breaking the kill chain

Last Updated: Mon Jan 27 11:18:09 UTC 2014

Breaking the Kill ChainAir Power Australia - Australia's Independent Defence Think Tank

Air Power Australia NOTAM 27th January, 2009

WgCdr Chris Mills, RAAF (Retd)

Contacts: Peter Goon Carlo KoppMob: 0419-806-476 Mob: 0437-478-224

Su-35 demonstrator #709 displays a mix of R-27 Alamo and R-77 Adder BVR missiles (KnAAPO).

Air combat relies almost completely on the effectiveness of missiles. Yet for a missile to down an aircraft theremust be an unbroken kill-chain of events terminating in the explosion of a warhead in close proximity to a vitalpart of the target aircraft.

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Some people believe that missiles have near perfect chance of killing a target. While modern missiles aretechnological marvels of modern warfare, they have faults and weaknesses, not the least being critical phases ofthe kill-chain.

The mathematics is quite simple. Sort the kill-chain into a sequence of events, starting with the missile on itslaunch rail and ending with its warhead exploding. Assign a Likelihood of failure at each step. Then take theprevious link in the kill-chains Hit Probability, subtract the Likelihood of Failure from one, and multiply.

This analysis is perhaps best illustrated by the potentially lethal game of Russian Roulette where one round isloaded into a six-shot revolver, the cylinder is spun to stop at a random chamber, the muzzle is placed againstthe forehead and the trigger pulled. The following is the players chance of survival after a series of plays:

Russian RoulettePlayer is Alive At the Start 1Chance of a Misfire 0.05Likelihood of a Firing 0.95Chance of Surviving Infinite Plays 0.05

Play Chance of Selecting a Round Chance of Not Selecting ARoundCumulative Chance of

Surviving

1 0.17 0.83 88%2 0.17 0.83 73%3 0.17 0.83 61%4 0.17 0.83 51%5 0.17 0.83 42%6 0.17 0.83 35%7 0.17 0.83 29%8 0.17 0.83 24%9 0.17 0.83 20%10 0.17 0.83 17%11 0.17 0.83 14%12 0.17 0.83 12%

Reference:http://library.wolfram.com/infocenter/MathSource/5710/

What is may seem to be intuitively obvious to some a player will be certain to die after 6 turns of RussianRoulette - is actually untrue. Even after twelve plays where each chamber has a chance of being selected twice,and taking into account a 5% unreliability of the weapon, the player still has a 12% chance of surviving.


Developmental AIM-120A round destroys a QF-102 drone (U.S. Air Force photo)

Air Combat Kill Chains

Modern air combat is a high-tech, high-competency, deadly business. Each side tries to maximise theperformance, reliability and survivability of each step in its kill-chain, while maximising their own ability to disruptone or more steps in the enemys kill-chain. These actions take place simultaneously, at high speed and attimes under high stress, so it is often a case of the survival of the fastest and the fittest

Breaking a Beyond-Visual-Range Kill Chain

The following describes a typical kill-chain, and how an enemy might seek to disrupt it. After reading the steps inthe chain, assign representative values to the Kill-Chain Analyst model at the end of the NOTAM to make anoverall assessment of the reliability of a BVR missile.

Active Missile Confirmed on Launch Rail. The pre-flight check shows an active missile on the launch rail. Oris it? Has an inert round been loaded by mistake, or has the round sabotaged on the way to the flight-line?


Search and Track Radar Jammed. Electronic Counter Measures (ECM) are designed to prevent theenemys radar finding, locking and tracking an aircraft. Modern air-intercept radars are jam resistant but notjam-proof.

Launch or Missile Failure. Missiles are often carried for several sorties before being fired or returned to amaintenance depot for test and refurbishment. Air combat places a high stress on missiles, especially in harshclimates. As an example, in Vietnam the Pk (kill probability) of the AIM-7E was less than 10%, with low reliabilitybeing one of the largest sources of poor performance.

Guidance Uplink Jammed. Jamming the missile guidance uplink is not considered very effective, as suchlinks are directional and the missile antenna is usually pointed away from the target. In future warfare whereaircraft are spread out and Network Enhancements are in place, it may be possible to a buddy looking acrossa launch to disrupt the missile guidance by jamming it with AESA radar or a high-power microwave device.

Seeker Head Jammed or Diverted. This way of disrupting a kill-chain has a higher chance of success, as themissiles radar small radar seeker requires high sensitivity to produce acceptable autonomous operationalranges. Digital Radio Frequency Memory jammers record and replay the missiles emission but in a waydesigned to deceive the missile into computing a false location of its target. Flankers often carry the KNIRTIL005-S Sorbtsya wingtip jammer pods. In more advanced jammers, this configuration is capable of generatingcross-eye jamming which introduces an angular error into the missile seeker.

