Graham Warwick/WASHINGTON DC
The Wide Area Augmentation System (WAAS) can be certificated in 2002 to provide a limited approach guidance capability, the US Federal Aviation Administration has told the aviation community.
But the FAA and prime contractor Raytheon do not yet know if WAAS will ever deliver the planned Category I precision approach capability, they told users at a summit meeting in Washington DC on 15 March.
At the meeting, representatives of the commercial airline and general aviation communities reached agreement to accept an initial level of WAAS service known as lateral and vertical navigation (LNAV/ VNAV). This will provide approach guidance down to a 350ft (107m) decision height, compared with 200ft for Cat I.
LNAV/VNAV will still benefit general aviation, business aviation and regional airlines by providing lower approach minima than available today at most US airports. Downgrading the service provided from Cat I to LNAV/VNAV will make it easier for Raytheon to certificate the WAAS.
The FAA expects to know within two to three months when in 2002 it will be able to certificate the system. But users were told it will be six to nine months before the FAA and Raytheon will know how to get to Cat I - if they can.
The summit was convened after WAAS acceptance testing was halted in January because of excessive false alarms in the integrity monitor. Reducing service from Cat I to LNAV/VNAV will help Raytheon reduce false alarms by increasing the WAAS vertical protection limit (VPL) from 12m to 30m.
Source: Flight International