A decade of investment in directed infrared countermeasures has inadvertently produced a cruel irony. It is now easier to protect helicopters from some of the world's most advanced smart weapons than from old-fashioned bullets and rocket-propelled grenades (RPGs).
The 6 August shooting down of a Boeing MH-47 Chinook that killed 30 Americans, eight Afghans and one military dog tragically underscored the dilemma. US officials have confirmed the helicopter was struck by an RPG, but they are continuing to investigate all of the circumstances of the subsequent crash.
It was the single most deadly attack on American forces in the nearly decade-long conflict, but it was no isolated example.
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© USAFA Chinook takes off with a Humvee sling-load, while helicopter reliability is crucial to survivability in Afghanistan |
Only 12 days earlier, another CH-47 was shot down by an RPG. That attack left two injured.
The previous most deadly attack in Afghanistan also involved a CH-47, which was shot down by an RPG-equipped insurgent in 2005.
The US Army does not publish details of helicopters lost in combat zones from hostile fire. but a 2010 public presentation by the US Department of Defense's Al Shaffer, principal deputy for defense research and engineering, claims hostile fire accounted for 36% of all helicopter losses in Operation Enduring Freedom at that time. This threat to helicopters has not gone unnoticed or unchallenged. There is virtually nothing a helicopter pilot can do to escape a well-aimed or lucky RPG shot. In many cases the pilot is not even aware of a small arms threat until it is too late.
MISSILE-THREATS
That lack of situational awareness is finally being addressed with a new wave of hostile fire indication (HFI) systems, now entering service.
Examples range from introducing the ground fire acquisition system for the Boeing AH-64 Apache attack helicopter fleet, to upgrading the AAR-47 missile warning system to detect plumes from RPG launchers, to the all-new joint allied threat awareness system (JATAS), which will scan for missile threats simultaneously with small arms. HFI technology is a first step but not the answer as systems can only alert the flight crew of gunfire or RPG launches after the fact - the shooter is allowed at least one free shot. If the HFI system is accurate enough, the pilot should be able to find the source of the attack and manoeuvre away or fight back. Defeating the incoming round remains a step too far for modern helicopters. While tanks and other ground vehicles are increasingly defended with active protection, the weight and complexity of such systems still rules them out for helicopters.
Developing a workable HFI system has been a goal for decades. In the late 1970s, UK-based MS Instruments developed an acoustic-based HFI sensor but it was limited to detection ranges of 20-30m. Due to the number of helicopters being shot down since 2003, the military has invested heavily in HFI technology.
COUNTERMEASURES
Some radical approaches, such as the BAE Systems E-scan radar, sponsored by the US Defense Advanced Research Projects Agency, seemed to have been abandoned. The new wave of HFI systems represent more realistic thinking. Modern systems appear to accept there is no adequate way to counter the first salvo of RPGs or bullets. The latest version of the AAR-47 will provide the pilot with the miss distance. As the AAR-47 is replaced by JATAS, the HFI systems will be upgraded to provided the angle and finally general location of the shooter. Meanwhile, companies competing for the US Army's common infrared countermeasures (CIRCM) programme have sensed an opportunity for possible future upgrades.
The CIRCM is designed to use a laser to jam incoming missile seekers, but a separate laser could also be added. This system would be used to "dazzle" the shooters after the HFI picks up an errant first shot. The dazzler is designed to make it uncomfortable for the shooter to maintain eye contact with the target.
Source: Flight International
