From MiG-21 to Tejas: Where India’s Fighter Replacement Stands

From Imported to Indigenous series · File 4 · Sarp Güçlü

On 26 September 2025, the Indian Air Force retired the last of its MiG-21s after 62 years of service. The jet meant to replace it, the indigenous HAL Tejas Mk1A, was not there to meet it: engine supply problems have pushed the programme nearly two years behind its own schedule. What exists today is a retirement and an incomplete handover, not yet a completed swap.

What was the old system?

The MiG-21, designed by the Soviet Mikoyan-Gurevich bureau, became the most-produced supersonic jet fighter in history. India received its first examples in 1963, equipping No. 28 Squadron “First Supersonics” — the IAF’s first supersonic type. Under the 1961 procurement deal, the Soviet Union also transferred production technology and local-assembly rights; Hindustan Aeronautics Limited (HAL) built airframes at Nasik, avionics at Hyderabad, and engines at Koraput with Soviet assistance. HAL’s licensed output across the MiG-21FL, MiG-21M and MiG-21bis variants totalled 657 aircraft (The Tribune); combined with imported airframes, total IAF holdings are cited anywhere from 840 to 870 depending on the source — no single, consistent official tally is public. A large share of the fleet was upgraded to the “Bison” standard in the 2000s with the Israeli-derived Kopyo radar and R-77/R-73 missiles. The last Bisons flew their farewell at Chandigarh on 26 September 2025, with No. 23 Squadron “Panthers” among the final operators (Scroll.in).

Why did India need an indigenous replacement?

Three separate pressures converged. First, age: a 1960s-vintage design whose accident record was repeatedly debated in public and fed demands for early retirement. Second, strategic dependence: the fleet relied on a single foreign supply chain — first Soviet, then Russian — for spares and technical support. Third, industrial policy: since the 1980s, successive Indian governments have pushed to cut defence import dependence. Defence Minister Rajnath Singh, unveiling the first production Tejas Mk1A at HAL’s Nashik facility in October 2025, said defence equipment imports stood at 65–70 percent before 2014 and that roughly 65 percent of equipment is now domestically made (Prasar Bharati / News on Air). Official statements do not cite a formal embargo; the stated rationale is supply security and industrial capability.

How was the indigenous jet developed?

The Tejas programme traces to 1983, when the government sanctioned the project-definition phase of the Light Combat Aircraft. The Aeronautical Development Agency (ADA) was created under DRDO to run it. Development slipped by well over a decade: the first technology demonstrator (TD-1) flew on 4 January 2001, the name “Tejas” was adopted in 2003, and the first limited-series production aircraft flew on 25 April 2007. Operational deliveries to the IAF began on 17 January 2015; in July 2016, No. 45 Squadron “Flying Daggers” became the first unit to swap MiG-21s for Tejas Mk1, followed by No. 18 Squadron “Flying Bullets”. Final Operational Clearance followed in January 2019. For the upgraded Mk1A, the IAF signed its first large production contract for 83 aircraft (roughly ₹48,000 crore) in January 2021; a second contract for 97 aircraft (₹62,370 crore, 68 single-seat and 29 twin-seat) followed on 25 September 2025, bringing total orders to 180 (Deccan Herald). The first Mk1A off the new production line was unveiled at Nashik on 17 October 2025. India’s own indigenous-engine effort, the Kaveri project, never reached the thrust and reliability levels needed for a fighter application, leaving Tejas dependent on GE engines from the outset.

How much of it is actually indigenous?

