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Pilot survey shows WAAS enhances access, safetyPilot survey shows WAAS enhances access, safety

A large majority of pilots who used the Wide Area Augmentation System (WAAS) in IFR operations between 2009 and 2013 strongly agree that the technology, which enhances the quality of GPS, improved their flights, based on responses to an AOPA WAAS usage survey completed in May.
Satellite-based navigation is becoming the norm. iStock photo.

About 80 percent of respondents agreed or strongly agreed that the safety, access, and performance benefits that WAAS provides outweigh the cost of the equipment. A slightly higher percentage said WAAS accuracy was "at least as good as promised by the FAA."

AOPA received a total of 1,129 responses to the WAAS usage survey, which concluded May 20.

“AOPA has been very supportive of WAAS and will share the survey data with the FAA WAAS Program Operational Implementation Team so they can use the data to further improve the system based on this user feedback,” said Rune Duke, AOPA director of airspace and air traffic. “GPS is important and we want it to be improved and expanded per users’ wishes. We need to make sure it is resilient, and that there is a plan for when it is unavailable.”

WAAS’s ability to increase access to airports and airspace was broadly endorsed by respondents—especially where GPS approaches include localizer performance with vertical guidance (LPV).  According to the FAA, there are now 3,678 WAAS/LPV approach procedures serving 1,790 airports, of which 1,041 airports do not have an instrument landing system (ILS) approach. In March 2016, AOPA estimated that about 80 percent of active general aviation IFR aircraft were WAAS/LPV-equipped.

About 88 percent of survey respondents agreed or strongly agreed with the statement that “at night, the WAAS vertical guidance on final approach enhances safety.”

Respondents weighed the cost benefits of WAAS across a range of measures, registering generally positive assessments of the technology’s capability to reduce overall flight time, terminal flight time, and time on approach; and cut operational costs.

With many pilots still relying on VOR as their go-to backup navigation system in the event of a GPS outrage, users expressed concerns about the reduction of the number of VORs in operation as the satellite-based air traffic system modernization proceeds.

Although about 94 percent of the 842 respondents who addressed the issue in the survey agreed that WAAS provides advantages over VOR and other ground-based systems, only about 65 percent believed that WAAS-equipped aircraft would likely no longer use VOR. A similar percentage embraced the idea that “if everyone had WAAS, the FAA could reduce VOR without negatively impacting flight operations.”

AOPA remains “very engaged” with the FAA in advocating for a long-term sustainment plan for the aging VORs, about 94 percent of which are more than 30 years old, Duke said. A nominal network of VORs known as the Minimum Operational Network will be maintained to allow IFR aircraft to navigate in the event of a GPS outage, as explained in AOPA's fact sheet.

The survey also measured users’ impressions of the extent of GPS outages, with slightly more than 89 percent saying outages were “rare or never happen.” In a separate survey on GPS interference conducted in the fall of 2015 with the Canadian Owners and Pilots Association, 21 percent of respondents reported having experienced a complete or partial loss of RNAV capability while using an IFR-certified GPS. Of those, 44 percent had only the single occurrence in the prior 12 months; the remaining pilots reported multiple interruptions.

When there was a loss of GPS, 66 percent of pilots relied solely on VOR as their backup navigation system.

Pilots are encouraged to report the GPS service interruptions they experience to air traffic control, and to share their reports with AOPA. According to the joint AOPA/COPA GPS interference survey, more than 74 percent of pilots neither filed a report nor advised ATC of the problem encountered.

AOPA tracks GPS jamming and interference events and is advocating for sufficient warning being provided to pilots,” Duke said. 

Dan Namowitz

Dan Namowitz

Associate Editor Web
Associate Editor Web Dan Namowitz has been writing for AOPA in a variety of capacities since 1991. He has been a flight instructor since 1990 and is 30-year AOPA member.
Topics: Advocacy, Airspace, Aircraft

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