Military Flight Safety

[sohamn]

There is something strange about this incident
a) Drop tanks are still there
b) Landing gears are down
c) Plane is flying level

If an aircraft is under distress, the first things that a pilot is trained to do is to reduce drag and lighten load to make sure it can glide for a long distance. In this case, the pilot hasn't attempted to do any of that. Very strange outcome.

[nachiket]

There is something strange about this incident
a) Drop tanks are still there
b) Landing gears are down
c) Plane is flying level

If an aircraft is under distress, the first things that a pilot is trained to do is to reduce drag and lighten load to make sure it can glide for a long distance. In this case, the pilot hasn't attempted to do any of that. Very strange outcome.

Dropping tanks over inhabited terrain would be very dangerous. Landing gears are down because the aircraft was on approach for landing. If you have an engine failure during approach the landing gear should stay out because it absorbs some of the impact during a crash landing. Plane flying level means the flight control system still had backup power though the engine had failed. It was impossible to relight the engine at that low an altitude so the pilot had to eject.

Unfortunately fighter aircraft don't glide very well so the rate of descent would have been too much for the pilot to survive landing without power short of the runway. Ejection was the only option.

[Rakesh]

Ananthakrishnan says the tail number is LA-5020. See the currently live stream.

Thank You. i will update Page 1 of the HAL Tejas Mk1 thread.

Added Later: Page 1 updated ---> viewtopic.php?t=7878

Created a new accidents sub-heading, right below the squadron strength of No18 Flying Bullets.

[sohamn]

There is something strange about this incident
a) Drop tanks are still there
b) Landing gears are down
c) Plane is flying level

If an aircraft is under distress, the first things that a pilot is trained to do is to reduce drag and lighten load to make sure it can glide for a long distance. In this case, the pilot hasn't attempted to do any of that. Very strange outcome.

Dropping tanks over inhabited terrain would be very dangerous. Landing gears are down because the aircraft was on approach for landing. If you have an engine failure during approach the landing gear should stay out because it absorbs some of the impact during a crash landing. Plane flying level means the flight control system still had backup power though the engine had failed. It was impossible to relight the engine at that low an altitude so the pilot had to eject.

Unfortunately fighter aircraft don't glide very well so the rate of descent would have been too much for the pilot to survive landing without power short of the runway. Ejection was the only option.

Few points as rebuttal

a) I don't understand why drop tanks in inhabited areas are dangerous. Or did you mean habited? In either case, dropping tanks is less dangerous than crashing the aircraft on a house with drop tanks intact.
b) When you are out of power, you don't get landing gears down until the very last moment and if you are landing in a field, sand or lake then its better to land belly up.
c) Delta wing has a lot of lift and it should glide better than a conventional fighter as long as flight controls are working.

I hope we know the cause of the incident soon.

[basant]

Antonym of inhabited is uninhabited, not habited! We do not know at what stage the engine failed and the status of the landing gear at that stage. The crash site is about 2.5-3.0 km from the airport and I guess that the pilot would not have had much reaction time (2-3 min?) and minimum recovery height for engine restart. Delta wings perform better in supersonic regimes and not in subsonic regime where they produce more lift but also higher drag.

[nachiket]

Few points as rebuttal

a) I don't understand why drop tanks in inhabited areas are dangerous. Or did you mean habited? In either case, dropping tanks is less dangerous than crashing the aircraft on a house with drop tanks intact.
b) When you are out of power, you don't get landing gears down until the very last moment and if you are landing in a field, sand or lake then its better to land belly up.
c) Delta wing has a lot of lift and it should glide better than a conventional fighter as long as flight controls are working.

I hope we know the cause of the incident soon.

a) Inhabited = populated. Uninhabited = unpopulated. If you know you can't make it to the runway even if you drop tanks then if you drop then you might take out one or two houses with the tanks and another one with the aircraft itself.
b)Engine might have failed after the gears were down. On water, belly landing will be preferred. But why on land?
c)I meant the glide ratio won't be as good as say an airliner. Pilots can do glide calculations for their aircraft in their heads. So before ejecting the pilot must have calculated that reaching the runway was impossible with the given airspeed, altitude and distance remaining to the runway.

[Haridas]

Genuinely curious: why do an AVM and a squadron leader feel the need to fly a trainer such as Kiran?

The AVM seems to be ETP (E? TEST PILOT) and the Squadron Leader (https://www.google.com/amp/s/www.hindus ... 4-amp.html) seems to be an FTE (Flight Test Engineer), so both were probably on some kind of evaluation test flight.