Engine: Foreign. The GE Aerospace F404-IN20 (USA) is used; the first of 99 contracted engines was delivered in March 2025, roughly two years behind schedule.
Radar: Mixed. The first 83 Mk1A jets use Israel’s EL/M-2052 AESA as an interim fit; DRDO’s indigenous Uttam AESA is targeted for most of the second 97-aircraft batch from 2027, but is not yet in series production.
Electronic warfare: Indigenous. The Unified EW Suite was developed by India’s Defence Avionics Research Establishment (DARE).
Weapons: Mixed. The indigenous Astra Mk1 and Israel’s I-Derby ER both cover beyond-visual-range engagement; short range relies on Russia’s R-73, with Israel’s Python-5 integration still in progress.
Production: In India (HAL’s Nashik and Bangalore lines), though key subsystems — the engine and parts of the radar/avionics suite — remain imported.
Design: Indigenous, led by ADA/DRDO; the airframe aerodynamics and quadruplex digital fly-by-wire software were developed in India.

Official figures do not fully agree: the Ministry of Defence cites “over 64 percent” indigenous content for the 97-jet batch, while Mk1 content was put at 59.7 percent by value and 75.5 percent by line-replaceable-unit count as of 2022 — the two measures use different bases and are not directly comparable. With the engine still foreign, “fully indigenous” is not an accurate description of this platform.

Has it really replaced the MiG-21?

It is being phased in gradually. Tejas began replacing MiG-21s squadron by squadron from 2016, through No. 45 and No. 18 Squadrons. But the remaining MiG-21 Bison units — No. 3 “Cobras” and No. 23 “Panthers” — were retired outright on 26 September 2025, before Mk1A deliveries had reached serial volume. The result: squadron strength sits at 29 against a sanctioned 42 (Army Recognition). The Ministry’s September 2025 contract for 97 jets sets deliveries from September 2027 through September 2033; the first production-line aircraft was unveiled in October 2025, but a confirmed, numbered handover to IAF squadrons could not be verified against public sources as of this writing. The replacement decision stands and the programme is moving, but the gap the MiG-21 left behind has not yet closed.

How does this compare elsewhere?

Similar “import-then-indigenous” fighter transitions are under way elsewhere: South Korea’s KF-21 Boramae is meant to replace ageing F-5/F-4 fleets, Pakistan turned to co-production with China for the JF-17 Thunder, and Türkiye is developing KAAN to eventually replace its F-16 fleet — all three still depend on foreign engines (see KAAN and AMCA: Two Industrial Architectures for the Same Goal, envantermedya, 27 October 2026). Earlier files in this series on Türkiye’s ALTAY (South Korean-origin powerpack) and Poland’s PIORUN (Soviet-derived design lineage) point to the same pattern: engine or power-unit dependence is the most common weak point in platforms declared “indigenous.”

Strategic and industrial outcome

The Tejas programme gave HAL real capability it did not have before 1983: composite airframe manufacturing, quadruplex digital fly-by-wire software, and a serial production line. But continued engine dependence limits any claim of full independence, and HAL’s own target of raising output to 16 aircraft a year is widely described in trade coverage as ambitious given the programme’s delivery record. Export talks with Malaysia, Argentina and Egypt remain open, but no finalised export contract exists to date. Until the squadron gap closes, the IAF is covering the shortfall by loading extra duty onto its Mirage 2000, Su-30MKI and Rafale fleets — underscoring that the technology gain is real even as fielded readiness still lags behind it.

FAQ

Sources

Primary
Prasar Bharati / News on Air — Defence Minister unveils first Tejas Mk1A, 17 October 2025
Deccan Herald, reporting the Ministry of Defence’s 97-jet contract, 25 September 2025
The Week, reporting GE Aerospace’s first F404-IN20 engine delivery, 26 March 2025

Independent
Army Recognition — Tejas Mk1A’s first flight and the start of the MiG-21 replacement
The Tribune — MiG-21’s 60-year history in India
Scroll.in — MiG-21’s retirement after 62 years

Envantermedya archive
From M60 and Leopard to ALTAY: Türkiye’s National Tank Transition
From Strela-2/Igla to PIORUN: Poland’s MANPADS Transition
From Harpoon to ATMACA: Türkiye’s Naval Missile Transition
KAAN and AMCA: Two Industrial Architectures for the Same Goal