The U.S. Federal Aviation Administration has advanced airspace adjustment efforts in about a third of the regions designated under its multi-year Optimization of Airspace and Procedures in the Metroplex (OAPM) effort, which the Department of Transportation (DOT) inspector general cited as a program of concern due to its incremental pace and unclear benefits.

The OAPM effort aims to improve air traffic flows in congested “metroplex” regions with multiple airports serving major metropolitan areas. Study teams consisting of FAA and industry representatives identify improvements that can be made in their regions within three years by adjusting airspace sectors and implementing “performance-based” navigation procedures. The study teams then hand off their findings to design and implementation teams.

The OAPM effort involves 21 metropolitan regions over seven years. Last year, studies concluded in five—northern California, southern California, Houston, Atlanta and Charlotte, N.C.—and design activities started in Washington, D.C., and north Texas. Already this year, design work has started in Houston, Atlanta and Charlotte, according to the FAA. The Houston project is “well into the design phase,” and involves United and Southwest airlines, the agency announced April 4. The Atlanta and Charlotte projects involve Delta Air Lines and US Airways.

Authorities consider the success of the OAPM effort in demonstrating near-term benefits such as improving airlines’ on-time performance and reducing fuel consumption vital to convincing stakeholders of the need for longer-term, more expensive investments in technology and procedures required for the Next Generation Air Transportation (NextGen) system. In the FAA’s 2012 NextGen Implementation Plan, released in March, acting Administrator Michael Huerta wrote of “steady and tangible” progress toward NextGen. He cited the OAPM effort in particular.

Last November, the office of DOT Inspector General Calvin Scovel III listed the OAPM effort among “top management challenges” facing the FAA in Fiscal Year 2012. Despite completing several metroplex studies, the FAA “has not established detailed milestones to complete initiatives at high-activity locations or a mechanism to integrate its metroplex initiative with other important initiatives,” the IG stated in the challenges document. “As a result, airspace users are concerned about the pace and execution of the metroplex effort thus far as well as the lack of clearly defined expected benefits.”

In February, a work group of the NextGen Advisory Committee advising the FAA on the OAPM effort produced recommendations on prioritizing metroplex sites and airspace requirements following a year-long study. The work group found “insufficient data currently available for high-fidelity, quantitative evaluations of the benefits, costs and implementation issues associated with deploying specific operational improvements or sets of operational improvements within particular metroplexes.”