As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING TRAINING FLIGHT IN PREPARATION FOR TRAINING APPROACH , PILOT HAD STRONG BACKGROUND NOISE INTERMITTENTLY , BECAUSE OF THAT COMMUNICATION BETWEEN CREW MEMBER WAS VERY DEGRADED , MISSION WAS ABORTED AND A/C RETURNED TO BASE AND LANDED SAFELY.