The decline of the F-111

While the F-111 could (and probably will) serve beyond 2010, it wouldn't be cost-effective to keep upgrading it to serve effectively beyond 2015-2020.
In early-July the RAAF finally responded to persistent criticism of last year's decision to replace the veteran F-111 as early as 2010. It's worth noting that this decision has always been conditional on the upgraded F/A-18 Hornets, together with the RAAF's AP-3C and forthcoming Wedgetail AEW&C and A330 tankers, providing a much enhanced strike capability.

However, a vocal and persistent lobby group has argued against this decision. On July 5 the online newsletter Heads Up published a rebuttal by the Chief of Air Force, AVM Angus Houston, to some of this criticism. ADM has also weighed into this debate, seeking expert advice from both industry and service sources (serving and retired).

For the F-111 the writing began to appear on the wall as long ago as 1990, according to a retired RAAF officer who has flown both Hornets and F-111s. Taking part that year in Ex Pitch Black, and flying a Hornet on this exercise for the first time, he was flying a combat air patrol at high altitude watching out for intruders. He spotted one - an F-111 right down on the deck trying to penetrate the air defence screen at 480kt.

Despite the ground clutter and terrain masking flight profile the Hornet's APG-65 pulse Doppler radar spotted the F-111 far enough away to signal clearly to its pilot that the "Pig" was no longer queen of the skies.

To the Hornet pilot the bottom line was simple: you could no longer send the F-111 into harm's way without a fighter escort or some form of support package. And if the escort couldn't reach a target, the F-111 couldn't bomb it: its legendary payload/range was no longer a dominant factor in its operational effectiveness. By the early 21st century it no longer enjoyed an insuperable advantage over more modern strike aircraft.

In the hands of RAAF aircrews it is still a potent deterrent platform, but is no longer the silver bullet it once was.

Much recent commentary has asserted that the F-111 can and should remain in service far beyond 2020 and that it can remain an effective (and cost-effective), survivable long-range strike platform. Interestingly enough, this assertion appears to enjoy little support among current and recently retired Defence professionals - a sign, perhaps, of the general acceptance within the senior echelons of the service that the F-111 is entering its twilight years.

Notwithstanding the F-111's recent outstanding performance on Ex Red Flag in the US, (which required a massive effort by the RAAF Air Combat group, and in which the aircraft operated with fighter escorts) it is nearing the end of its economical service life. Extending that life may be technically possible, but will the aircraft be able to cope with the advances and unknowns of 2015 to 2040, and beyond? Many doubt the F-111 could ever become capable enough to justify a significant investment; in any case the constraints imposed by the current defence budget would impose major risks; and the lost opportunity costs elsewhere in the defence budget of making such an investment would almost certainly be too high.

Assuming someone were bold enough to try, the investment would have to address some key areas: stealth (or Low Observability, LO); the F-111's age; its reliability; the cost of operating it; and the cost of turning it into a network-enabled strike platform.

This aircraft cannot be made stealthy. Stealth matters, which is why air forces and aerospace manufacturers in the northern hemisphere are investing significant amounts of money in developing and fielding stealthy manned and unmanned aircraft. Responding to media assertions that the F-111 could be made stealthy, Houston's statement to "Heads Up" said: "While the F-111 frontal RCS can be reduced, even small off-boresight angles make the aircraft a significant reflector and its construction does not lend itself to RCS reductions."

Even if you could successfully apply LO characteristics to the F-111 this would require much development work and testing (who would provide the technology, by the way?) and the additional recurring costs involved in maintaining that capability, let alone enhancing it in future, would be significant. And the F-111 would probably still require a fighter escort.

It cannot be made young again. The F-111 is an ageing aircraft. By definition this means it is vulnerable to unpredictable problems which could affect its availability and operational capability. Two such issues - wing cracking and fuel tank problems - have arisen recently, requiring considerable expense and engineering effort to resolve satisfactorily. The F-111 airframe is not immune to similar unforeseen problems, while the systems aboard the aircraft are old as well.

It cannot be made cheaper to operate. This is partly because it is an ageing aircraft. It's also because it was designed in the 1960s with a completely different level of technology. Modern aircraft, while often more complex, are designed to be much more economical to maintain. Australia is also the sole operator of a very small fleet of F-111s - that significant capital investments in upgrades, new test equipment and the like cannot be amortised over a large fleet.

Houston disclosed last month, "There are only 16 F-111C aircraft available. Normal operational serviceability rates for the F-111 would indicate the number of aircraft available for a single strike to be less than 16."

The engineering resources required to implement a rolling upgrade of the F-111 would likely have a distorting effect on the resources available across the rest of the RAAF. Acquiring more ex-USAF airframes and spares also may not be a realistic option as RAAF engineers have already
It cannot be upgraded to deliver anything like the capability required without incurring significant costs and greater risks: the Avionics Upgrade Program of the early-1990s cost about $0.5 billion for just 22 aircraft - and not all of the F-111's avionics were digitised; the AUP program ran late and over budget.

Houston told "Heads Up" that upgrading the F-111 to provide the stand-off weapons capability, the EWSP and the connectivity required by the network-enabled air force of the future is possible, but would be expensive and time-consuming - the AGM-142 missile integration program is a vivid example.

"It is not just the hardware that can be attached to the aircraft," he said. "New electronic equipment needs connection to power, environmental systems (heating and cooling) and the data bus and displays of the aircraft. The equipment also requires extensive software development, integration with existing systems and operational testing.

"As an example, changing radars on the F/A-18 has required changing displays which recognised new integration with other equipment which interacted with that display," Houston said in a rebuttal to other claims the F-111 could be re-equipped with a new radar. "Our experience...indicates that integrating new equipment on the F-111 is extremely expensive and risky."

If the RAAF continues to invest in such upgrades with the current F-111 fleet this will create a small force of very expensive orphans - lacking stealth and requiring a fighter escort, will they endow the ADF with sufficient credible strike capability to justify their retention and the cost and risks inherent in upgrading them?

By Gregor Ferguson, Adelaide