by Michael Puttré and Michal Fiszer
Feb. 1, 2002

 

 

Close air support has to be the most dangerous mission in fixed-wing combat aviation. Even in peacetime, the large number of tasks that must concern the typically lone pilot conspire with the proximity to the ground to put him on a very fine curve with little margin for error. Add the necessity in wartime of dealing with ground-to-air and possibly even air-to-air threats, and it is difficult to imagine a more hazardous assignment.

Aircraft specializing the close-support mission by and large have single place cockpits, as exemplified by the US A-10, Russian Su-25 (Frogfoot), UK/US Harrier, and UK/French Jaguar. Of course, close air support as a mission can be and often is flown by a number of platforms, including fighter, strike fighter, and bomber aircraft. Furthermore, gunship aircraft, such as the US AC-130, are designed to deliver staggering firepower in support of troops on the ground. Nevertheless, close air support classically involves a fast mover that can get into and out of a mission at the very tip of the spear, delivering ordnance precisely as directed by forward air controllers (or simply a soldier with a radio). Such combinations can turn the tide of a pitched battle.

Yet close-support aircraft are often not as highly regarded as their fighter-, strike-, and bomber-pilot brethren. One retired US Air Force pilot who had flown both the A-10 and the F-16 fighter said that flying the A-10 was more challenging - and entertaining - than the F-16, but for career purposes he had switched to the Fighting Falcon when the opportunity arose. More expensive, high-performance tactical aircraft carry the prestige and are often first in line to receive the latest EW systems and enhancements as they become available. Funding for protecting close-support aircraft often takes a back seat to programs for protecting higher-profile aircraft. Such was the case when the AV-8B Harrier close-support aircraft of the US Marine Corps were dropped from the list to receive the AN/ALR-67(V)3 radar warning receiver that is intended to supercede the AN/ALR-67(V)2, while F/A-18C/D Hornets F/A-18E/F Super Hornets will get theirs.

The tried-and-true combination of radar warning receiver, countermeasures dispenser, and radio-frequency (RF) jammer for protecting tactical aircraft are commonly deployed on close- support aircraft as well. However, the particulars of the close-support mission have had an impact on how these systems are used and what threats they are designed to counter. Furthermore, the evolving battlefield is offering new short-range air-defense threats, such as missiles and guns with advanced infrared (IR), laser-ranging, and electro-optical fire control that existing electronic countermeasures (ECM) fits are not designed to handle.

The challenge for developers of ECM systems for close-support aircraft will be to adapt existing systems to these threats, improve the level of automation to reduce pilot stress, and develop new systems that are effective and economical enough to actually be acquired. On the flip side, air forces will have to agree that close-support platforms and aircrews are not second-string units on the roster but are deserving of self-protection systems in keeping with the danger of their mission.

Even Warthogs Need Protection

The Lockheed Martin A-10 carries an obsolescent self-protection suite that includes the Northrop Grumman ALR-69 radar-warning receiver, BAE Systems AN/ALR-40 countermeasures dispenser, and the BAE Systems AN/ALQ-131 ECM jammer pod. All of these are widely deployed, "mature" systems. The ALR-69 is not able to process airborne and pulse-Doppler threat radars. The ALQ-131 jammer pod is subject to periodic upgrade, and has a niche in the F-16 market, although the A-10 is not a typical beneficiary of this.

Nevertheless, if the A-10 crews are required to make do with second-string self-protection systems, they have received welcome assistance in the form of the AN/ALQ-213(V) EW management system from Terma (Lystrup, Denmark). According to research performed by the US Air Force, close-support-aircrew workload is seriously increased by the necessity of interpreting and controlling EW systems. The ALQ-213 provides a single cockpit interface to integrate the installed self-protection suite on the aircraft, reducing pilot workload. The ALQ-213 is currently employed in various threat situations, ranging from early- warning radars to site air defenses that use RF and IR guidance and cueing systems. The aircrews benefit from a HOTAS [Hands on Throttle and Switch] control mode and integrated display of the radar warning receiver, radar jamming, and countermeasures-dispenser status. They can also monitor the missile warning systems while wearing full night vision goggles, which is of particular importance on today's battlefield.

