One of the F-15C's known shortfalls is its dated cockpit, which includes a spattering of 'steam' gauges, radar scope, radar warning receiver display, and a small color multi-function display. Compared to fighters built even in the latter 1980s, it's archaic. Now it has come to our attention that the USAF has been upgrading their F-15C Eagle's with a large multi-function display that slots in where the F-15C's engine instruments and radar warning receiver were installed. This little talked about enhancement is known as the Passive Attack Display, or PAD.
The Fighter Bomber Directorate at Robins AFB told The War Zone that the upgrade coincided with the introduction of the AN/AAQ-33 Sniper Advanced Targeting Pod to the greater F-15C/D community around 2015. The Sniper integration program for the F-15C is named the Passive Attack Sensor System (PASS).
Designed primarily for strike fighters to surveil and target objects on the ground, the Sniper pod has since migrated to the B-1 and B-52 bomber communities with great success and is largely seen as the standard for targeting pods the world over.
The system packs a mid-wave FLIR, HD television camera, laser spot tracker, laser designator, onboard DVR, and a video data-link. But its greatest assets to the F-15C are its powerful zoom capabilities and its high definition.
Around the turn of the decade, the pod was seen as a possible solution to the F-15C's long-range aerial target identification shortfall. The F-15C/D fleet has non-cooperative target recognition (NCTR) capabilities that utilize the aircraft's radar to identify and classify the unique signature of the targeted aircraft, but these methods are in no way totally reliable, or in some cases, even available depending on a large set of factors.
Even with the ability to kill other aircraft from dozens of miles away, and increasingly capable identification friend or foe (IFF) systems, visual identification has remained the standard rule of engagement for most combat environments over the last few decades. But that doesn't mean the naked eye literally has to see the target by looking out the window.
In fact, over the decades, some F-15 units have attached hunting rifle scopes next to their HUDs in an effort to provide some sort of long-range visual identification capability. The Eagle's Naval counterpart for many decades, the F-14 Tomcat, had a Television Camera Set (TCS) system that was designed specifically for target identification beyond visual range. It was limited to about a ten miles against fighter-sized targets and substantially longer against bombers, making it usable for AIM-7 Sparrow shots.
The need to visually ID targets as quickly as possible and at night is especially crucial for F-15Cs sitting alert in the United States. Air National Guard F-15C/D units are arrayed around all of America's maritime borders, with units in Massachusetts, Florida, Louisiana, California, and Oregon. F-15s sitting alert are called on to intercept all types of targets, in all weather conditions, 24 hours a day, 365 days a year. These targets include everything from wayward light aircraft, to troubled airliners, to aircraft threatening the President's security, to more 'exotic' targets of interest. Being able to ID a target sooner than with the naked eye can mean the difference between a failed or successful enemy attack, and increases situational awareness dramatically not just for Eagle pilots in the air, but also for controllers on the ground that are managing the intercept.
It was the Florida Air National Guard's 125th Fight Wing that pioneered the Sniper pod concept, deeply testing it and devising tactics associated with it before the rest of the F-15C fleet began receiving the $1.6M pods. To our best knowledge, before the PAD was introduced, a tablet was used to display the pod's imagery, which was a workable, but far from an ideal setup.
The pod locks onto aerial targets primarily by slaving its optics to the aircraft's radar. It can also be manually steered, or cued by the pilot's Joint Helmet Mounted Cueing Systems (JHMCS), and has a secondary aerial search function that provides something akin to a 'poor man's' infrared search and track (IRST) functionality. Keep in mind that the Sniper pod is in no way a worthy analog for an actual IRST, which can rapidly detect multiple targets at far greater ranges with its longer wavelength infrared optics. IRSTs can also provide an array of search and track functions, including the ability to provide targeting data for beyond visual range engagements, which can be a huge advantage.
IRSTs can have visual imaging capabilities as well, but not with the high fidelity or versatility of the Sniper pod. You can read all about IRSTs, their capabilities, and the tactics that go along with them in this past special feature of mine.
The F-15C is also slated to receive an IRST which will come in the form of Lockheed's IRST21 encased in the company's Legion Pod, or to a smaller degree, the Talon Hate pod.
