In the context of our Ground Based Air Defence Weapon Systems (GBADWS) it is quite fashionable to quote the high figures of percentage obsolescence (97 per cent or thereabout) and generally decry their very old vintage, thus coming to a quick conclusion that these are/will be incapable of countering the contemporary, as well as, the futuristic air threat.

Faced with the above common, the air defence warriors find themselves in an unenviable position. On one side, is indeed the reality of the years of vintage and obsolescence of their combat means, while on the other, is a grim realisation that any new induction must wait long years (7 to 10) before it actually gets operationalised. What does this demand? It demands that the existing (legacy) inventory has to be kept operationally relevant; come what may.

A Worldwide Phenomenon

Incidentally, the compulsion of sustaining vintage weapon inventory is not only typical of us (though our percentages of obsolescence are much higher), countries around the world have been carrying on with their vintage inventory. A snapshot:

• The Russian inventory of GBADWS still carries the weapons. ZSU-37, ZU-23-2, ZSU-57-2 besides others. Out of these, while ZSU-37, a 1943 vintage self-propelled (SP) gun got discontinued in 1962 upon the induction of Schilka weapon system, ZU-23, a 1960 vintage light gun is still in service, having seen widespread use in Libyan Civil War in 2011 and the current Syrian Civil War. Same is also true for ZSU 57-2 the SP anti-aircraft (AA) weapon of 1955 vintage.
• Chinese ZPU-1/2/4 2 AA Gun of 1949 vintage is still in service in China and in over 50 countries of the world having seen action from Korean War to the Syrian Civil War.
• The Pakistan Army Air Defence still operates the 1962 vintage Schilka Weapon System (ZSU23-4) and the 34-year-old Artemis Gun System of Greek origin.

Compulsions to sustenance of obsolete and vintage inventory is thus a worldwide phenomenon. In fact, no calibre, the world over, has ever been thrown away completely. Sweden, Italy and Singapore boast of their 40mm machines, Rheinmettal is up and about with its 35mm, Germany, Greece and Italy perfect their 30mms, the Russian block with Poland, Finland and Belgium are going strong with 23mm and the French, US, Israel and Korea with 20mm.

Challenges Galore

What challenges the legacy weapons throw up?

• The production lines of the main frame weapon get long closed down by the OEM; hence nothing fresh fetches up.
• Invariably, in yesteryears, the weapons which were bought as whole consignments, (generally on a government-togovernment agreement) hardly ever came with dedicated simulators. With decades of operations and training on war equipment itself, every single piece of old weapons goes far beyond its designed operational hours/service life.
• With the finite spares that come with the original consignment or the quantity that keeps coming till such time the production lines are alive can hardly suffice to keep the equipment going for decades of extended life. Effects:
• fter initial years of sufficiency, the paucity starts showing its ugly phase (around the mid-life overhaul) and keeps becoming worse year-on-year, not only diluting the quality of overhaul but also making difficult, the day-to-day sustenance.
• Since in yesteryears most legacy weapons came without the life-timebuy (LT B) of spares clause. These measures got applied as the situation becomes more critical and equipment sustenance started posing existentional threat.
• that too in a sporadic mode from the LT B route, fait accompli measures start to get applied. What are these?
• Cannibalisation from a part of inventory to keep alive the balance.
• Foregoing the overhaul option and only resorting to ‘optimisation,’ i.e minimum maintenance to keep the equipment from becoming EOA .
• The SAMs pose a totally different set of problems that is, of shelf-life. What to do when the OEM specified shelf-life expires. Obviously, shelf life extension. How many? One, two, three, after which the issue starts becoming critical, as the perishable parts simply start to age, the electronics components start loosing their reliability and not much can be said on the continued efficacy and lethality of the warhead lying in passive compact mode for nearly a few decades. Also, with legacy missiles, there are huge problems of reference standards that need to be applied after so many years of storage. Do the original tables apply? Are the tolerances and margins of the original to be kept unchanged or these be modified. If the latter, how much leeway exists, and more importantly, what is the logic? Not simple by any chance.

These are the type of challenges that stare the air defence warrior in the eye. Let us examine what can be done.

As regards the towed mainframe gun systems, very ‘enabling upgrades’ are possible. What do these promise?

