The Mikoyan and Gurevich (MiG) 21, code-named 'Fishbed', has been the longest-serving aircraft in the Indian Air Force’s current fleet. The supersonic interceptor has aided the nation in several battles, right from the time it was inducted in 1963.
Despite the fact that modern avionics and armaments were added to the MiG-21 in the Bison upgrade (2001 onward), the airframe is still decades old and cannot be upgraded endlessly.
Hundreds of accidents over the years, including the recent crash of a trainer aircraft in Rajasthan, have fueled debate over the safety of the aircraft and has earned it the infamous 'flying coffin' moniker.
While the root causes of the crashes are difficult to ascertain with the data available in public, it is becoming increasingly apparent that the MiG-21 is a product of its time.
As defence analyst Angad Singh points out, “Now we have only four squadrons of the MIG-21, which is proportional compared to our other aircraft, and still, it’s the MIG-21s that are crashing.”
What's Causing the Crashes?
There have been six MiG-21 crashes since January 2021, in which five pilots have lost their lives. According to data from the Ministry of Defence, over 400 MiG-21s have crashed in the last 60 years, killing over 170 pilots. Media reports peg casualties at over 200.
Notably, the crash rates have fallen since the late 1990s when there were as many as 13 crashes in a year. Post-2003, there have never been more than four crashes in a year, save for 2011 and 2021.
The MiG-21 Bison
(Photo Courtesy: Sandeep Suresh)
Despite all the potential issues that come with the MiG-21's age and design, it is difficult to pinpoint a single reason behind these crashes, partly because there's barely any data available.
"The 'holes in the cheese' have to align. If there are a number of factors that wouldn’t cause an accident in isolation, they can come together to cause one. These can be analysed only when you have the full data."K P Sanjeev Kumar, Ex-navy pilot
Every time a crash occurs, the air force conducts a court of enquiry to get to the root cause of the matter. The results of these investigations, however, aren't made public.
"To really know the truth, you need accident rates vis-a-vis material failure and pilot error. This information will be there in the records, and this question can easily be asked in the Parliament, but nobody has," Vijainder K Thakur, an ex-IAF fighter pilot told The Quint.
Ex-navy experimental test pilot K P Sanjeev Kumar, however, argued that even more detailed information should be made available for public scrutiny.
"It's convenient to normalise accidents by saying we have large numbers of these planes and that’s why there are more accidents. It’s not necessarily true. Sitting outside the system, we are getting cherry-picked figures. We need to see metrics beyond that," he said.
"What stops us from releasing a tranche of accurate investigation reports from the eighties? What harm will that do? I can understand that we don’t want to let go data from the last twenty years, but even the US government declassifies CIA files after some time," he added.
A Soviet-Era Design
While the MiG-21 has been upgraded over time with better avionics and armaments, and even some design features, the airframe of the MiG-21 is still a 50-year-old, Soviet-era design.
The lightweight fighter jet was designed to achieve Mach II, despite its low afterburning turbojet engine.
Currently, only the MiG-21 Bison, which is the most upgraded version of the aircraft, is operational in the air force's fleet. All other variants have been phased out. The Bison has been retrofitted with fourth-generation avionics.
However, the MiG-21 is largely devoid of fly-by-wire technology, which lets onboard computers handle several components of the aircraft, aiding the pilot in several ways, especially in adverse situations.
The MiG-21 Bis of the Indian Air Force.
(Photo Courtesy: Sandeep Suresh)
The MiG-21 was originally designed for high-speed (supersonic) interception of bombers in the post-World War II era, when aircraft designers were chasing sheer speed and power to obtain air superiority.
The IAF, however, has used the MiG-21 in a variety of roles, from high-speed interceptions to low-level dogfighting and close support role. Close support roles are already a hazardous role to carry out.
Moreover, contemporary aircrafts are not competing to see who is the fastest in the sky. Designers have sacrificed speed to make way for better avionics, safety features, and armaments for better air superiority.
'Alpha Sensitive'
Prodyut Das, an aviation analyst and former professor at IIT Kanpur, has written that the MiG-21 was switched to a close support role from the 1980s. Upgrades for the same were made which led to an increase in weight.
