Tejas 'Made in India'? HAL veteran breaks down the truth

The Federal spoke to D Raghunandan, aerospace and defence expert with the Delhi Science Forum and former Hindustan Aeronautics Limited (HAL) engineer, on what the Tejas crash at the Dubai Air Show suggests about the aircraft, India’s dependence on foreign engines, and how much we can really know from air crash investigations.

What are your initial thoughts on the Tejas crash in Dubai?

My first reaction is that we still do not know enough. All we have are comments from a few pilots and experts, and some short video clips of the crash.

From what I have seen, it appears that the aircraft was not under the control of the pilot when it went down. Whatever happened during the zero-G and negative-G manoeuvres, it looks to me as if, even if the aircraft had stalled, it was unable to recover from that state.

I would normally expect to see some visible effort by the pilot to recover from the dive. In the video, the aircraft seems to go straight down. That is why my sense is that the pilot may have blacked out. The aircraft was already flying quite low, so if he blacked out, there would have been no effective control.

The aircraft looks under power as it goes down, which again suggests the controls were not being actively flown. If the pilot had been conscious and aware, he would at least have had time to eject. My initial thought is that he blacked out because of the negative-G manoeuvre, and the aircraft, already at low altitude and out of control, simply went down.

If there was a systems failure, how do you see Tejas’s dependence on foreign suppliers for engines and avionics, and where does accountability lie?

At this stage, I would not jump to the conclusion of a systems failure. As far as the Tejas is concerned, this particular model has about 60% indigenous content. Major components like the engine are foreign-origin, but the integration is done by HAL, and I must add, under the supervision of the Indian Air Force (IAF).

The history of Tejas has involved an uneasy relationship between three key players: the Air Force as the user, the Defence Research and Development Organisation (DRDO) as the designer, and HAL as the manufacturer. It has been a triangular push-and-pull, especially in the early stages. Each was somewhat suspicious of whether the others were doing their job properly.

The IAF, as the user, has taken a very proactive role in both design and manufacture. Because of that, I think one can be reasonably sure that the Air Force would not have allowed a mismatched aircraft into service — for example, with avionics misfiring or the engine behaving unpredictably. They would not have certified such an aircraft or gone ahead with induction unless they were satisfied on all counts.

Tejas has had a largely trouble-free flight history since its first flight in 2001. It has flown for about 24 years now with no crashes until last year’s incident in the Jaisalmer region, and now this one. We still do not know enough about what happened in Jaisalmer.

Even in this Dubai case, if there was a loss of control or an inability to recover from the manoeuvre, that is not unique to Tejas. These kinds of aerobatic manoeuvres are tricky even for the best aircraft. Accidents can happen. Pilots can black out, even though they are trained to withstand negative-G conditions.

Eyewitnesses have said the pilot was executing a loop, with the dive ending in a roll. A low-altitude roll coming out of a dive is a very difficult manoeuvre, and the chances of losing control are relatively high. So, at this stage, I would not ascribe fault to the aircraft. This could happen to some of the best aircraft anywhere.

Globally there have been incidents where flight control systems misread conditions, like the F-35 case. How does altitude play into what happened with Tejas?

You are right to bring up the F-35 incident where the landing gear logic and flight control system misread the aircraft’s state and caused problems. In that case, the pilot had enough altitude to diagnose the issue, talk to maintenance, and eventually eject safely.

Altitude is critical. In aerobatic manoeuvres like the one we saw at Dubai, you are stressing flight control systems because you are switching rapidly between conditions: one moment you are diving, the next you are climbing, then rolling. Modern fighters are designed for such transitions — in a dogfight you do not fly smooth, gentle arcs — but the systems are under stress.

Flight control systems can be vulnerable. They can respond incorrectly to unexpected combinations of inputs. That is rare, but as you mentioned with the F-35, it can happen and sometimes leads to software changes.

