A sad reality of military air operations is that sometimes things go wrong. Whether through hostile fire or other causes, military missions occasionally shift under the urgent mandates of combat search and rescue (CSAR).

One of the most critical aspects of CSAR operations is the ability of downed survivors to quickly and reliably convey their situations and location data to rescue elements.� 

In many instances, those capabilities are provided through the AN/PRC-112 series of CSAR radios. In additions to voice communications capabilities, early models of the 112 (A/C models) allowed rescue aircraft to "ping" the downed pilots' radio and determine the pilots' position through the quick return burst with Distance Measuring Equipment (DME) technology. In a perfect world, the bursts were brief enough to preclude the ability of hostile forces to home in on the signal. But the world isn't always perfect, so in the mid-1990s, General Dynamics Decision Systems (then Motorola) introduced improvements to the 112 (B/B1/G models) that the company calls the "Hook2".

The latest Hook2 models add the capability for CSAR assets to obtain the survivor's Global Positioning System (GPS) location while also allowing for two-way encrypted text messaging.

"So now, not only do you â??ping' the survivor - or the survivor can originate a burst of information - but you now can get their position. You can exchange messages to and from the survivor," explained Chris Brady, director of Assured Communications Systems at GDDS.

While downed aircrew communicate through their 28 ounce, 7.69 inch by 3 inch by 1.5 inch PRC-112, rescue craft receive and respond to survivors through small Quickdraw and Quickdraw2 interrogators that plug into the UHF radio in multiple airframes - both manned and unmanned.

Reflecting on the significance of the latest models compared with earlier versions of the system, Brady said, "Hook2 brings a rescue within what we call â??the golden hour.' Statistically it has been proven that if you're going to get captured it's going to happen within that first hour. So that first hour becomes a race against time. The traditional methodology of determining where the person is, plotting a rescue back at headquarters, and then organizing a mission can take several hours. With our system you have instantaneous awareness throughout the theater and in those forward deployed units to go ahead and execute the rescue literally within minutes."

These new abilities, combined with recent operational experiences, are helping to expand utilization of the Hook radios throughout the U.S. military. Clear evidence of this expansion can be found in the recent company announcement of three recent U.S. Air Force orders.

Somewhat surprisingly, the new PRC-112-series orders are taking place against a backdrop that features simultaneous joint service development of the CSAR Combat Survivor Evader and Locator (CSEL) Survivor Radio System. Composed of three segments - over-the-horizon, ground, and (AN/PRQ-7) user - program descriptions credit CSEL with providing "the survivor/evader in the field (typically downed aircrew) with: precision GPS-based geoposition and navigation data, two-way over-the-horizon (OTH) secure data communications to Joint Search and Rescue Centers (JSRCs), OTH beacon operation, Line-of-Sight (LOS) voice communication, sweep tone and swept tone beacon capabilities."

While CSEL continues, the most recent Hook2 order covers 744 new production AN/PRC-112G radios for the U.S. Air Force Air Combat Command and comes on the heels of two earlier orders to upgrade to nearly 1,500 earlier-model AN/PRC-112 radios, adding GPS location capability and encrypted two-way messaging, features that are inherent in the new production AN/PRC-112G radios.

Taken together, the three recent contracts will bring the total number of fielded Hook2 radios to more than 11,000. The radios are currently used by all U.S. armed services, U.S. Special Operations Command, the United Kingdom, Australia, New Zealand, Germany, Spain, Sweden and Portugal.

"We can't go into who else is showing interest but suffice it to say that there are probably on the order of a dozen other countries showing interest," Brady said.

Although many operational specifics from Operation Iraqi Freedom have not been formally released, an idea of the U.S. and coalition combat experiences with the Hook2 can be found in one CENTAF study focused on a numerical analysis of a 720 hour operational period from March 19 to April 18, 2003.

That one-month period saw seven manned coalition aircraft (four AH-64D, two AH-1W, and one A-10A) lost to enemy fire with 13 additional aircraft lost to "other causes."�  The report notes that the Air Force flew 191 rescue sorties and that space operations reported 40 "Hook Bursts."

"So every time that happened, that means that the national satellite system was receiving â??Hook Bursts' in a way that we were able to act on them," Brady explained. Although unable to be more specific, he observed, "Based on their deployment experiences, a lot of the units returning from the conflict are showing interest in adding the Hook system to their repertoire."

"We can say that our radios helped save lives during Operation Iraqi Freedom," emphasized Patti Gutos, GDDS program manager, combat search and rescue products.�  "And they are continuing to save lives on other missions as well."

The three recent contract orders reflect fielding of the latest CSAR capabilities through both new production and as internal upgrades to older radios. The upgrade, currently costing approximately $5,500 per radio, is still the most cost-effective way of achieving the latest capabilities. However, recent price reductions on new radios - Brady says that a new AN/PRC-112G lists at $6,500 - is prompting an increasing number of customers to target the new product.

Moreover, referring to the GSA contract vehicle now in place, Gutos pointed to recent situations where "some customers have placed orders and received radios within 24 hours. It's that easy to order radios off the GSA schedule."

Along with the introduction of GPS and two-way text messaging, Brady described recent advances in the internal GPS characteristics.

"One distinct advantage that we've recently introduced as a software upgrade to both the B1s and the Gs is the ability to detect GPS interference," he said. "Some [civil] survival radio systems are exclusively based on GPS, which is good. And there are military versions of those radios that are even better. However, any kind of interference to any of those GPS systems can leave a survivor without a real location fix. By detecting the interference level, and characterizing that back to the aircraft or bases, we can resort to other means of closing in on the survivor, such as the capability that has always existed in the 112, the DME capability. That is a GPS independent way of briefly pinging the survivor in a fairly covert way and having his or her radio respond very briefly to close in that manner."

In addition, GDDS engineers have recently demonstrated a Selective Availability Anti-Spoof Module (SAASM) GPS capability operating within the PRC-112G. The new capability retains both SAASM and commercial GPS to allow for the most power effective implementation of GPS positioning. The company is reportedly working to make the capability commercially available early in 2004.

"Another thing that is becoming increasingly important is the use of the Quickdraw interrogator in other platforms, such as UAVs. That provides an opportunity for all sorts of aircraft to give you different angles on the survivor in terms of transmission. Also, if an identification of a survivor is made, we can use vehicles like UAVs to continue with imagery to determine the situation before sending anyone in to rescue the survivor," Brady said.

Brady carefully avoided any comparisons between the Hook2 radios and the emerging CSEL. "Our system is providing the things that the mission requires. So that's why the users are coming back and buying more. And, in making their decision, they are fully aware of whatever other options are available out there," he said.