This made the aircraft more sluggish and unwieldy during landing and take-off because the aerodynamic control forces decline but the inertia remains the same.
It must be noted here that the MiG-21 already has a higher landing and take-off speed compared to most other aircrafts in the IAF fleet. Its take-off speed is almost double compared to that of other aircrafts. In the event of any fault, the pilot has less reaction time in a MiG-21 as compared to the situation in other aircrafts.
MiG-21 Bisons in action
(Photo Courtesy: Sandeep Suresh)
The MiG-21 also has a very high wing-to-body aspect ratio, making the aircraft “alpha sensitive." This means that the pilot must get the angle of attack just right, else there will be a significant increase in drag without any increase in lift – a state of ‘deep stall.'
During take-off, this means that if the angle of attack is not right, the aircraft can overshoot the runway without lifting off.
Das added that during landing, if the nose is not in the right angle of attack, then the aircraft can slow down drastically and hit the ground before reaching the touchdown area.
What makes the situation worse is that there is no indication from the aircraft like a severe shudder or wing-rocking, to alert the pilot that the plane is in a tricky situation and that the angle of attack needs to be changed. Several modern aircraft have technology to mitigate this and alert the pilot.
Harsh Climates and Bird Strikes
A quick dive into the statistics show that accident rates of single-engine aircraft have always been higher across the world. Most fighter jets of the same era as the MiG-21, including the Starfighter, have had a high crash rate, but the MiG-21 is the only one that remains in service.
Wing Commander Kukke Srikantasastry Suresh, in his blog, noted that India has one of the harshest climates in the world, which makes operating any fighter aircraft a daunting task.
Harsh climate conditions like extreme heat can lead to a 12 percent reduction in thrust and lift, according to Das. Old aircraft like the MiG-21 were not designed to withstand such harsh climate conditions, he added.
The MiG-21 Bison
(Photo Courtesy: Sandeep Suresh)
Bird strikes are also prevalent in India, which is particularly troubling for single-engine aircraft. In double-engine aircrafts, if one engine is lost in the event of a bird strike, the other engine can hold the plane stable until the affected engine is restarted.
Suresh has written that a bird strike leads to surge, stagnation of engine, and flameout depending on the phase of the flight. If it is during take-off or landing, then the pilot may not have enough time to eject.
Newer single-engine aircrafts like the Mirage 2000 (the only other single-engine fighter aircraft in the IAF's fleet) have a set of static-guide panes which reduces the vulnerability to a bird strike. The Mirage also has two air intakes, while the MiG-21 has just one.
The MiG-21 radar system is also limited in capability. The other aircraft in the IAF’s fleet have more advanced radar systems which can aid pilots better in adverse weather and terrain conditions.
However, it must also be noted that several mechanical problems on the MiG-21 had been corrected as they were learnt over time. The experience of the engineers having worked on the aircraft for over 40 years have given them invaluable lessons on what to fix and improve. But there is only so much that can be done.
Why Do We Still Use the MiG-21?
Simply put, the Indian Air Force doesn't have much of a choice. Defense procurement is a time-consuming process and indigenous manufacturing is even slower.
For example, the request for information for 126 multi-role combat aircraft (MRCA) was issued in 2001 and the IAF, after a long process of evaluating the contenders, chose the French Dassault Rafale for the job. Over the next several years, negotiations were turbulent and the deal kept getting delayed.
Finally, in 2016, India signed a deal to buy only 36 Rafales from France. All the aircraft were reportedly delivered by July this year.
The HAL Tejas, India's home-grown light combat aircraft, has experienced multiple delays and setbacks in its design and production. Currently, the Indian Air Force only operates 40 Tejas Mk1 aircraft.
Orders have been placed for trainer aircraft and upgraded variants, but only a handful of planes are expected to be delivered by 2024.
To keep the number of squadrons over 30, the IAF has had no choice but to keep the MiG-21 in service. Despite its potential shortcomings, the aircraft continues to be effective in combat. (Retd) Squadron Leader Thakur describes it as "a capable aircraft which has given hell to F-16s."
MiG-21s, however, won't stick around for long. The remaining four squadrons will be phased out in a three-year timeline, which will make it near impossible for the IAF to reach its sanctioned strength of 42 squadrons in the next decade.
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