F-35: CATBird Completes SDD Missions

Code One Header

For more than a decade, the Cooperative Avionics Test Bed (more commonly known as CATB or CATBird), has been the test platform for all F-35 software upgrades before the updates are released to the global F-35 fleet. Now, after 707 flights totaling nearly 2,070 flight hours, the F-35’s flying testbed has completed flights for the System Development and Demonstration, or SDD, phase of the program.

From the outside, this flying test lab would likely never be confused for a typical Boeing 737, with its pointed radome, specialized canards and bold, CATB lettering on the vertical tail. However, it’s the human and computer brainpower inside this aircraft that sets it apart.

“Inside, we have an F-35 cockpit, which a pilot or an engineer can fly in,” said J.D. McFarlan, Lockheed Martin Aeronautics vice president for F-35 flight test and verification. “It has the panoramic cockpit display that sees what all the sensors are doing and sees what the software is doing from a fusion standpoint. Behind the pilot, we have stations for every single subject matter expert and all the engineers to track mission systems software in real-time.”

CATBird’s primary focus has always been validating and testing mission systems software, which affords a pilot greater situational awareness. For the F-35, this includes the APG-81 active electronically scanned array radar; electronic warfare; an integrated communications, navigation, and identification system; the integrated core processor; the electro-optical targeting sensor; the electro-optical distributed aperture system, and the pilot’s helmet-mounted display.

Hardware identical to that of the F-35 is found externally and internally on CATBird. The nose of this flying lab contains the active electronically scanned array radar and the front top sensor and two side sensors for the distributed aperture system, or DAS.

Designated the AN/AAQ-37, DAS consists of six electro-optical sensors placed at various locations on the outside of the aircraft. The system, developed by Northrop Grumman, provides situational awareness in a 360-degree spherical field around the aircraft. As such, it warns the pilot of incoming aircraft and missile threats and provides day/night vision, fire control capability, and precision tracking of wingmen and friendly aircraft for tactical maneuvering.

A Look Inside CATB A look into the CATBird: engineers track critical software capabilities in simulated missions and make in-flight updates.

Typical CATBird missions last about four or five hours, and carries up twenty engineers who are focused on analyzing these F-35 software capabilities and ensuring their seamless execution with the pilot and other software systems.

CATBird is a unique test asset. Although F-35 software testing has been completed for now, this flying laboratory can be adapted to support other test programs. Its likely future will include supporting several programs at the Lockheed Martin Skunk Works in Palmdale, California.

CATBird History  

Testbeds are regularly called upon to simulate complex software and machinery. Convair used a modified T-29 in the late 1950s to support development of the fire control system for the F-102 Delta Dagger. In the 1990s, the Lockheed Martin-Boeing F-22 team flew a modified 757 during development of the Raptor’s systems.

The F-35 Missions Systems team identified the need for an advanced testbed in the early 2000s. CATBird, which started out as a Lufthansa airliner, underwent extensive transformation and testing in the Mojave Desert to prepare for its career in F-35 flight testing.

“CATBird’s first flight stands out vividly when you think about the amount of work in design, analysis, build, and test of the external modifications which include a nose extension housing for the Electro-Optical Targeting Sensor system, radar system, and the actual F-35 production radome, along with other modifications such as the aft strakes, sensor wings, spine, and canoe,” J.D. McFarlan, Lockheed Martin Aeronautics vice president for F-35 flight test and verification, said.

The twenty-seven foot dorsal spine and ventral canoe on CATBird’s fuselage each contain two of the six on-board Distributed Aperture System sensors, antennas associated with UHF, VHF, and satellite communications, as well as several datalinks that enhance test pilot situational awareness. One of these is the F-35 multifunctional advanced datalink, which allows fellow F-35s to share a common view of the battlespace.

Typical missions for the CATBird include sorties like working with land-based, sea-based or other air-based units to simulate how the F-35’s communications networks and radar systems interact with others in the battlefield environment. During these tests, the on-board engineers monitor their assigned software systems and can make real-time changes and upgrades.

For instance, in October 2015, CATBird was flown during the Development Test II (DT-II) trials of the F-35C for the US Navy. CATB was used to test the Joint Precision Approach and Landing System, or JPALS, which is the system F-35s will use to communicate with Navy carriers to ensure precise approaches and landings.

CAB Makes Approach above USS Eisenhower
The CATBird makes an approach above the USS Dwight D. Eisenhower (CVN-69) to test the capabilities of JPALS during DT-II testing

The CATBird crew made an approach simulating that of an F-35, and the results allowed systems engineers to make software adjustments that will improve the capabilities of the F-35C for US Navy and Marine Corps pilots in the carrier’s landing pattern.

“CATBird has been an outstanding platform for us to test mission systems software, and it’s allowed us to deliver a better product to flight test than had we not had it,” McFarlan said.

Written by Amy Cochrum, a Marketing Communications Specialist at Lockheed Martin. This is her first article for Code One.