More outreach needed before interference events, FAA told

U.S. Department of Defense interference events, designed for training in GPS-denied environments, also can affect civilian aircraft.

In April 2016, a business jet lost all GPS signals because of an interference event and was forced to enter a Dutch Roll, resulting in an emergency descent.

Pilots and air traffic controllers in the National Airspace System want to better understand the operational impacts of the intentional interference, which has risen from 43 in 2012 to 127 in 2017.

Interference Contours from the YPG 17-02 GPS interference event in January 2017. (Source: FAA)

An RTCA Tactical Operations Committee composed of Federal Aviation Administration (FAA) and industry experts in March issued a report with recommendations to change the current Notices to Airmen (NOTAMs).

Along with a description of the event, NOTAMs show contours that represent an area outside of which operators should expect no interference impact. Both operators and the FAA agree that most aircraft experience no interference impact even inside the contours.

Operators recommend that the FAA provide pilots and controllers improved understanding of where to expect interference impacts based on different equipment capabilities, so that operators could integrate such information in their flight planning processes.

Impact varies widely, depending on aircraft, avionics, position, time, location and terrain. Effects could include complete loss of GPS navigation, position errors, loss of ADS-B or impact to GPS-dependent systems.

Operators are encouraging thte FAA to conduct outreach with civil aviation stakeholders around significant interference events so they better understand the impact.

The FAA says it is studying the committee’s 25 recommendations.