Narrative:

Flight between dallas and caracas over aruba at FL370, received a TCASII TA, followed immediately by a descend advisory. Captain immediately disconnected the autoplt and initiated a descent of approximately 1500 vsi. Traffic was acquired visually and a monitor vertical speed advisory was received. When the traffic was clear, returned to FL370. During the maneuver we lost approximately 500 ft. ATC was notified and advised us that he did not know the traffic was in the area.

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Original NASA ASRS Text

Title: DOMESTIC ACR B757 INITIATES EVASIVE DSCNT DUE TO TCASII ALERT AT FL370 IN FOREIGN AIRSPACE.

Narrative: FLT BTWN DALLAS AND CARACAS OVER ARUBA AT FL370, RECEIVED A TCASII TA, FOLLOWED IMMEDIATELY BY A DSND ADVISORY. CAPT IMMEDIATELY DISCONNECTED THE AUTOPLT AND INITIATED A DSCNT OF APPROX 1500 VSI. TFC WAS ACQUIRED VISUALLY AND A MONITOR VERT SPD ADVISORY WAS RECEIVED. WHEN THE TFC WAS CLR, RETURNED TO FL370. DURING THE MANEUVER WE LOST APPROX 500 FT. ATC WAS NOTIFIED AND ADVISED US THAT HE DID NOT KNOW THE TFC WAS IN THE AREA.

Data retrieved from NASA's ASRS site as of July 2007 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.