Chaff or Decoys Seduce Seeker. Generally, chaff is considered ineffective against modern missiles, is theinternal signal Doppler processing discriminates chaff returns once they stop moving. What if the chaff moves atabout the same rate as the aircraft? Forward firing, slow burn rockets or perhaps a modified round fired fromthe targets gun (e.g. the GSH-310 30 mm,) could draw a missile away.

Seeker Chooses Towed Decoy. Towed decoys work. If they did not, why fit them to vulnerable aircraft likethe F/A-18E/F Super Hornet? Flankers may use a KEDR towed decoy. Used in conjunction with a MissileApproach Warning System (MAWS) the pilot can present the towed decoys to the missile before it reaches theaircraft e.g. about 140 degrees off the nose. With DRFM replays of the missile seeker head emitted pulses,decoys can be very effective at making the missile track away from the aircraft, disrupting the kill-chain.

Aircraft Out-Manoeuvres Missile. Why fit a MAWS to a fighter aircraft? Is it to give the pilot a chance tomutter a quick prayer or curse before dying, or to provide a chance to duck the incoming missile? The physicsare that G-Forces in a tracking turn of a given radius are a square of the speed. A typical engagement has thefighter doing Mach 0.9 and the Missile is arriving at Mach 3.6 - four times as fast as the fighter. If the fighter cangenerate a 5 G turn, the missile must track at 16 times the G to follow the aircraft, an 80 G turn. BVR missilesgenerally max-out at about 40G, so depending on the aspect, cannot track, so fly past the aircraft and miss.

Fuse or Warhead Failure. Even at the end of a long kill-chain, the warhead must fuze and explode closeenough its target to kill or inflict serious damage. Here is another opportunity for failure or hostile jamming.

Su-35 demonstrator displaying the R-172/AAM-L, the R-27ET1 Alamo and the R-77 Adder at MAKS 2007(KnAAPO).

BEYOND VISUAL RANGE RADAR MISSILE


Link # DescriptionLikelihood of

Failure Hit Probability

1 Active Missile Confirmed on Launch Rail 0.001 0.9992 Search and Track Radar Jammed 0.050 0.9493 Launch or Missile Failure 0.050 0.9024 Guidance Link Jammed 0.030 0.8755 Seeker Head Jammed or Diverted 0.300 0.6126 Chaff or Decoys Seduce the Seeker 0.050 0.5827 Seeker Chooses Towed Decoy 0.500 0.2918 Aircraft Out-Manoeuvres Missile 0.400 0.1749 Fuse or Warhead Failure 0.020 0.171

PROBABILITY OF A BVR MISSILE KILL: 17.1%So, putting all the steps together in the Kill-Chain Analyst model, and providing reasonable estimates for thelikelihood of disrupting each step in a modern engagement, this is the result less than a 20% kill probability, orput another way, four out of five missiles fired will miss.

Is this a reasonable result?

Analyses done elsewhere have shown that the history of the AIM-120 in BVR engagements has been 6 kills from13 shots, a kill probability of 46%. However, the targets were straight and level, un-alerted aircraft, not fittedwith electronic counter measures. One was a helicopter. So, for modern warfare when the enemy is networkenabled, fully cognisant of the tactical situation, and takes every opportunity to break the kill-chain, a sub-20% killprobability for BVR missiles is likely to be the new reality.

The latest generation of Western WVR missiles employ Focal Plane Array seekers with target recognitioncapability and high resistance to infrared countermeasures. Depicted imagery from the seeker of a RaytheonAIM-9X missile, which uses an Indium Antimonide bandgap detector array. Russian industry is working onsuch an FPA seeker, what is unclear is whether it will employ bandgap detector or superior two colour QWIPtechnology. When it enters production it is likely to become a block upgrade and new production item for BVRmissiles such as the R-27ET and R-77T.

Breaking a Within-Visual-Range Kill Chain

In recent times, some people have had such (over)confidence in their BVR weapons, they have not paid muchattention to within-visual-range contests. The exception is those unfortunate to be trapped in Low Density / High


Demand craft that dont have the ability to escape from a fighter transports, tankers and airborne earlywarning aircraft or other Intelligence Surveillance Reconnaissance aircraft. Some of these make a half-heartedattempt at self-defence by fitting flares and chaff dispensers, and Directed Infra-Red Counter Measures(DIRCM) systems.

As with the WVR case, read the steps in the chain, assign representative values to the Kill-Chain Analyst modelat the end of the NOTAM to make an overall assessment of the reliability of a WVR missile.