Beyond using the Sniper pod just for long-range identification, it can also be used in the non-traditional information, surveillance, and reconnaissance (NTISR) role to rapidly gather data on ground targets. For the Air National Guard, this means that local F-15s can be scrambled during an emergency to begin collecting reconnaissance imagery, including full-motion video, of a particular site or an area. This could be especially useful following a natural disaster, when critical infrastructure fails, or during a terrorist attack. The setup can even be used for drug interdiction efforts.
By 2015, the Sniper pod was arriving in full force at other F-15C units and today the capability is widespread and has regularly deployed overseas with the Eagles. At the same time, the Passive Attack Display program was getting underway.
The introduction of the Sniper pod is just one part of the so-called "Golden Eagle" upgrade path which looks to keep around 179 frontline F-15Cs tactically relevant for years to come. With its new and hugely powerful APG-63V3
AESA radar, Link 16 data-link connectivity, Sniper targeting pod, Advance Display Core Processor (ADCP) II, and more upgrades to come including the aforementioned infrared search and track system, conveying so much information to the pilot in such a dated cockpit is a major problem.
This is where the Passive Attack Display comes in. It gives the Eagle Driver a 9X11 inch night vision compatible, color multi-function display screen with a resolution of 1024X768. It can show multiple video channels and instrumentation feeds, including a number of them at one time, via multiple windows. It also can overlay instrumentation or tactical data on a video feed. You can read the complete RFP for the system here. IEE who makes the display describes it as such:
"The PAD uses an ARINC 818 fiber optic interface to receive video from, and exchange messages with the ADCP II. The ADCP II facilitates the centralization of a number of critical display functions, such as the consolidation of multi-window configurations into one complete screen image for distribution to display units. This addresses the need for the ever-increasing amount of information available to operators to improve situational awareness.
The F15-PAD upgrade features twelve programmable discreet interfaces, each of which can be provisioned by the ADCP II to three different types of inputs and outputs. These discreets can be used for other aircraft functions, giving the PAD a built-in service life extension."
Today, the PAD primarily provides a big display for checking out the Sniper's video feed, monitoring the Eagle's engines, and displaying Radar Warning Receiver (RWR) information.
There was also a planned upgrade to replace the Eagle's RWR and obsolete AN/ALQ-135 Tactical Electronic Warfare System (TEWS) that would have provided a quantum leap in combat capability and survivability for the Cold War era jet. The Eagle Passive/Active Warning Survivability System (EPAWSS) is able to geolocate threat emitters and use various electronic warfare tactics to counter them, allowing the F-15 to penetrate through contested airspace. The system would need to display this info in a situational manner and would have also taken good advantage of this new display, but EPAWSS was recently put on indefinite hold for the F-15C, with just the F-15E Strike Eagle fleet now slated to receive it.
Currently, the air superiority Eagle has a somewhat precarious place in the USAF's arsenal. There is a roadmap being implemented that will see the jet serve well into the 2040s and even beyond, but the flying force still isn't sure just how long it wants to keep it around, and as a result, how much it wants to invest in it.
Some of the jets will need new wings beginning in the mid 2020s. This is an expensive proposition but one that could see the aircraft last for decades longer if executed. Replacement of the notoriously problematic longeron structural beams that run along the F-15's canopy rails is already underway. But if the USAF really plans on keeping the jet in service into the middle of the century then other upgrades like EPAWSS will be essential.
The possibility of retiring the entire F-15C/D fleet and replacing it with upgraded F-16s has been floated by the USAF brass. The recent increase in defense spending and the establishment of a multi-year defense spending bill has certainly helped to abate such a decision from being made at this time. But in the not so distant future, the Air Force will have to come to a verdict as to the F-15C/D's fate one way or another because pouring large sums of money into upgrading an aircraft you may soon retire is clearly a wasteful proposition.
If the mighty Eagle is blessed by the USAF with decades of additional service, an entirely new cockpit layout may be in order. This, along with a new low-profile heads-up display, already exists, with Qatar being the first country to field it in their new-build F-15QAs.
In the meantime, Eagle Drivers can finally enjoy more screen area to work with in their cockpits via the Passive Attack Display.
A special thanks to the public affairs office at Robins AFB for their help in identifying the PAD and understanding its origins.
Contact the author: Tyler@thedrive.com