This called check flight, it is mandatory after a pilot has not flown for more than certain period of time. Flying sole (or as captain in the type rate aircraft is necessary to maintain pilots flying rating. This is SOP for all command / senior officers so they can retain their rating and flying pay. {specially important for retirement pay baseline}.

[Haridas]

There is something strange about this incident
a) Drop tanks are still there
b) Landing gears are down
c) Plane is flying level

If an aircraft is under distress, the first things that a pilot is trained to do is to reduce drag and lighten load to make sure it can glide for a long distance. In this case, the pilot hasn't attempted to do any of that. Very strange outcome.

The plane was just few seconds from crash, how much more your wanted the pilot to glide? (down to last 10 meters !!) The pilot eject after having exhausted all options within available altitude/time to crash.

Single engine aircraft pilots have to memeorize the emergency checklist by heart. When crisis hits, all checklist have to run mentally to recover.

In this case clearly pilot had lowered undercairrage in hope of fortuitously finding a flat area to land. Finding none and critically low on altitude, he did the best thing -- eject.

Yes the fighter plane is flying as a unpowered stone glider (the wing aspect ratio is so low for fighter) ; making it fly high AoA makes glide-ratio worse.

Its flying level because of its very good flight control computer.

IMVHO from available data this crash is due to engine power loss due to intrinsic engine failure or bird-hit.

[Haridas]

^^ I had the misfortune of watching with my eyes a IAF Mirgae2000 crash few hundred yards away (piloted by the CO). And I am from IAF family.

[sohamn]

b)Engine might have failed after the gears were down. On water, belly landing will be preferred. But why on land?

Because landing gears perform very poorly in anything except for paved roads, they dig into to soil, collapse inwards and create massive structural compromise which can cause aircraft to disintegrate on landing. When your plane is a glider, never deploy landing gear ever unless you are sure you are making it to the airport or a proper road.

The checklist is to
a) reduce drag,
b) reduce weight,
c) trim for Vg or best glide speed
d) declare emergency, location, souls onboard, fuel onboard & intent
e) if time permits attempt to relight engine ( turn on fuel pumps, see if engine is windmilling, fuel flow is on, use starter if required )
f) if nothing works point the plane towards an empty field and eject

[Pratyush]

The pilot is the best Judge of the situation in the cockpit. It is unwise to second guess his choices on the basis of only a fragment of information.

I would suggest that posters wait for the court of enquiry finish it's job. Before we argue about the pilots choices.

[Manish_P]

Agree with the sentiment.

The CoI findings are usually not made public though, are they (due to sensitive info)? At least not till a few years have passed.

Informed discussion by experienced posters helps newbies like me get a sense on the possible causes/effects.

[sajaym]

And at this point...since this a domestically produced fighter... we have to ask the important question - How long will it take to replace the destroyed fighter with a brand new one?

[Haridas]

^^ why cry over split milk?

Charge forward with all you have is the motto.
PM Modi is now directly reviewing Tejas production; I hope few examplary dismissal of top guys who fail promised delivery.

[SidSom]

PM Modi is now directly reviewing Tejas production;

The Conspiracy theorist in me stares at this statement and ponders on the timing of the crash.......

[Manish_P]

And at this point...since this a domestically produced fighter... we have to ask the important question - How long will it take to replace the destroyed fighter with a brand new one?

+1 Absolutely

The critical momentum is there.. it won't be stopped now. It would have been a real big worry (for the program itself) if a crash had happened before induction.

The usual suspects are quiet. They know hard questions (about crashes of imported birds) will be asked if they try to peddle their agenda.

In fact some knowledgeable handles have gone on the offensive - preemptively pointing to crashes of the F22, F35, B2,..... the space shuttle.

These really are different times from just a decade ago.

Aagey badho, Udtey raho.

[srai]

And at this point...since this a domestically produced fighter... we have to ask the important question - How long will it take to replace the destroyed fighter with a brand new one?

The Indian procurement process is a lengthy one (13 steps) even for IDDM.

[Jay]

This is a day/event we all have dreaded since January 04, 2001. The dread is not only because of the lives that will be directly impacted by such a crash, but also because of how this event might be portrayed and used to kill the program itself. But 24 years later, after so much toil by all the dedicated folks who made it possible to what Tejas is today, it feels like we have reached a mental milestone where we look at this dispassionately and not beat ourselves with self-doubt and pity. I cannot think of another single engine fighter that sustained its development and deployment program for this long and without losing a single bird or soul. I feel incredibly proud of this achievement.

Best wishes and a speedy recovery to the pilot.

[Prem Kumar]

X/Twitter Desi Defense brigade is a savage bunch (& that's a good thing!)