Tejas has been put through these manoeuvres at air shows for many years, including Dubai, without issues. So again, I would treat what happened as one of those rare events that occasionally occur in high-performance flying, rather than immediately assuming an inherent design problem. At this point, we do not have evidence to say that flight control malfunction caused this particular crash.

Why has India still not developed its own reliable fighter jet engine after decades of work? What makes engines such a bottleneck?

Within aviation, I am more of an aero-engine person than an airframe person, so this is an area I know closely.

There is a common phrase: “It’s not rocket science,” meaning something is not that complex. In my view, an aero engine is actually more complex than a rocket engine. If you really want a comparison of difficulty, you should say “It’s not an aero engine.” It is one of the most complex engineering structures we deal with.

There are several reasons. First, the sheer number of moving parts in an aero engine. All of them have to work together smoothly, especially in fighters that need rapid changes in thrust, speed, and attitude. The engine must deliver smooth power through all this, without causing stalls or loss of control.

Second, the internal architecture: you have a compressor that builds pressure, a combustion chamber where fuel is mixed and burned, and then a turbine which extracts power from gases at very high temperatures — often around 1,800°C — before they are exhausted to produce thrust.

The “hot section” — combustion and turbine — is especially demanding. It is not just aerodynamics and gas flow; it is also materials science. You need materials that can withstand those extreme temperatures and stresses, over long periods, under rapid changes in operating conditions.

Modern fighter engines use extremely sophisticated turbine blades. They are delicate, aerodynamically shaped, like tiny wings, and the airflow over them has to be precisely controlled. At the same time, they operate at temperatures and rotational speeds where microscopic flaws can grow into cracks. If a turbine blade cracks and fails, it can catastrophically damage the engine and bring the aircraft down.

That is why the engineering of the hot section, especially the turbine blades, is one of the toughest jobs in modern aerospace. You now have advanced technologies like single-crystal turbine blades, where each blade is grown as a single crystal of metal to maximise strength and temperature resistance.

Now, how does this make it hard for HAL or India to make our own engine? If we import a General Electric F414 or a Safran engine and build it here under collaboration, they can teach us how to manufacture it. But that does not automatically teach us how to design a new engine from scratch. Design knowledge is a different level of know-how, much harder to transfer.

If you look globally, only four or five countries have truly mastered designing and producing modern fighter engines on their own. Many countries make aircraft, but very few make engines. Even China, which produces advanced fighters, is in my view still catching up on engine technology, particularly in achieving the reliability and performance levels of the US, France, Russia or the UK.

So, India is not unique in struggling with engines. It is the hardest part. You can build the fighter airframe and many subsystems, but the engine remains the toughest nut to crack.

What India is now trying to do is enter collaborations that can help us shorten the learning curve, so that next time we can do much more ourselves. We could attempt a fully indigenous engine again, but that might take 20 years or more. Realistically, no one has the appetite for that long a timeline right now. So, it is better to get help, learn the deeper tricks, and then move towards an indigenous next-generation engine.

You also tracked the recent Air India crash. The preliminary report shows engines of different ages and hours. Is that normal, or a red flag?

In the Air India case, the Aircraft Accident Investigation Bureau (AAIB) report shows, for example, that one engine was built in May 2012 and the other in January 2013. One had around 27,791 hours, the other about 33,439 hours.

To me, that is not surprising at all. Engines go through regular cycles of repair and overhaul. Suppose I have a brand-new twin-engine aircraft. When it goes in for overhaul, both engines are removed and sent to workshops. I may have engines in the airline’s inventory that I mount on the aircraft while the original engines are being worked on.

Those “replacement” engines may have very different life histories — different hours flown, different dates of manufacture. I am not likely to have two spare engines sitting with exactly the same hours. In a large fleet, as you rotate engines in and out for overhaul, you almost always end up with mismatched ages and hours on a given aircraft.

