5,282 mi) ferry range

Crew:

  • Flight crew: 5 (pilot, copilot, navigator, flight engineer, radio operator)
  • Mission crew: 7-12 radar operators and controllers

Sensors:

Liana radar:

  • Type: S-band pulse-Doppler surveillance radar
  • Detection range: 300 km (186 mi) vs. bomber-sized targets at high altitude
  • Look-down range: ~80-100 km (50-62 mi) vs. low-altitude targets over water
  • Tracking capacity: 50-60 targets simultaneous detection, ~10-12 tracked
  • Rotation speed: 10 RPM (6-second scan cycle)

IFF system: Identification Friend or Foe transponder interrogator

Datalink: Secure communication with ground-based PVO command centers and vectored interceptors

Design characteristics

Airframe basis

The Tu-126 inherited the Tu-114's robust airframe:

Swept wings: 35° sweep angle for transonic cruise efficiency

High-mounted wing: Fuselage clearance for large contra-rotating propellers

Pressurized cabin: Maintained sea-level pressure equivalent at operating altitude

Structural reinforcement: Additional bracing around radome mounting points to handle aerodynamic loads and rotation mechanism

Radar system

Rotating radome: 11-meter diameter disk housing planar array antenna

Rotation mechanism: Electric motor turning radome at 10 RPM continuously

Cooling system: Air conditioning for radar electronics and operator stations

Signal processing: Analog computing systems with limited digital integration (1960s technology)

Limitations:

  • Ground clutter rejection: Inadequate Doppler processing caused false targets over land
  • Altitude discrimination: Difficulty distinguishing targets at different altitudes in same azimuth
  • Data transmission: Limited bandwidth to ground stations and interceptors

Mission systems

Battle management consoles: 10-12 operator stations with radar scopes and radio communications

Navigation: Inertial navigation system (INS) with radio navigation backup

Communications: HF/VHF radio suites for ground stations, fighter direction, and command links

Endurance provisions: Galley, rest area, toilet for extended 12+ hour patrols

Operational deployment

Service timeline

  • 1962: First flight of Tu-114PL prototype
  • 1965: Initial operational capability with PVO
  • 1968: Full operational deployment begins
  • 1970: Peak strength (9 aircraft operational)
  • 1970s: Patrols over Baltic, Black Sea, Arctic approaches, Far East
  • 1984: A-50 "Mainstay" replacement begins testing
  • 1987: Gradual retirement as A-50 enters service
  • 1990: Final Tu-126 withdrawn from operational status

Operational units

67th Special Aviation Detachment, Å iauliai Air Base (Lithuania): Primary Tu-126 operator

Missions:

  • Baltic Sea patrols: Monitoring NATO naval aviation and maritime reconnaissance
  • Arctic surveillance: Detection of NATO bomber routes over North Pole
  • Black Sea coverage: Tracking U.S. Navy carrier operations
  • Exercise support: Providing early warning during large-scale Soviet air defense drills

Typical patrol profile:

  1. Takeoff from Å iauliai or forward staging base
  2. Transit to patrol area (1-2 hours)
  3. Racetrack pattern at 8,000-9,000 m for 8-10 hours
  4. Return to base (1-2 hours)

Integration with PVO

Command and control:

  • Tu-126 relayed radar picture to ground-based PVO command posts
  • Ground controllers directed interceptors (Su-15, MiG-23, MiG-25) based on Tu-126 data
  • Limited onboard fighter control capability due to cramped workstations

Doctrine:

  • Extend radar coverage 300+ km beyond ground radar horizon
  • Early warning of NATO maritime strike packages
  • Detection of low-altitude penetrators avoiding ground radar

Strengths and limitations

Advantages

Long endurance: 12-15 hour patrols far exceeded ground radar persistence

Extended range: 300 km radar detection pushed defense perimeter hundreds of kilometers outward

Mobility: Could deploy to forward bases supporting exercises or crisis response

Battle management: Centralized airborne control reduced ground controller workload

Turboprop efficiency: NK-12MV engines provided excellent fuel economy for long patrols

Limitations

Look-down capability: Severe ground clutter over land limited low-altitude detection

Processing power: 1960s analog computers couldn't handle dense target environments

Automation: Required 12+ crew for tasks modern AWACS perform with 6-8

Self-defense: No defensive armament, relied on fighter escort over hostile areas

Availability: Only 9 aircraft meant limited coverage; typically 3-4 operational at any time

Data link bandwidth: Slow data transmission rates (pre-digital technology)

Comparison with contemporaries

vs. E-3 Sentry (USAF): E-3 entered service 1977 with vastly superior APY-1/2 pulse-Doppler radar (360° coverage, 400+ km range, true look-down/shoot-down), digital computers, and 13+ hour endurance—generational advantage over Tu-126

vs. E-2 Hawkeye (USN): Smaller carrier-based AEW, but rotodome design similar to Tu-126; E-2C (1973+) had better radar processing despite smaller size

vs. Hawker Siddeley Nimrod AEW.3 (UK): British attempt at indigenous AWACS, cancelled 1986; similar technology challenges to Tu-126 with look-down radar

Replacement and legacy

The A-50 "Mainstay", based on Il-76 transport, replaced the Tu-126 beginning in 1987. The A-50's Shmel ("Bumblebee") radar offered genuine look-down/shoot-down capability, digital processing, and improved ergonomics.

Tu-126 provided the Soviet military with two decades of operational AEW experience, informing requirements for the A-50 and subsequent A-100 programs. The type demonstrated both the value and challenges of airborne early warning—extending air defense reach while revealing the technological sophistication required for effective battle management.

No Tu-126 aircraft were exported. Several examples are preserved at museums including the Russian Air Force Museum at Monino.

Related equipment

Related sections

Technical glossary

AEW&C (Airborne Early Warning and Control) : Aircraft equipped with radar surveillance and battle management systems for air defense coordination

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

Radome (radar dome) : Protective housing for radar antenna, transparent to radio frequencies

Pulse-Doppler radar : System using Doppler shift of radar returns to distinguish moving targets from stationary background clutter

Turboprop : Turbine engine driving propeller through reduction gearbox, combining jet efficiency with propeller thrust at lower speeds