So much so that Import Bahadur veterans often fear to engage, because they are afraid of being exposed

I am pleasantly surprised by the relatively mute response to the crash. The home-team was getting their arsenal ready

[Manish_P]

...

I am pleasantly surprised by the relatively mute response to the crash....

+1

No shrill rona-dhona by the presstitues. The propoganda peddlers are more careful now as the aam janta is more informed due to social media (thanks to knowledgeable jingos) and won't hesitate to call them out.

Meanwhile the cool, calm professionals actually connected with the projects quietly keep moving forward towards getting the job done.

[Cyrano]

Yes, the immediate spread of videos on SM prevented useless heehaw.

The pilot ejected and survived, seemed lucid and visibly ok when the local janta came to his aid. The plane was seen flying level with landing gear down.

No chance for anyone to insinuate.

Let's wait for the CoI report.

[Manish_P]

... The plane was seen flying level with landing gear down.

No chance for anyone to insinuate.
.....

A testament to the desi developed FCS .. and it shifted the spotlight to the engine - which is a proven reliable one made in the US of A no less.

[chetak]

... The plane was seen flying level with landing gear down.

No chance for anyone to insinuate.
.....

A testament to the desi developed FCS .. and it shifted the spotlight to the engine - which is a proven reliable one made in the US of A no less.

Manish ji,

Generally speaking, if it was the engine, then it means no power for the FCS, which leaves only the battery option that is very limited time wise

Moreover, the FCS laws would have degraded to it's basic form/function making most of the higher level FCS functions unavailable

[Cyrano]

Tejas has a quaduplex fbw fcs, perhaps one of the back up channels is always powered by an alternate (rechargeable) battery pack which assures min functionality in case of engine failure?

[chetak]

Tejas has a quaduplex fbw fcs, perhaps one of the back up channels is always powered by an alternate (rechargeable) battery pack which assures min functionality in case of engine failure?

Cyrano ji,

That is not how the quadruple fbw fcs is designed to work. In failure modes during flight, there will be redundancy but many a time, flight control laws may degrade in a controlled manner, depending on the specific nature of the failure(s) and in such a case, all available FBW channels will degrade identically

Additionally, hydraulic power may be required to operate certain flight control surfaces and in some cases, this may be fed by accumulators for a limited time but (single) engine out usually means that hydraulic power is mostly not available. That leaves mechanical back up to some control surfaces depending on the design criteria applied

A fully functional aircraft with FBW FCS will operate in normal law. But depending on the specific failure condition, there are four reconfiguration modes for the airbus fly-by-wire aircraft: alternate law 1, alternate law 2, direct law and mechanical law. Other aircraft like boeing will have some variation of these laws but not by much

May one suggest this link which may provide for a better understanding for the flight control laws. Most FBW FCSs will follow some variant or derivative of this black box methodology These are for commercial aircraft but the same principles will broadly apply pretty much across the board

https://en.wikipedia.org/wiki/Flight_control_modes

Once the coi is over and several weeks or even months have passed, some info is bound to trickle out

Best to wait and not speculate

[Manish_P]

Thank you, Chetak sir. I was under the impression (incorrect, as it now seems) that even in main power failure there would be some auxiliary system to provide power (for some time) to the critical components. Aim of discussion was to just get a better understanding and not idle (or malicious) speculation.

[chetak]

Thank you, Chetak sir. I was under the impression that even in main power failure there would be some auxiliary system to provide power (for some time) to the critical components. Aim of discussion was to just get a better understanding and not idle (or malicious) speculation.

Manish ji,

One is quite familiar with your posts, and their intent, content and also your commitment

banish the thought that anyone could mistake your posts

[Manish_P]

...
One is quite familiar with your posts, and their intent, content and also your commitment
...

Thanks for your consideration, Chetak ji and even more for your very educative guidance. Being a non-technical person it will take me quite some time to understand the details given at the link - let alone understanding the possible effects of departure from normal conditions.

As you rightly indicate, without further data forthcoming, the discussion will devolve into speculation. I think it's highly unlikely for the findings to be released to the public. So cease & desist from me.

[Rakesh]

https://x.com/ShivAroor/status/1768140865485365332?s=20 ---> Text from serving Tejas pilot after watching my show:

“Tejas flies like a dream. You can fight like a tiger and win. And both Tejas sqns have aircrew not only from MiG-21/27 fleets but also MiG-29, M2000 & Su-30 pilots. Unanimous!”

The show he watched:

[basant]

For the experts to examine and decipher, but this is what I gather about the backup power of Tejas that was probably utilized after possible engine power for its post-ejection flight. It's Emergency power Unit (EPU), not APU. See p. 13 for a schematic.

