Eleven of 30 FAA ATC modernization programs reviewed by the U.S. Government Accountability Office (GAO) have exceeded their initial cost estimates by a total of $4.2 billion, and half have experienced delays.

In a February 16 report to Congress, the GAO declared the FAA’s cost estimation and scheduling practices deficient. Therefore, it said, the FAA cannot provide “reasonable assurances” to Congress and industry stakeholders that ATC programs important to the Next Generation Air Transportation System (NextGen) will avoid further delays and cost overruns.

While the majority of ATC programs reviewed have not increased in cost, the 11 programs that have risen account for more than 60 percent of the total acquisition cost for all 30 programs—or $11 billion of $17.7 billion, the GAO said. The two largest program increases belong to the long-running Wide Area Augmentation System (Waas) deployment, now estimated to cost $3 billion, or three times its initial cost estimate; and the completed Standard Terminal Automation Replacement System (Stars), which increased 189 percent from its original estimate to $2.7 billion. The Enroute Automation Modernization (Eram) program ranks third, running $330 million or 15 percent over budget at $2.48 billion.

Fifteen of the 30 ATC programs have experienced delays ranging from two months at the low end to more than 14 years for Waas. Completion targets for Eram, considered a NextGen “backbone” system, now specify August 2014, nearly four years late.

The GAO focused on four ATC programs to assess the FAA’s cost estimation and scheduling processes: Waas, automatic dependent surveillance-broadcast (ADS-B), collaborative air traffic management technologies (CATMT) and system-wide information management (Swim). Waas is both late and over budget, while ADS-B has seen an estimated cost increase of 3 percent. CATMT and Swim are neither late nor over budget, according to the GAO compilation.

While each of the four programs demonstrated “characteristics” of high-quality and reliable cost estimates, none could produce a “reliable” approximation, the GAO said. Further, the estimates lack “credibility,” largely because the FAA did not obtain independent cost assessments. It classified the four program schedules similarly “unreliable” because none of the programs met or substantially met nine “best practices” for schedule development.

The use of unreliable metrics for individual programs puts at risk the development of an integrated NextGen master schedule and threatens to disrupt NextGen itself, the GAO advised. “The interdependencies of ATC acquisition programs have become more prominent as the NextGen program shifts from planning to implementation, so that cost increases and schedule delays in one program could have a cascading effect on other programs,” the agency said.