Domestic air carrier B757 initiates evasive descent due to TCASII alert at FL370 in foreign airspace...

Attributes
ACN	473030
Time
Date	200005
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : tnca.airport
State Reference	FO
Altitude	msl bound lower : 36500 msl bound upper : 37000
Environment
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B757-200
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise : level
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	473030
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : multi engine pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	flight crew : returned to assigned altitude flight crew : took evasive action
Consequence	other
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

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.

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.