Pentagon setting guidelines for aircraft interoperability.

As the number and types of unmanned aircraft continues to grow in the U.S. military services, the Pentagon is pushing the notion that, even though there is no common operating system, UAVs should have standard interfaces so they can interact with each other, Given the diversity of UAV sizes and capabilities, the Pentagon is eschewing a one-size-fits-all approach in favor of common interfaces for specific classes of UAVs, said Dyke Weatherington, deputy of the UAV planning task force at the Office of the Secretary of Defense.

"Certainly in the next two or three years, you'll see some air vehicle interfaces," Weatherington told National Defense. "We're focusing first on defining a standard air vehicle interface for all small UAVs." Small UAVs are first in line because of the ease of receiving data from them, the large number of potential users and the airspace issues that could arise from hordes of organic squad-level UAVs.

The department is working on four general categories of interfaces within a given UAV class:

* Situational awareness. This offers the most basic data for a common operational picture. It will say, "What UAV am I? Where am I going? What sensors am I carrying? What weapons am I carrying? Who owns me? And how do you task me?"

* Payload. The interface will display data and allow control of payload such as sensors, communications, and self-protection. "We'll probably have one interface for electro-optical infrared remote, an interface for radars, an interface for still-framing systems and an interface for signals intelligence systems," Weatherington said.

* A weapons interface. For security and other reasons, weapons need their own interface.

* Air vehicle control. The highest-level interface, this one will allow users to directly control the UAV and its critical subsystems.

Payload interfaces have been fairly well defined at this point, said Weatherington. That's partly because of the work organizations such as the National Security Agency have done in defining standards for UAV equipment for imagery and signals intelligence.

NATO agreements have codified standards for the moving target indicator and other data. But standards and interfaces for vehicle control are fuzzier because the vehicles are evolving so rapidly.

Different classes of UAVs will have similar but not identical interfaces. For example, small UAVs probably will not have a weapons interface, noted Weatherington. Interfaces for small UAVs also will be designed to work the sort of control stations, such as laptops and PDAs, likely to be found at the squad level.

Yet there is also a good chance that PDAs will be able to receive data from large vehicles such as Predator B and Global Hawk, Weatherington said. He cited a recent demonstration that connected a Global Hawk, a surrogate for a Fire Scout and a user on the ground with a PDA-like device.

Lack of UAV interoperability has had a real-life impact on U.S. operations, he explained. "There have been cases where a service's UAV, if it could have gotten data to another service, another component, it may have provided better situational awareness on a specific threat its a specific area that might have resulted in different measures being taken."

As an example of current difficulties, he cited Predator, which is controlled by operators based in the United States. Data are relayed from the UAV to the United States, and then sent back to air operations centers in the theater.

"Predator has significant capability to support troops on the ground, but the architecture that was put together at the time didn't really address that issue," Weatherington noted. He estimated that giving users a common and direct link with Predator might save them 30 minutes to an hour in receiving data, depending on data size and bandwidth.

As for the Navy's troubled tactical control system (TCS), which is supposed to be a common control system for Navy UAVs, Weatherington said the program is evolving.

"The issue with TCS at the time it was created was that there were not sufficient software solutions and interfaces to support a software-only capability. So the program was forced to build in a lot of hardware interfaces that limited the flexibility of the system," he said.

While Congress recommended killing the program last summer, work continues.

Weatherington endorses the Defense Department taking the lead on UAV interoperability, and denies there is institutional resistance on the part of the services. "By and large," he pointed out, "I think it's the department that's carrying the flag for this. At the service level, each of the services buys capability for a specific mission. To some extent, the services say, 'I've paid for my requirements. Why should I pay for stuff that will be used by somebody else?'"

When it comes to interoperability, "we can do better," he said. "We have not procured large numbers yet, so we have an opportunity if we build interoperability in from the beginning. It can dramatically increase capability to a broad class of users and we can potentially reduce force structures."

Weatherington pointed optimistically to several interoperability programs, such as the effort to develop a common operating system for the joint-unmanned combat air systems (See related story). Then there are is the Army's future combat system (FCS) of unmanned ground vehicles. "We are doing heavy analysis as to how much FCS is doing that might support J-UCAS," Weatherington said.

The Air Force and Navy are also working to define common interfaces for Global Hawk. The problem is the size of the ground station. "When the Navy employs it on a carrier, the hardware configuration has got to change. They just can't stick that big box on a ship, so they're going to have to integrate it into the ship. But what we'd like to do is have the data interface to the ground control station to be the same," he said.