Ground, flight tests yield zero interference for interrogator system

Members of a special E-3 Airborne Warning and Control System testing team pose for a group photo after a flight trial held in Germany last month. The ground and flight tests on a NATO AWACS made strides in proving that the waveforms cause no interference to military and civilian air traffic control. Participants included representation from ESC's 635th Electronic Systems Squadron, Belgium, the European Union, France, Germany, Italy, NATO, the Netherlands, United Kingdom and United States. (Courtesy photo)

Members of a special E-3 Airborne Warning and Control System testing team pose for a group photo after a flight trial held in Germany last month. The ground and flight tests on a NATO AWACS made strides in proving that the waveforms cause no interference to military and civilian air traffic control. Participants included representation from ESC's 635th Electronic Systems Squadron, Belgium, the European Union, France, Germany, Italy, NATO, the Netherlands, United Kingdom and United States. (Courtesy photo)

HANSCOM AIR FORCE BASE, Mass. -- Overseas ground and flight testing on a NATO Airborne Warning and Control System demonstrated that a prototype waveform designed to better distinguish friendly forces from foes did not interfere with European civilian air traffic control. 

This paves the way for the 635th Electronic Systems Squadron to continue developing the capability without having to modify the current design and implementation.

The prototype, referred to as the Mode 5-capable UPX 40, would replace the current Mode 4 capability and has been designed specifically to interfere less with U.S. and international civil air traffic control functions.

"We in the military need to perform our mission, but we also don't want to interfere with civil aviation's ability to maintain safe separations standards of all aircraft operating within the National Airspace System," said Patrick Martone, 635 ELSS lead engineer. "Sometimes those two performance objectives can conflict with each other, but initial analyses of both flight test data and high-fidelity simulations have shown that Mode 5 has no impact on civil air traffic."

The E-3 Sentry Airborne Warning and Control System, or AWACS, is an aircraft with integrated command and control, battle management, surveillance, target detection, and tracking capabilities and provides an accurate, real-time picture of the battlespace to the Joint Air Operations Center.

AWACS' interrogator radiates a waveform, using different modes, to determine information such as aircraft identification and altitude and determines if aircraft are friends or foes -- known as Identification Friend or Foe capability. The AWACS interrogator enables both military and civilian aircraft to be identified with range, bearing, and elevation information, along with providing platform-specific information.

The new Mode 5 capability is a waveform to which the Defense Department and NATO forces are now transitioning.

Ground testing by Eurocontrol - Europe's equivalent to the FAA - included radiating Mode 5 waveforms to evaluate their impact on civil transponders and civil air traffic control systems. The results showed no impact.

This is very important, given that the United States and Europe civil ATC agencies won't allow use of the new military Mode 5 if it is determined to interfere with controllers' ability to maintain aircraft safe separation standards. Civil aviation organizations from Germany, Belgium and the Netherlands also observed these ground and flight test trials in Germany.

Another stride came in the form of coalition interoperability -- demonstrating that Mode 5 waveform works in conjunction with the products other nations are developing. For example, Mode 5 equipment with U.S. origins successfully interoperated with Italian fighter planes equipped with their own Italian-manufactured transponder devices.

"The detailed technical standards can be interpreted differently amongst companies, nations and services," said Capt. Will Williams, Next Generation IFF program manager. "So it's a major milestone to prove that equipment made in the U.S. interoperated with other equipment made outside of the U.S."

Further developing Mode 5 will bring added benefit to the warfighter, primarily by replacing and surpassing Mode 4 in its ability to identify and locate friendly forces. This more reliable IFF system can pinpoint targets in densely packed environments, better eliminating fratricide.

"When we have lots of military aircraft operating in the same small area during an exercise or real-world engagements, IFF Mode 5 will allow AWACS to distinguish specific information about all friendly forces and will also allow us to distinguish friends from foes," Mr. Martone said. "With the legacy Mode 4 capability, it's more difficult to identify and distinguish all friendly and non-friendly aircraft in a densely packed environment."

Mode 5 brings also adds a layer of aircraft-specific information and security not provided by Mode 4.

"With Mode 5, instead of just knowing whether that distant target is a friend or a foe, operators can now know whether the target is an F-15, for example," Mr. Martone said. "The AWACS operator will know other information about each specific friendly target provided within an encrypted reply to an interrogation."

Despite these demonstrated victories, the squadron's work to fine-tune the capability continues through the current Engineering & Manufacturing Development stage in preparation for a production decision in 2011.

Next month the ESC team will participate in the Mode 5 Joint Operational Test Approach, a demonstration event that aims to determine how Mode 5 equipment will interoperate among differing platforms, military services and manufacturers.

JOTA participants include the Navy, Air Force, Army and Marine Corps and each service's respective interrogators and transponders affixed to a range of operational platforms - aircraft, ground vessels and sea surface vessels. Combat scenarios will not only evaluate interoperability, but also the effects on civil air traffic control.

For the 635 ELSS, having AWACS there serves a two-fold purpose - to satisfy operational test and evaluation requirements, but also to prove the reputation as the premier air surveillance platform to be true.

"The idea is to have AWACS there because of its reputation of being the premiere airborne surveillance platform," said Captain Williams. "At JOTA, we get an opportunity to demonstrate this, and use the results to improve the development of our interrogator and move one step closer to providing the warfighter a much needed capability."