"Until the implementation of the ALQ-213, electronic-combat cockpit- control units limited the pilot's EW responses," said Connie Peek, ALQ-213 program manager in the Pods and Special Operations Division, Electronic Warfare Management Directorate, Warner Robins Air Logistics Center, (Robins AFB, GA). "Mission complexity is increased with the use of night-vision goggles and the need for compatible cockpit lighting. Improvements to the pilot vehicle interface provide control of all EW systems while reducing pilot workload and permitting rapid selection of optimized threat responses."

The ALQ-213 is loaded with mission data derived from tactics- development testing and is continually updated through the EW database maintained by the USAF Air Warfare Center (Eglin AFB, FL). The correlation of the self-protection sensors and countermeasures provides a synchronized response to the threat, applying the most timely and most effective response. "Semi-automatic modes of operation accumulate sensor data to ascertain the best response, set-up the EW systems for that response, and wait for aircrew or platform cue to execute," Peek said.

The system is regarded as an acquisition-reform success story, and a particular feather in the cap of the Foreign Comparative Test (FCT) program. The ALQ-213 was originally developed by Terma for the Royal Danish Air Force to achieve an integrated EW capability for its F-16 aircraft. It was also selected by Lockheed Martin for the USAF/European Air Forces F-16 Mid-Life Upgrade. The German Air Force has also procured this system for C-160 transports. Terma received an award from the Office of the Secretary of Defense in 1996 for what has become the most successful FCT acquisition in the history of the program. The ALQ-213 is in continuing production with more than 900 systems contracted for delivery to the USAF. The system is installed in older Air Force Reserve A-10s and F-16s. Denmark, Norway, the Netherlands, and Portugal will also employ the ALQ-213 on their F-16s.

According to Peek, A-10s and F-16s equipped with ALQ-213s successfully support Southern and Northern Watch missions over Iraq. Several proposed upgrade programs are in the works to expand the integration and further reduce aircrew EW workload. "Through the use of digital processing and reprogrammable software, the ALQ-213 is generally able to accommodate training and tactics changes without changes to hardware," Peek said. "This will ensure that the ALQ-213 will remain an effective self-protection solution for aircraft crews that may not include trained EW officers."

Best Frogfoot Forward

The Soviet Air Force started defining the close-support role for the Air Force in 1973, after analyzing experiences from the Yom Kippur War. It was also born of the new, more "non-nuclear" view of the future battlefield in the '70s. However, the Soviets wanted a supersonic aircraft for close support, based on the Anglo-French Jaguar concept. Thus, they ordered next version of Su-17 (Fitter) to be able to fulfill the close-support role. The Su-17M3 (Su-22M3 export version) appeared in the mid '70s, along with the MiG-27 (Flogger H). These aircraft had the more precise KN-23 fire-control system and also a basic tactical ECM fit. The latter included the SPO-15 Sirena 10 radar warning receiver and eight ASO-2V chaff/flare dispensers. These aircraft could also carry the SPS-141MVG Gvozdika jamming pod, optimized against the Nike Hercules and Hawk SAMs, as well as airborne fire-control systems.

At the same time, the Su-25 (Frogfoot) program proceeded as a rare private venture of the the Sukhoi Design Bureau. This aircraft more closely mirrored the thinking behind the US A-10: that a subsonic, highly maneuverable aircraft with good armor and excellent loiter time over the target would be more valuable than a supersonic strike platform on close-support missions. When Soviet authorities came around to accepting the idea of the Su-25 subsonic close-support aircraft in the late 1970s and early '80s, they ordered it to use the same fire-control system as used on the both the Su-17M3 and MiG-27 aircraft. Thus, the basic Su-25 also had the SPO-15 Sirena 10 radar warning receiver, four ASO-2V chaff/flare dispensers, and provision for the SPS-141.

