The United States has invested heavily to field the world's most capable tactical aircraft (TacAir) forces. Their state-of-the-art technologies deliver unequaled availability, reliability, and mission effectiveness. In addition to superb platform quality, they have superior aircrews and an unmatched supporting infrastructure. Although they are the world's most capable TacAir forces, limitations in guided-weapon targeting must be remedied if we are to achieve key goals outlined by Chief of Naval Operations Admiral Vern Clark in "Sea Power 21."
Targeting and weapon-delivery limitations gained much visibility in the 1990s. In Operation Desert Storm, Bosnia, and Kosovo, unacceptable percentages of airto-ground sorties were affected by weather. Weather and cloud cover often gave the enemy valuable sanctuaries and chances to regroup. In his after-action briefing, the commander of Operation Allied Force, Admiral James Ellis, highlighted these problems and warned of their potential effect in areas where weather conditions are less benign. (His comments were reminiscent of those of Air Force Chief of Staff General Merrill McPeak following Desert Storm eight years earlier.)
Operation Enduring Freedom in Afghanistan has benefited from weather conditions and relatively low-threat situations that offset the limitations. Precise targeting by ground troops has been a critical factor. Without it, aircrews either are unable to find targets or are forced to descend below prescribed operating altitudes, which exposes them to low-altitude fires. Precision weapons no longer are good enough by themselves—laser or electro-optically guided weapons cannot hit what pilots cannot see. The good news is that the latest lethal and affordable guided weapons can convert these shortfalls to transformational opportunities.
After Desert Storm, weapon developments were initiated to provide target standoff and high lethality in clear or adverse weather. It was hoped the new weapons might be affordable enough for routine use, thereby reducing dependence on less effective unguided weapons that were likely to create unacceptable collateral damage. The Joint Direct Attack Munition (JDAM) and the Joint Standoff Weapon (JSOW) were the first of the new guide-to-coordinate (GTC) weapons. Most of them use Global Positioning System (GPS) and inertial navigation system (INS) technologies to guide autonomously to coordinates stored in their guidance systems prior to launch. These GTC weapons are remarkably affordable; they can be released from long range and high altitude—and from above an overcast—without decreasing lethality.
Guide-to-coordinate weapons multiply TacAir combat effectiveness. Planners now think in terms of targets per sortie instead of sorties per target. But their need for precision target coordinates has had a dramatic effect on targeting and planning processes. The JDAM, for example, requires coordinates with about seven-meter circular error probable (CEP) accuracy. Better targeting translates directly to higher weapon accuracy and lethality. Unfortunately, the ability to generate GTC target coordinates has shortfalls in throughput and responsiveness. To achieve the revolutionary potential of GTC weapons in large-scale operations, the services must generate more precision-target coordinates faster.
Today, GTC weapons are targeted by time-consuming, centralized pre-mission imagery exploitation or by someone on the ground locating the target with a GPS device. Imagery exploitation proved its usefulness in Kosovo. This approach is most practical, however, against fixed or long-dwell targets that are unlikely to move during the considerable time lag between target imaging and attack. Aircrews do not sight targets when delivering GTC weapons; rather, the target is sighted when it is imaged. If a target moves after imaging, and GTC weapon targeting is not updated, the weapon will go to the designated coordinates, regardless of what is there at the moment. Although ground targeting may be crucial in close-air-support scenarios, it generally is less accurate and not always available. Tactical air power-projection operations cannot be dependent on ground forces.
Guide-to-coordinate weapon targeting used with TacAir is the most lethal and flexible choice. Many tactical aircraft carry GTC weapons, but none can self-target them against targets of opportunity. (The F-14 has a short-range, limited targeting capability.) Lack of GTC weapon self-targeting precludes the use of TacAir against mobile targets and denies it through-the-weather, near-precision effects. The self-targeting capability would enhance U.S. time-sensitive strike capabilities and mitigate the targeting gridlock that overwhelms key information nodes, such as the aircraft carrier intelligence center. At the same time, it would mitigate severe targeting deficiencies highlighted recently by various Navy agencies and study groups.
Ongoing interest in transformation and the great potential of GTC weapons would seem to ensure that aggressive action is taken to remedy TacAir targeting deficiencies. Disappointing results to date can be attributed to several factors. Perhaps foremost is the prevalent—albeit incorrect—perception that GTC weapons are useful only against fixed or long-dwell targets. Skepticism also may derive from the extraordinary difficulty operators have observed in establishing preplanned targeting capabilities. Finally, because the gap between current and needed self-targeting performance is vast, operators may be unaware that available technology can bridge it. Our challenge is to acknowledge that new targeting capabilities are essential if we are to overcome the debilitating effects of weather-induced operating conditions and centralized targeting. Until new targeting requirements are institutionalized, precious resources will continue to flow to incremental upgrades of current targeting technologies that are limited inherently.
Prosecution of fleeting targets by TacAir requires strong inter- and intraflight targeting that supports weapon capabilities and compliance with the prescribed tactics and rules of engagement (ROE). Although future unmanned air vehicles may perform targeting well, current models offer incomplete solutions. They can provide cueing and occasional targeting, but to cover the target set and compress sensor-to-shooter timelines, targeting must operate and survive where most targets are—in hostile airspace. Essential targeting requirements include a wide-ranging combination of capabilities. The following performance guidelines and rationale are intended to pave the way for more detailed analysis and discussion:
- Through-the-Weather/Clouds Capability. All-weather targeting would enable us to strike where and when we choose, but this capability exceeds today's technology—and budgets. Lack of through-the-weather capability is the root cause of historically high sortie loss rates. We need a commensurate ability to target day and night, in light to moderately adverse weather, through overcasts and smoke and haze.
