The largest and costliest network to be replaced is the Leased Interfacility National Airspace System Communications System (LINCS) formerly operated by MCI WorldCom but now run by Verizon Communications Inc. FTI is considered a mission-critical program because its network will carry the National Airspace System's telecommunications services, which include voice and radar, for air traffic control operations, according to the report. These services are carried on the LINCS network. When completed, FTI will consist of about 25,000 telecommunications services at more than 4,400 FAA sites, the report said.

Alves said the FTI is a "high-risk" and "schedule-driven" program that is unlikely to meet its December 2007 revised completion date. In fact, only months after being revised in December 2004, the program again began falling behind schedule and has not recovered, he said.

"FTI is not likely to be completed on time because the [FAA] did not direct the program office to develop a detailed realistic master schedule or an effective transition plan identifying when each site and service will be accepted, when services will be cut over to FTI, and when existing services will be disconnected," Alves said. "Further, the program office needs to ensure better coordination with its field offices and with Verizon in order to ensure that service disruptions are avoided when services are transitioned to FTI."

Alves said that until the FAA develops a realistic schedule and effective transition plan, it will be difficult to hold the FTI contractor accountable or determine when the FTI transition will be completed. In addition, the FAA can't accurately estimate how long Verizon's LINCS services will be needed until it has a realistic schedule, he said. To account for the delays to date, the FAA will have to exercise its one-year option to extend Verizon's contract to support the LINCS services but may also need to retain Verizon's services for a longer period, he said.

The FAA had disconnected only about 3 percent of the legacy circuits by the end of fiscal year 2005 and had accumulated a large backlog of uncompleted work, the report said. As a result, the FAA lost out on $32.6 million in reduced operating costs, the report said.