Along with the return of waterfowl to Alaska, there is another sign of spring: the start of the military training exercise season.  This year’s lead off exercise is Northern Edge, scheduled from May 1-12, including an extended plan for GPS jamming.  An overview of the jamming activities was presented in a briefing to the Alaska Civil Military Aviation Council (ACMAC) recently. These are becoming an increasingly important part of the exercise. Our military uses of GPS, as well as the development of jamming devices by foreign powers, make it an essential component of the “train like we fight” nature of these exercises.  Of course, at the same time civil aviation is becoming reliant on GPS for navigation, and as a key component of the ADS-B system, for surveillance by Air Traffic Control.

Civil Impacts of GPS Jamming
When the military is “testing” their jamming systems, what is the impact on civil aviation?  At the ACMAC meeting, we were informed that the equipment used during the Northern Edge exercise is ground based, operated at two location:  R-2205 east of Eielson Air Force Base, and at Chena Hot Springs.  The jamming will be highly directional in nature, focusing on targets to the north east of those locations.  But be prepared for a shock when you look at the NOTAMs issued regarding these activities.  Even though the plans for jamming are directional in nature, the FAA requires that the NOTAM cover the impact as if jamming was taking place in any direction. Consequently, we end up with projected impacts having a radius of several hundred miles at altitude.

Diagram of the predicted impact of jamming in all directions from the ground locations at R-2205 and Chena Hot Springs. Jamming is planned to take place only to the north east of those locations

Map of potential impacts from GPS testing from NOTAM JFAK 17-01. Please check current NOTAMs before you fly.

The NOTAM issued to warn civil aviation when these exercises are being conducted shows a huge “circle” of airspace that may be impacted, intended to represent an absolute worst case. The actual plans confine the highly directional jamming activities to the north east from the ground locations.  The figures above represents this omni-directional worst case.  At the briefing, FAA advised us that ATC plans to continue to use ADS-B, and to issue clearances for GPS routes and GPS approaches, after cautioning pilots about the activities scheduled during their flight.

Provisions to Cease Jamming
Since the jamming activities can interfere with aircraft navigation, provisions have been made to cease operations should an emergency arise.  ATC will have a direct line of communications to stop jamming and confirm the jammers are off within 60 seconds of receiving the request, in the event of a safety-of-flight issue.  Pilots finding themselves in trouble should contact ATC, in the event of an emergency.

In addition to JPARC airspaces, Northern Edge operations will take place in the Gulf of Alaska, using a corridor between FL220 and 260 to transition between areas

Northern Edge
This exercise is massive in scale.  Over 150 aircraft, launching from bases at Eielson, JBER and Anchorage International Airport are scheduled to participate.  The MOAs and Restricted Areas in the JPARC, along with an offshore airspace over the Gulf of Alaska will see action.  While the exercise runs Monday through Friday for the first two weeks of May, no flying is scheduled on the weekends.  There is a daily pattern to the exercises, with the most intensive flying activities taking place from 10 am to noon for the morning mission, with a second window from 5 to about 7:30 pm. Aircraft departing before and recovering after the mission will extend those times by up to an hour on either end of the day.  Please check NOTAMs carefully during these days, as plans sometimes change in response to weather and other factors.

Getting it right
This training is obviously important to maintain our military readiness. Yet it feels like we still need to find a better balance between communicating the potential impacts of the GPS jamming, without interfering with ongoing civil operations in the National Airspace System.  Please pay close attention during these exercises (there will be more to come later in the season) and tell ATC or Flight Service about any problems you encounter with GPS or ADS-B usage that might relate to this activity.  Please also drop AOPA a message at [email protected].