Narrative:

Enroute; at 34000 feet flying up the italian peninsula in italian airspace we were having great difficulty hearing center because of background noise. As pilot flying; I was helping the pilot monitoring by inserting new frequencies. There was much chatter on guard frequency. Guard frequency was so distracting both pilots were turning off the receiver for guard to better hear center. All of us discussed the communication threat we were experiencing. I took a 10-minute break. The fourth pilot was in my seat and the first officer remained working the radios. When I returned and was getting briefed; I noted what I first thought were balloons; then drones or possibly uav's. They did not appear on TCAS. They came from below and passed below our left wing. While considering what this was; the pilot monitoring realized the guard frequency had not been regained contact with ATC. They said we had been intercepted.after we regained contact; the two objects I had seen before were now off our left wing; and they peeled off in descending turns away from the aircraft. It is difficult to estimate how distant they were. We had no ACARS message or satcom call alerting us to our loss of communication. I estimate our loss of communication was about 10 minutes. No aircraft used ICAO procedures for intercept. It is possible the targets I saw were fighters who were observing our flight. ATC radio was difficult to hear and congestion on 121.5 caused both pilots to silence 121.5 to hear center. I suggest expand the use of cpdlc (controller pilot datalink communication).

Related reports:

Google
 

Original NASA ASRS Text

Title: A330 Captain reported they lost communication with ATC and did not realize it until they observed unidentifiable traffic near their aircraft.

Narrative: Enroute; at 34000 feet flying up the Italian peninsula in Italian airspace we were having great difficulty hearing center because of background noise. As Pilot Flying; I was helping the Pilot Monitoring by inserting new frequencies. There was much chatter on guard frequency. Guard frequency was so distracting both pilots were turning off the receiver for guard to better hear Center. All of us discussed the communication threat we were experiencing. I took a 10-minute break. The fourth pilot was in my seat and the First Officer remained working the radios. When I returned and was getting briefed; I noted what I first thought were balloons; then drones or possibly UAV's. They did not appear on TCAS. They came from below and passed below our left wing. While considering what this was; the Pilot monitoring realized the guard frequency had not been regained contact with ATC. They said we had been intercepted.After we regained contact; the two objects I had seen before were now off our left wing; and they peeled off in descending turns away from the aircraft. It is difficult to estimate how distant they were. We had no ACARS message or SATCOM call alerting us to our loss of communication. I estimate our loss of communication was about 10 minutes. No aircraft used ICAO procedures for intercept. It is possible the targets I saw were fighters who were observing our flight. ATC radio was difficult to hear and congestion on 121.5 caused both pilots to silence 121.5 to hear center. I suggest expand the use of CPDLC (Controller Pilot DataLink Communication).

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.