• Removal the vintage target laying systems and replacing it with an electrooptical fire control system (E-OFCS). This amounts to a ‘complete revamp’ of the erstwhile mechanical sights for target laying with the following:
• A CCD Camera (normally with 16/18X, 1/4 CCD device, 1.6-230 FOV and focus range from1 to infinity).
• Thermal Camera (Typical 8-10mm band, 20-250 FOV, range in excess of 2 km, cooled).
• An eye-safe LRF (1-1.2mm band, FOV 2-2.5 MRAD, with ranges in the region of 18-20 km).
• A built-in fire control computing device that works out the gun laying data in bearing and elevation as the target is kept laid at the sight reticules.
• In order to increase the response of the gun to the fast manoeuvring air threat, the erstwhile mechanical or hydraulic drives of the gun are replaced with high response electric drives taking the gun movement response in bearing and elevation from 8-100 per second to 60-1,000 per second with acceleration in excess of 1,300 per second. This removes the erstwhile sluggishness and makes the gun sharply cut to the manoeuvring threat.
• An on board silent generator that powers the gun reducing dependence on bulky and noisy power supply source.
• Since the vintage ordnance cannot be retro-modified to receive the type of the cutting-edge ammunition of today, that has built in features of receiving roundto-round intelligence of instant muzzle velocity and resultant time-of-flight besides a palletised sub-munition filling with intelligent proximity-fusing for maximising the lethality and accuracy at the target end, optimisation of the existing ammunition is the way forward. In that, the conventional single charge pre-fragmented HE/HE-T and APC rounds are replaced with rounds carrying preformed fragmented cubes (PFFC) of tungsten material coupled with proximity fusing. Experience has it that PFFC firing is about 60-70 per cent more accurate that the erstwhile ammunition.
• Also, old vintage guns have limitations up to which, the rate of fire can be ramped up. With modification in the buffer design and reducing the length of moving part trail sequence, it has been possible to touch 300-330 RPM jacked from 240 RPM.

In self-propelled guns, in addition to all the above, the vintage analogue radars can be replaced by state-of-the-art digital phase array radars. These systems are not only more compact but also far more accurate in target tracking. Replacement of erstwhile fuel guzzlers gas turbine engines (GTEs) with fuel-efficient digital Power Packs is another smart measure that enhances the power and mobility of these old war horses.

Another challenge faced by legacy systems is night blindness. This void is slowly getting diluted as Thermal imager/FLIR / IIR base night sights are getting into place making legacy systems, night capable.

The near absence of spare supply of legacy equipment is a major issue. Since the LT B also results is a trickle supply, indigenisation of spares to the extent possible by any means including reverse engineering is the way to go. Such an effort is the hope of the users. The challenge is indeed colossal.

SAMs, beyond designated/extended shelf lives are a reality to be faced. This challenge can be addressed along several routes:

• Much shorter extensions (yearly) based on detailed intrusive test of lots with large sample sizes.
• Refurbishment of perished rubber parts where available.
• Re-ploughing spares by cannibalising some of the beyond-repair lots to keep live inventory sustained.
• Trying to develop reference standards through actual field tests of ‘as is’ lots. It is based on years of the above experience, that in RFP today where missiles are to be developed/procured along with the mainframe weapon, much smaller quantities are being initially asked for and balance, spread for a much longer period.

Some Takeaways

Finally a few experience points:

• Simulators along with the main equipment are a must. Operational hours will become more and more expensive as the years roll.
• LT B provision has to be a part of initial negotiations not a crises-afterthought. The desire to keep it out initially to keep costs low, ultimately results in paying many times over.
• Time frame for the OEM to keep spare lines open for an envisaged time schedule (plus stretch factor) must get mentioned/negotiated at the time of PNC/CNC. It is only at this time the OEM is ‘manageable’, not later.
• Indigenisation effort must start much earlier in the day if not ab-initio. Inventing the wheel when movement is required is not right.
• What where MToT is being negotiated:
• Like all ToTs, it is a mind game. It does not only happen on file but by total hand-holding till complete indigenisation is achieved (co-development/co-production/buy back are key words)
• The maintainer must be taken beyond BTP and BTS to the ‘know why’ in specific areas.
• The invariable tendency of the OEM to keep that last bit up the sleeve for a perpetual dependence has to be fought through.

Thus goes the dynamic of challenges as we endeavour to keep alive an old vintage and obsolete inventory besides living the promise of modernisation in the years to come.