• ...
• 18. Engine Behaviour and Relight Considerations.
  Although the GE 404 engine is cleared surge free in its entire operating envelope, it is important to assess surge margins and identify a power setting to prevent surge at HAoA. The effects of over temping the engine and the effect of high rotational rates and corresponding gyroscopic moments on the engine need also to be studied before embarking on the campaign. Even if the engine does not flame out, the test director may have to decide between shutting down the engine to protect the engine or keep it on to protect the hydraulics. A clear criterion to help to decide this will have to be laid down. All planning for recovery from spin must assume that the engine will flame out. Thus height required for one failed relight plus a successful relight must be catered for. Lastly relight must be attempted after chute jettison only.
• 19.Requirements for Aircraft General Systems. All the ac systems will have to be checked for their capability to sustain high angular rates and n z up to +8g.
  (a) Hydraulic System. The hydraulic system is critical to recovery from spin as it powers the controls and ironically will be the first system that will be lost in case of engine flameout. The Emergency pump can supply flow for three min but not at the rate desired for full control activity. Thus it is necessary to provide a backup hydraulic power source, preferably for both main and emergency systems, of approx 60 lpm. The critical period for consideration whilst sizing the back up Emergency power Unit (EPU) pump will be from recovery to relight, when the chute would have been released and the ac flown in frozen gains until relight and recovery of on board hydraulics. While an APU could be used, it would probably not be able operate at the test altitudes. Currently the international standard is to use a hydrazine driven pump. However handling of this fluid has its own safety requirements and the EPU would have to be replenished at the taxy holding point prior to take off and a EPU contents indication should be available at telemetry. The triggering of this pump is also of importance as too early (switching it on before the test point) would deplete EPU fuel unnecessarily, and switching it on too late could lead to damage of the...
• ...

Source: Approach To High Angle of Attack Testing of Light Combat Aircraft (LCA) Tejas by Wg Cdr Vikram Singh, NTFC, ADA.

[Rakesh]

https://x.com/livefist/status/1775796482291220766 ---> BREAKING: IAF Apache damaged during precautionary landing in Ladakh.

IAF Statement:

[basant]

'Undulating terrain and high altitude'! Paraphrasing Himalayas.

[Manish_P]

There were recent reports of AH-64s issues in the US leading to grounding of the fleet (IIRC it was the national guard and not the regular frontline Army). It will be interesting to know if the issues are similar or of a different nature entirely.

Edit - read an article. The US ANG incidents seem to be attributed to low number of aerial hours leading to inexperienced flying resulting in the crashes...

[Rakesh]

https://x.com/livefist/status/1775796482291220766 ---> BREAKING: IAF Apache damaged during precautionary landing in Ladakh.

IAF explores options to retrieve copter from Ladakh
https://www.tribuneindia.com/news/india ... akh-608478
07 April 2024

https://x.com/ajaynewsman/status/1777164579262591363 ---> A Rs 650 crore Apache copter at 12,000 feet in the snow in Ladakh. How will the @IAF_MCC retrieve it? Try insitu repair, winch it up or disassemble it part by part?

[A Sharma]

Four Apache helicopters ‘down’ in 44 days; IAF’s is fifth

[konaseema]

I think IAF should refrain Apache's from High Altitude operations but use Rudra / LCH instead and restrict Apache's to plains and desert terrain.

[Rakesh]

https://x.com/EkNashwar/status/1777175491989962771 ---> Gold plated imports do not come with road side or should I say high altitude assistance.

[Prem Kumar]

So much for the hype the last few weeks about how Apaches will add teeth to the IAF to stare down China.......... if they can take off, that is

What a colossal waste of money for a few shiny toys!

None of the Import Bahadurs have uttered a pipsqueak about this. They were gratuitous with advice when a Dhruv crashed: Commission of Inquiry, grounding of fleet and what not

[Pratyush]

The silence of our import bahadurs is deafening.

I shudder to think of this was an LCH that had to make such a landing. We would not have heard the end of that.

[Manish_P]

I think IAF should refrain Apache's from High Altitude operations but use Rudra / LCH instead and restrict Apache's to plains and desert terrain.

The IAF is known to push the boundaries during peace time so that they bleed less during war time. They will be flogging the machines hard to know the limits.

A couple of years ago Brar_w had posted about the next generation of engines in development for the Apache. It promised around 20% more power IIRC. I think we will opt for the upgrade, should it get developed successfully.

https://www.defensenews.com/land/2022/0 ... army-says/

Having said that I do hope we order and field hundreds of Prachands - on both fronts