Over time, the Su-25's ECM fit was deemed unsuitable for the close-support role, mainly because of developments in Western short-range air defenses. The latest version of the Su-25, called Su-25TM by the Russian Air Force and Su-39 by Sukhoi Design Bureau, was equipped with the more capable Pastel radar warning receiver, a pair of BVP-50-30 chaff/flare dispensers, and provision for the more modern Omul double-pod jamming system that is optimized for Rolland, Rapier, and Hawk. Omul is a pod version of the Gardenia jammer used on the MiG-29 (Fulcrum C). The Su-25TM never reached operational units; however, numerous prototypes were constructed. Only the basic version of the Su-25 is still used by Russia, Ukraine, and Belarus. It is likely that some of the aircraft have had the ASO-2V replaced by two BVP-50-30 chaff/flare dispensers (for a total of 60 rounds apiece). The rest of the ECM remains the same.

It is instructive to track the changes in the Su-25's ECM fit - even in theory - because they reflect how the close-support concept evolved along with Western air defenses and the Soviet experience in Afghanistan. In particular, early Soviet decisions to make use of existing ECM systems for tactical aircraft were to prove a mistake, largely due to the increased exposure of close-support aircraft to air defenses. Short-range air defenses -- such as Rapier, Rolland, and Stinger -- were to prove especially problematic.

The SPO-15 Sirena radar warning receiver 10 is the more capable version of the SPO-10 Sirena 3 used on the MiG-21R (reconnaissance version). It can detect and track threats working in the 2-15 GHz range. It is based on a wideband receiver and does not determine the threat frequency but classifies the enemy systems based on other inputs, such as pulse width and pulse-repetition frequency, time between pulses, etc., and it recognizes continuous-wave radars (such as the signal of the Hawk illumination radar). It shows the direction towards the enemy radar with an accuracy of 15 degrees in the front hemisphere, 45 degrees in the rear hemisphere, and 30 degrees on both sides. The Sirena 10 also shows whether the threat is above, below, or at the same level as the aircraft. Pilots that have used the system report that it is not user friendly. It has a fixed threat library that is preset at the factory and cannot be changed at the unit level. The Pastel radar warning receiver is an improved version of SPO-15, with the capability to designate targets for anti-radiation missiles (in the Soviet/Russian system, all tactical strike aircraft are required to be capable of anti-radar missions; see "Crimson SEAD"). It works between 2-18 GHz and has a more extensive threat library, although this is probably also fixed at the factory and cannot be reprogrammed in the field.

The ASO-2V chaff/flare dispenser has 32 tubes for 26mm rounds that can be launched in a number of preset sequences. Reportedly, the rounds are not very effective -- especially the flares, which were too small. The effective radar cross- section of a single round of chaff is about 5 square meters. The BVP-50-30 is a 30 tube, 50mm chaff/flare dispenser that is much more effective than the ASO-2V. The 50mm flares are much larger, with a burn time of eight seconds, and can jam the Stinger, which the 26mm flare rounds couldn't do. The effective radar cross section of a 50mm chaff round is 15-20 square meters.

The SPS-141 jamming pod provides deception jamming, affecting the range and azimuth display of the threat radar. It can also "break" the radar track. It works in four modes: individual protection, two-aircraft protection (both aircraft having the SPS-141, cooperating with each other in jamming the enemy radar), "Doppler noise" mode, and low-level mode, where the equipment uses the terrain-bounce effect in jamming. Omul works in very much the same ways and is optimized against a wider range of threats: Hawk, Roland, Rapier, and Patriot (although it is difficult to assess how effective it is against the last system).

