ADS-B surveillance and some TCAS operations in the airspace over Virginia, North and South Carolina, Georgia and Florida might become unreliable as of September 2 at 1 a.m. EDT, according to a Notam the FAA issued on September 1. The outages are due to events the agency labeled as “late notice from the Department of Defense of military exercises.” NBAA "voiced its concern to the FAA that these sort of significant impact tests need much more notice to operators in the National Airspace System."

The outages are scheduled to last until midnight October 1. In addition to the areas of concern noted in domestic airspace, the FAA said the outages might well extend up to 200-nm offshore.

The agency said one outage symptom could be the tracks of nearby aircraft first appearing close to the primary aircraft that immediately switch to a traffic alert/resolution alert status on TCAS. Pilots should maintain a heightened watch on the airspace around them and report any incidents of nearby aircraft they believe should have generated alerts, but did not. The relevant Notam numbers are 5/2817, 5/2818, 5/2819, 5/2820 and 5/2834.

In an update released on September 4, the FAA said, “No pilots have reported anomalies with TCAS or ADS-B attributed to similar military activities the FAA has supported in the past. The FAA considers the likelihood of any potential anomalies to be extremely remote, but has established protocols to mitigate the effects, should they occur. The FAA’s radar systems in the area are not affected by the military activity, and air traffic controllers will continue to provide safe separation of aircraft, as they normally do.”

In addition, NBAA said it expects the blanket 30-day Notam "will be withdrawn and more tailored Notams will be issued for smaller windows of time that will also more clearly state that anomalies with TCAS or ADS-B are extremely unlikely but nonetheless provide reporting instructions should pilots encounter any issues." In addition, the FAA said it has communications in place to request the military immediately cease any electronic exercise activities if an anomaly is reported.

[Updated September 4 at 12:26 p.m. ET to include new FAA statement and additional information from NBAA]