The U.S. Air Force's long-held ambitions to modernize old C-130s have survived contractor protests, a procurement scandal and technical problems, but now they are battling new headwinds.

This time, the resistance is coming from the U.S. Congress.

Improvements to the aircraft's communication, navigation, surveillance and air traffic management (CNS/ATM) capabilities are needed for the Lockheed Martin tactical transports to have access to the most preferred and efficient air routes globally. Aircraft lacking certain CNS/ATM equipment are forced to fly at lower altitudes and on less-direct air routes, adding time and cost to missions. The equipment is especially important when flying in congested airspace such as over Europe. The military refers to these requirements as Global Air Traffic Management (GATM). The first set of GATM rules will be implemented next year.

Senate defense authorizers have thwarted the Air Force's plans from last year to pursue a scaled-back C-130 cockpit upgrade instead of a long-standing but stalled effort to field an expensive, holistic Avionics Modernization Program (AMP) package by Boeing. They are backed by the appropriators. A measure included in a fiscal 2014 omnibus spending bill—a bipartisan measure totaling more than $1 trillion in government funding—forbids the service from canceling the Boeing C-130 AMP program of record.

Air Force officials were unable to explain how GATM requirements would affect a C-130 fleet that was denied new equipment, though GATM compliance was part of the original program awarded to Boeing in 2001.

The FAA mandate calls for aircraft to operate with the new Automatic Dependent Surveillance-Broadcast system by January 2020, leaving a tight timeline for any program to work through the complex Pentagon procurement system and become fielded.

The Air Force had terminated the once $5.9 billion Boeing-led C-130 AMP in the fiscal 2013 budget plan, proposing instead a trimmed down project in an effort to save as much as $2.3 billion, according to Gen. (ret.) Norton Schwartz, chief of staff of the Air Force until August 2012. He called the Boeing C-130 AMP program “simply unaffordable.”

But legislators have stunted even the scaled-down plan. In the fiscal 2014 National Defense Authorization Act, signed by President Barack Obama last month, lawmakers prohibit the Air Force from canceling or modifying its C-130 AMP program. And in section 133 of the act, they expressly forbid the service from starting an alternate program, which had been promoted by some leaders seeking a simplified CNS/ATM fix without all the bells and whistles of the Boeing-led effort.

The intent of the language was to steer the Air Force back toward the Boeing solution; the manufacturer has lobbied hard on Capitol Hill for the program, according to a congressional staffer. The final outcome likely will see both C-130 AMP and an alternative stalled pending receipt of a review by the Government Accountability Office, leaving the Air Force without a way ahead for the fleet. That report is expected by April 1, according to Ed Gulick, an Air Force spokesman.

Last year, when the service proposed termination, the authorizers directed USAF to have a third party—the Institute for Defense Analysis—study C-130 modernization options, a move viewed by some as a delaying tactic to preserve the Boeing program. “That study was completed and provided to Congress this fall,” Gulick says. The study advises against pursuing C-130 AMP because lower-cost options exist to produce nearly equivalent capability. “The . . . study recommends the Air Force pursue either of the two scaled-back program options, based on available funding.”

The service had completed the development portion of the Boeing C-130 AMP program, but had not initiated a competition to produce the AMP kits. The previous program called for a contest to select a single competitor to vie for such production work against Boeing. Lockheed Martin, BAE and L-3 Communications are among the companies that could compete for the work. There are also a number of smaller outfits conducting work for foreign C-130 operators who would be in a position to bid for a trimmed-down CNS/ATM fix for the Air Force if the service goes that way. That full-rate production decision was expected in February 2013.

Owing largely to budget cuts—as well as frustrations related to challenges in the Boeing program—the Air Force had embraced the idea of a trimmed-down CNS/ATM program. The AMP project was conceived in the late 1990s, when funding for what some call a “gold-plated” program was readily available and the appetite for capability was insatiable.

At the time, the Air Force viewed AMP as a way to more closely standardize its many different versions of legacy C-130s—at one point 13 variants were in operation—easing maintenance and training requirements for the fleet. Eventually, the Air Force envisioned operating only the AMPed C-130s and the C-130J, the new version now being delivered by Lockheed Martin. A restructuring to the program in 2007 cut aircraft operated by Air Force Special Operations Command and narrowed the scope to upgrades that would include only the H2, H2.5 and H3 variants operated by the Air Force.

But this latest roadblock for the C-130 CNS/ATM problem is hardly the worst. The program was embroiled in a procurement scandal brought on by Darleen Druyun, a former top Air Force procurement official who pled guilty to illegal job talks with Boeing while in the service (these took place shortly before she accepted a civilian post with the company); in 2004, she was sentenced to nine months in prison. Druyun admitted to steering contracts, including C-130 AMP, toward Boeing, which won its development contract in 2001. Thus, USAF was forced to compete production of the kits, an effort that is now stalled.

As the program progressed, however, it was restructured due to ballooning cost; the original plan to modify 519 aircraft was reduced to 222 (now 221 owing to an aircraft loss).

Boeing conducted the first flight of a test C-130 outfitted with AMP in September 2006, and the first five C-130AMP aircraft have been delivered to Little Rock AFB, Ark., says Jennifer Hogan, a Boeing spokeswoman. Three were modified by the manufacturer and two were handled by Robins AFB, Ga., where the C-130 depot is located. A sixth C-130 AMP kit has been delivered to Robins for installation.

Boeing has also delivered two full-motion weapon system trainers to Little Rock.

However, without a last-minute deal, the Air Force is likely to be stalled for years while it sorts out politically palatable paths for the fleet.