Active Missile Confirmed on Launch Rail. As before, is this a real round or a dud?

Launch or Missile Failure. Failures are possible as with BVR missiles, but WVR missiles tend to bedesigned for higher G loadings and have fewer parts to fail, so expect the launch reliability to be higher.

Directional Infrared Countermeasures Effective. DIRCM is rarely fitted to fighters, so if none is present, theeffectiveness is set to zero.

Seeker Head Jammed or Diverted. Older Infra-Red missiles like the early Sidewinders used a simpletracking device that could be diverted by a frequency-modulated signal the head would slew away and breaktrack. No such luck with modern, imaging seekers, where internal digital signal processing detects anddisregards such measures.

Flares or Decoys Seduce Seeker. Generally, simple flares are considered ineffective against modernmissiles. What of the future? Moving flares and decoys might have a chance, except an imaging seeker headwill be looking for a large object, and will reject point sources. Two colour seekers will look at the blackbodycharacteristics of the infrared targets and since flares are hotter than tailpipes, reject them.

Seeker Chooses Towed Decoy. While there have been plans to include infra-red emitters in a towed decoy,this play could be defeated by an imaging seeker.

Aircraft Out-Manoeuvres Missile. Dogfight WVR missiles have been designed to fly close, high-G knifefights. They have turning capabilities of about 80G and have attack profiles that reduce closing speeds makingit possible to track a high-G target. Generally, it will be rare for a fighter to duck an incoming WVR missile.

Fuse or Warhead Failure. Reliability is still an issue, but the smaller size of the WVR missile also means thewarhead is smaller. Large aircraft like the Flankers have armour-like structures around the engines, which arewidely spaced, so a hit might damage, but fail to kill this type of aircraft.

WITHIN VISUAL RANGE INFRA-RED MISSILELink # Description Likelihood ofFailure Hit Probability

1 Active Missile Confirmed on Launch Rail 0.001 0.9992 Launch or Missile Failure 0.030 0.9693 Directional Infrared Countermeasures Effective 0.000 0.9694 Flare or Decoys Seduce the Seeker 0.050 0.9215 Seeker Chooses Towed Decoy 0.000 0.9216 Aircraft Out-Manoeuvres Missile 0.100 0.8297 Fuse or Warhead Failure 0.100 0.746

PROBABILITY OF A WVR MISSILE KILL: 74.6%This is a result that looks a lot more like the Manufacturers brochure and promises. Apart from the reduction ofkill probability arising from the size of the warhead, the WVR kill-chain has fewer links and less areas ofvulnerability to attack, so a WVR missile launched within its engagement envelope may well kill at this rate.

This result matches the record of AIM-9L firings in the Falklands conflict where 26 missiles were fired for 19 kills a Pk of 73%.

Those LD/HD aircraft that fit a DIRCM effective about 50% of the time will still have to endure a kill-probability ofabout 40% per missile. And if the missiles miss, there are still guns to shred large, slow and soft aluminiumstructures.


Su-30MK launching an R-77 (KnAAPO)

The Bottom Line

Most fighter pilots rightfully fear a merge followed by a knife fight where WVR missiles are loose. Thesemissiles may be unable to discriminate between friend and foe, and like a rabid dog, will attack the nearesttarget they find. Mutually Assured Destruction (MAD) is possible, as the engagement ranges of WVR missilesare often about the same, so each side might fire a missile and down the opposition.

An inconvenient though inevitable and accurate assessment of this analysis would be that as BVR missiles losekill probability because of disruption of the kill chain, merges and WVR engagements are more likely, with higherlosses all-round.

If future air combat, those with the most BVR rounds, the ability to egress a fight before a merge, and flyingtough, multi-engine aircraft that can take a WVR missile hit and still get home, will be the winners.

Excel Spreadsheet for Modelling Pk [Click here ...]

Related ReadingThe Russian Philosophy of Beyond Visual Range Air Combat [Click for more ...]

F/A-18E/F Super Hornet vs. Sukhoi Flanker Analysis [Click for more ...]

Sukhoi Flanker Analysis [Click for more ...]

F-22A Raptor Analysis [Click for more ...]

Joint Strike Fighter Analysis [Click for more ...]

Air Power Australia Website - http://www.ausairpower.net/Air Power Australia Research and Analysis - http://www.ausairpower.net/research.html


Artwork, graphic design, layout and text 2004 - 2014 Carlo Kopp; Text 2004 - 2014 Peter Goon; All rights reserved. Recommendedbrowsers. Contact webmaster. Site navigation hints. Current hot topics.

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