- Precision Locating. With standard one-and two-thousand-pound weapons, a six-meter CEP ensures high single-weapon lethality against most targets. Analysis reveals one-thousand pounders are as effective as two-thousand pounders against most targets at this degree of accuracy. The TacAir targeting system should support self-targeted delivery of GTC weapons with a nominal six-meter CEP.
- Target Standoff Range. Targeting standoff performance must support weapon range capabilities and provide sanctuary from high-density threats. Tactical aircraft are unlikely to autonomously target limited inventory weapons such as the Standoff Land Attack Missile-Expanded Response, or to single-handedly engage strategic air defenses such as the SA-20 surface-to-air missile. Thus, these considerations should not drive targeting requirements. Targeting standoff range must support weapons such as JDAM and JSOW (and their derivatives) and provide sanctuary from tactical air defenses predicted for future battlefields. A 50-nautical-mile (nm) standoff capability meets these objectives.
- High-Resolution Imagery. High resolution enables operators to discriminate small targets, a primary objective of TacAir self-targeting. Sensor resolution is range dependent-another dependency that must be minimized. Required resolution is governed primarily by target dimensions and the target discrimination required by the ROE (such as "classify," "recognize," and "identify"). Target discrimination depends on the number of sensor resolution cells (pixels) that will fit on the target's critical dimension, phenomenology (radar or infrared [IRI/electro-optical [EO]), and complexity of the target scene. For equivalent discrimination, about twice as many radar pixels are required on a target as IR/EO pixels. Government target-set analysis reveals that 90% of mobile targets have a critical dimension of ten feet or more. Recognition with high confidence requires about 10 IR/EO pixels—or about 20 radar pixels—on the critical dimension. Combining these criteria, the targeting sensor must provide resolution between 6 inches (radar) and 12 inches (IR/EO). Discrimination is an inexact science. Sophisticated processing and automatic target-cueing algorithms can augment target discrimination, but experience shows that lower resolution sensors are unlikely to provide the quality of imagery that operators need. Complex target environments and stringent ROE may demand better resolution.
- Complete Targeting Performance. Targeting must provide all the foregoing performance attributes at ranges and altitudes that support optimal weapon employment; tradeoffs are unacceptable. One suitable benchmark for complete targeting is the ability to recognize with high probability a ten-foot critical dimension target in a moderately benign target scene at 20 nm, and to locate it accurately enough to deliver a JDAM through moderately adverse weather with an expected accuracy of six-meters CEP. Another would be to target a JSOW variant against a slightly larger mobile (or area) target from a range of 50 nm.
Although some may consider these targeting capability guidelines unachievable or unaffordable with current technology, available high-resolution synthetic aperture radar (HRSAR) modes have demonstrated they can meet them all. Off-the-shelf HRSARs can provide 4- to 6-inch resolution to ranges of more than 20 nm and 12-inch resolution at 50 nm. When integrated with embedded GPS and INS systems, or developmental onboard real-time imagery registration capabilities, they can meet the desired targeting performance guidelines. The Navy is preparing a flight demonstration of a high-resolution radar projected to meet or exceed these capabilities in its Shared Advanced Reconnaissance Pod product improvement program. This congressionally mandated demonstration is not programmed to lead to operational employment. Similar capabilities, however, could be packaged in a smaller pod compatible with most tactical aircraft and leveraged by joint forces using capabilities such as the Multifunctional Information Distribution System. Non-pod-equipped TacAir, surface combatants with emerging GTC weapons (for example, tactical Tomahawk), and new ground GTC weapons could be supported as well.
The HRSARs meet the suggested performance guidelines, but they do not meet all future needs. They cannot image or precision-target moving targets. In addition, they cannot penetrate foliage, are susceptible to jamming, and their imagery often is not as interpretable as IR/EO imagery. Recent technological progress suggests some important advancements are imminent: emerging 4-inch resolution radars will provide improved target discrimination; moving target imaging has been demonstrated; automatic target recognition is making significant progress; and there have been notable reductions in susceptibility to jamming. These advances would probably accelerate with increased service commitment to HRSAR targeting.
Support for increased investment in development does not constitute an either-or recommendation regarding other targeting technologies. Because single technology solutions are high-risk ventures, flexible multi-spectrum solutions should be pursued. At the same time, HRSARs appear to be uniquely capable of meeting many current critical targeting needs and offering the best path forward.
"Sea Power 21" highlights the need for better delivery-platform targeting. We should move forward now. High-resolution radars are planned for the Joint Strike Fighter and possibly the F/A-18E/F. But they are years away and the majority of our forces will not receive them. Further, current radars exceed the capabilities of the planned systems and may prove to be as affordable as current IR/EO pods.
Persistent and sustained precision fires are critical to future operational concepts and cannot be contingent on fair weather and centralized targeting. Until targeting deficiencies are remedied, our tactical aircraft will lack the responsiveness necessary for modern warfare.
Arch Turner, a retired naval aviator, is a consultant for Booz Allen Hamilton. He works at the Office of Naval Research.