Incident Overview
On 31 January 2008 at 13:30 UTC, a Boeing B-767 operated by Belair Airlines, AG (registration HB-ISE) and a USAF KC-135 (call sign BLEU-83) experienced a potential loss of separation at position N37º53’ W017º56’ in the Santa Maria Oceanic Control Area (OCA). The incident occurred during cruise phase of a scheduled flight from Zurich (LSZH) to Punta Cana (MDPC). There were no injuries or fatalities, and neither aircraft sustained damage.
Sequence of Events
At 13:13, flight BHP-1914 (the B-767) reported waypoint GUNTI, maintaining FL350. At 13:18:20, Santa Maria received a communication from BLUE-83 indicating it was leveling at FL350. At 13:29:50, Santa Maria instructed BLUE-83 to descend to FL345. BLUE-83 replied that it was climbing back to FL345 after responding to a TCAS RA (DESC). BHP-1914 confirmed it had responded to a TCAS RA (CLIMB) and climbed to FL355. At 13:29, the two aircraft crossed with a horizontal separation of 1 NM and vertical separation of 1,000 feet.
Weather and Communications
Weather in the area was good, with a high-pressure area north of the Azores and no significant phenomena. However, high-frequency radio communications were difficult due to atmospheric interference, which affected coordination between the aircraft and Santa Maria.
Outcome
Both aircraft responded promptly to TCAS resolution advisories and re-established safe separation. No damage or injuries occurred. The incident was reported by both the Swiss BFU and NAV, E.P..