1997-05-15: F.A.A. Operations Centre advised at 2118Z that AAL460
inbound to Toronto (LBPIA) had radio problems and lost communication with the Tower. The pilot squawked 7600 for radio failure and executed a missed approach. The pilot established contact with the Tower again, then lost contact. The pilot elected to squawk 7700 to make sure the Tower was aware they were having problems. The aircraft came around in VFR conditions and landed without incident at 2000Z. A report is being issued due to potential media attention relative to squawk 7700. Ops. impact -- unknown. Supplemental information (from T.S.B. Initial Notification #A97O0070): Inbound to Toronto, the Boeing 757 experienced intermittent difficulties with communications. The crew squawked 7600 and subsequently 7700 before landing without further incident at 1555EDT. Maintenance replaced both the captain's and the co-pilot's microphone relays (P/N BACR
) and returned the aircraft to service. There has not been a recurrence of the problem.