The US General Accounting Office (GAO) has slammed the Federal Aviation Administration for poor management of the Wide Area Augmentation System (WAAS) programme. The GAO also warns that the US agency will not be able to deliver even limited WAAS capability until 2003.

"The FAA has historically experienced major difficulties in delivering modernisation projects within cost, schedule and performance parameters, and the WAAS programme has been no exception," says the GAO.

The GAO believes that the FAA could incur $240 million in additional WAAS costs by 2003. WAAS is designed to ensure the accuracy and integrity of signals from the global positioning system (GPS).

The cost estimate has ballooned to $2.9 billion and the September 2000 commissioning date of a limited WAAS capability has slipped to 2002.

FAA officials will not know until December whether the Raytheon-built system will deliver the planned Category 1 capability.

The GAO says the FAA will have to retain about 30% of its ground-based navigation system to address concerns about GPS signal vulnerability and to support users who choose not to switch to WAAS, adding $170 million to annual costs.

The FAA will continue to suffer WAAS delays because "software development-has been the Achilles' heel of the FAA's efforts to deliver programmes on time and within budget", says the GAO.

Kenneth Mead, the US Department of Transportation's inspector-general, says: "Considerable development work will be required to develop the necessary algorithms and software to resolve integrity concerns, and some WAAS components may need to be redesigned."

The FAA admits that it "underestimated the complexity of the integrity problem", but now feels that "adequate technical oversight" is in place.

Source: Flight International