Greece and Turkey clash over overlapping military exercise NOTAMs in the central Aegean

Turkey issued NOTAM A3788/26, reserving five large areas of the central Aegean along the 25th meridian for military exercises running from 25 September to 27 October 2026. The notice covers six air routes and describes planned activity including search and rescue and environmental protection missions, with the designated zones in places touching or entering airspace Greece claims as national airspace.

Athens responded with a counter-NOTAM rejecting the Turkish notice, arguing Turkey has no authority to issue air notices inside the Athens Flight Information Region (FIR), the airspace within which Greece provides air traffic services over large stretches of international airspace over the Aegean. Greece then issued NOTAM A3595/26, announcing its own combined air and naval exercises from 12 to 20 October 2026, with two Greek exercise areas overlapping the northern portion of the Turkish-designated zones.

Turkey replied with NOTAM A4388/26, stating it had asked Greek authorities to amend their exercise boundaries because they coincide with Turkish military zones in international airspace. After Athens refused, Ankara declared the Greek NOTAM "null and void" and maintained its own notice remained in force. Greek authorities also reported additional Turkish aircraft and drone violations of Greek airspace and the Athens FIR on 22 September.

At the core of the standoff is who controls the Athens FIR. Greece contends Turkey has no authority to unilaterally reserve airspace or issue NOTAMs within the FIR, while Turkey argues the overlapping zones sit in international airspace rather than under exclusive Greek control. Neither side has withdrawn its notice, and the two sides have effectively scheduled simultaneous military activity in the same areas for the 12-20 October period.

Disputed sovereignty over an FIR is not new in itself, but this case shows how it plays out operationally: two states each issuing a notice that cancels the other's legal standing over the same volume of airspace, with no third-party mechanism resolving which one governs flight planning in practice. Airlines and military planners routing through or near the central Aegean during 12-20 October now face two competing, mutually exclusive NOTAMs covering overlapping zones rather than a single authoritative source.

FIRs are an air traffic service designation, not a sovereignty boundary, which is precisely what lets both governments argue a consistent legal position while scheduling conflicting activity in the same airspace. Whether the overlap produces an operational incident, or simply two parallel exercises that never actually intersect in time and altitude, depends on how each side manages its own aircraft and drone activity during the overlapping window.

The next dated marker is the 12-20 October period itself, when both nations' declared exercises are scheduled to run concurrently over the contested zones. Whether either side amends or withdraws its NOTAM before then, and whether further aircraft or drone incursions are reported in the interim, will indicate whether this remains a paper dispute or escalates operationally.