The critical issue is not that the engines are of different ages, but whether each engine individually meets airworthiness standards after overhaul and inspection. If those checks are done properly and the engines are certified, having different hours on the two sides is not, by itself, a cause for alarm.

The overall health of an engine depends on many factors: operating conditions, maintenance history, environmental exposure, not just the raw hours. So I would not draw conclusions simply from the difference in hours, nor would I treat it as automatic evidence of a fault in something like the electronic engine control.

In both the Air India crash and the Tejas incident, pilots did not survive. In Tejas, the pilot had an ejection seat. Why might he not have ejected?

I do not think his failure to eject is linked to any failure of the ejection system itself. Tejas uses a well-proven ejection seat, supplied by a specialist manufacturer.

The fact that he did not eject reinforces my earlier suspicion: he may not have been fully conscious at the crucial moment. If a pilot is conscious, aware that the aircraft is unrecoverable, and has even a few seconds, standard training would lead him to eject.

My feeling is that he blacked out during the manoeuvre and may have remained semi-conscious or disoriented as the aircraft descended. By the time he was recovering his bearings — if he was recovering at all — the aircraft was simply too low for him to respond or eject.

So, the absence of an ejection, in this context, is more consistent with a pilot incapacitation scenario than with a systems failure.

Crash investigations often depend on data from foreign manufacturers. Does this limit India’s ability to uncover the truth?

In civilian crashes like the Air India case, yes, there is a concern. The parties involved include manufacturers like Boeing for the aircraft and GE for the engines. They are powerful foreign entities, and they can influence the flow of information.

They can pressure the Indian government directly, asking it not to “rock the boat” in terms of business and bilateral relations. They can influence the regulator, the Directorate General of Civil Aviation (DGCA). They are also parties to the investigation, which can give them leverage over what data is shared and how quickly.

So in civilian aviation, there is definitely a risk that uncomfortable facts can get diluted or delayed, especially if they reflect badly on big foreign manufacturers.

In the Tejas case, the situation is different. The primary stakeholder is the Indian Air Force, because its personnel fly the aircraft and their lives are at stake. If there is any problem with the aircraft or its systems, the Air Force will want to know.

They are not going to benefit from hushing things up. Even if the government tells them to “go easy” in public, internally, between the IAF, DRDO and HAL, the truth will be pursued very aggressively. They may choose not to share everything with the public or media, but among themselves, there will be no incentive to hide a real problem, because that would endanger their own pilots.

So I am far less worried about secrecy and brushing things under the carpet in the Tejas probe than in a civilian Air India-type case. In military aviation, the internal pressure to get to the bottom of the issue is much stronger.

Given all this, should India push for fully indigenous avionics and systems on its fighters for strategic reasons?

On avionics, I have a fair amount of confidence in what India has already achieved and deployed, particularly on military aircraft.

We have carried out upgrades of MiGs, Jaguars and Mirage-2000s using Indian avionics. In fact, in the Mirage upgrade, there was a real struggle to get the French to accept Indian avionics being integrated into their platform. They would have preferred us to continue with their systems, but India insisted on using its own.

We have similar tussles with Russian suppliers, and still have debates with Dassault Aviation over Rafale systems: which controls can be Indian, which must be theirs, and who takes responsibility for what. Dassault’s position is often that they will only take responsibility if their components are used in that chain.

Despite these challenges, Indian avionics have been integrated and proven on multiple platforms. Given the long and sometimes tortuous development path of Tejas, I would say the process has also built a robust level of confidence among stakeholders — the Air Force, DRDO and HAL — about the performance and integration of these systems.

So I am reasonably sure the avionics part is sound. Ultimately, the black boxes — flight data recorder and cockpit voice recorder — will tell us much more. Once they are recovered and analysed, we will get a clearer picture of what the flight control systems were doing, how the aircraft was responding, and possibly what condition the pilot was in.

That data will be crucial in answering many of the questions that, right now, we can only speculate about.

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