B737 captain expressed concern regarding conflict at FL350 while transiting havana airspace.

Attributes
ACN	613875
Time
Date	200404
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : muha.tracon
State Reference	FO
Altitude	msl single value : 35000
Aircraft 1
Controlling Facilities	artcc : muha.artcc
Operator	common carrier : air carrier
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : mia.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	613875
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	controller : issued new clearance flight crew : took precautionary avoidance action
Miss Distance	horizontal : 700 vertical : 800
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	Ambiguous

Narrative:

We were level at FL350. I noticed an aircraft on TCASII climbing 2000 ft below us, immediately in front of us. At 1500 ft below us, I initiated a call to ATC, asking about the traffic. Havana told air carrier Y to descend to FL310 when they were 1000 ft below us. (I picked up visual contact at that time, the aircraft was approximately 200-300 yards ahead of us, climbing.) at the same time we received a TA. The aircraft closed to 800 ft below us before initiating a descent.

Original NASA ASRS Text

Title: B737 CAPT EXPRESSED CONCERN REGARDING CONFLICT AT FL350 WHILE TRANSITING HAVANA AIRSPACE.

Narrative: WE WERE LEVEL AT FL350. I NOTICED AN ACFT ON TCASII CLBING 2000 FT BELOW US, IMMEDIATELY IN FRONT OF US. AT 1500 FT BELOW US, I INITIATED A CALL TO ATC, ASKING ABOUT THE TFC. HAVANA TOLD ACR Y TO DSND TO FL310 WHEN THEY WERE 1000 FT BELOW US. (I PICKED UP VISUAL CONTACT AT THAT TIME, THE ACFT WAS APPROX 200-300 YARDS AHEAD OF US, CLBING.) AT THE SAME TIME WE RECEIVED A TA. THE ACFT CLOSED TO 800 FT BELOW US BEFORE INITIATING A DSCNT.

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.