Change introduced for WAAS users gives operational capability close to a Category 1 instrument landing system

The US Federal Aviation Administration is lowering by 50ft (15m) the vertical approach minima for GPS wide-area augmentation system (WAAS) users due to increased performance recorded by the system.

The FAA says the first new WAAS procedures using the lower 200ft minima will be available in 2007.

“This change will enable WAAS vertical guidance procedures to achieve an operational capability similar to an instrument landing system, where suitable airport conditions exist. Those airports that do not have the appropriate conditions may require additional infrastructure and airspace upgrades,” says the FAA.

It adds: “WAAS-equipped commercial operators will gain access to Category 1 equivalent approach services at qualifying airports where there are no instrument landing systems. This will result in improved safety, including enhanced approach and landing operations in marginal weather.”

WAAS was originally intended to provide Cat 1 precision approach capability and a 200ft decision height. Current WAAS procedures support approaches down to 250ft.

The new procedures will usher in the next phase of WAAS development, known as the global navigation satellite system landing system segment, which is due to take place between 2008 and 2013.


Source: Flight International