An interesting footnote to the Su-25 story is the upgraded Su-25K Scorpion, developed by Tbilisi Aerospace Manufacturing (TAM) (Tbilisi, Republic of Georgia) and Elbit Systems (Haifa, Israel). The Scorpion has a new advanced navigation and avionics system capable of integration with both NATO and Eastern European weapons and pods. It has a new glass cockpit with two multicolor LCD displays and a head-up display (HUD), a Multi Modular Role Computer and two 1553 MUX bus interfaces, and a digital moving map. The base self-protection suite is that of the improved Su-25TM, although Elbit said that any customer-defined self-protection suite could be accommodated.

Asking For It

According to Nick Walster, manager of business development for fixed-wing aircraft EW at BAE Systems Avionics (Stanmore, Middlesex, UK), the customer gets the sort of EW systems for his close-support aircraft that he asks for (and pays for). BAE Systems makes integrated EW suites for a number of aircraft that perform close air support, including the Harrier, Hawk, and Tornado. In each case, the suite is fully automatic. Kits are also capable of being reprogrammed in theater with updated threat libraries so expected RF threats can be detected and countered. "The UK philosophy is to provide automatic response for EW and countermeasures, without a man in the loop," he said. "This is an operational issue, not a technical one."

While technology might not be a limiting factor for the standard fit of radar warning receiver, countermeasures dispenser, and RF jammer, it is something of a problem when it comes to countering IR threats. Close-support aircraft universally carry flares for IR defense, but none carry any missile-approach-warning systems for optically cued threats. This is because ultraviolet (UV) missile warners have performance issues, and IR missile warners are prone to false-alarm problems. This is troubling because of the danger posed by IR-guided missiles: reportedly four US Marine Corps AV-8B Harriers were lost to Iraqi shoulder-fired missiles during the Gulf War in 1991.

Dov Granot, business development manager for the Elisra Group (Bene Beraq, Israel), said excellent threat-warning systems are of paramount importance for close-support aircraft - even more so than for aircraft that operate at high altitude. While missile-warning systems are available that use both UV and IR technology to improve performance and reduce false alarms, such systems do not come cheap. In the realm of countermeasures, modern radar-guided threats have improved capabilities against jamming, reducing the effectiveness of ECM systems with pedigrees dating from the 1970s. In response, jamming systems must be able to attack precise points instead of using barrage- and noise-jamming techniques. These are also expensive. "Basically, it is a budget issue," Granot said.

Even so, Granot agrees that national priorities are at the heart of how air forces equip their close-support aircraft. "Israel's philosophy is that an aircraft needs to be able to protect itself from start to finish, from take-off through landing," he said. "The US has specialized EW aircraft that cover an area - a zone defense - that take some of the burden off the strike aircraft in terms of self-protection."

Whatever the philosophy, it is harsh reality that the threat environment is evolving all the time. The danger posed by advanced AAA systems, always a serious threat, is increasing as they are equipped with high-frequency radar, day/night sights, and laser rangefinders that reduce or even eliminate the need for air-search radar. The improved ZSU-23-4 "Shilka" self-propelled guns employ such systems. Short-range air-defense missiles that use laser beamriding guidance, such as the Thales Starstreak, are being deployed that cannot be detected by radar warning receivers and that are immune to chaff and flare. Such developments might argue for the inclusion of advanced laser-warning receivers on close- support aircraft, such as those carried on some combat helicopters, although there are no announced plans to do so.

One possible result of the increasingly hostile threat environment could be the eventual elimination of the close- air-support mission. In the US, the A-10 is being designated OA-10 in recognition of its growing importance as a forward-air-control platform. Increasingly, the role of tank buster is being taken up by the F-16 in the Air Force and F/A-18 in the Navy and Marines. New- generation precision weapons with GPS- guidance systems that can be programmed in flight mean that ground- support missions can be flown at near stand-off ranges, so long as everybody is working from the same map.

They say if you can't stand the heat, stay out of the kitchen. Perhaps close-support aircraft will be doing just that. 

 

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