B737 at FL310 with ZNY experienced TCAS TA with opposite dir traffic who responded to TCAS RA.

Attributes
ACN	747651
Time
Date	200707
Place
Locale Reference	airport : psb.airport
State Reference	PA
Altitude	msl single value : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zny.artcc
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	cruise : level cruise : enroute altitude change
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zny.artcc
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	747651
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	conflict : airborne critical
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	flight crew : took evasive action
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance

Narrative:

This may be ATC error. Jul/xa/07; aircraft X; WX-clear. The incident happened just northeast of psb; direct to dny; FL310; ZNY; approximately XA00. During cruise flight at FL310; ZNY gave us an ATC clearance to descend to FL270. The first officer responded to ATC and I set FL270 into the altitude window and rolled down 1000 FPM descent. We descended approximately 200-300 ft when a yellow target first appeared on the TCAS circle. We noted the target was less than 1000 ft below us and closing fast in the opposite direction. Simultaneously; I disconnected the autoplt in anticipation of a TCAS command; and began to stop the descent. Simultaneously; another controller's voice gave us a command to climb to FL310. Simultaneously; the TCAS gave us a 'fly to' command and 'monitor vertical speed.' simultaneously I complied with the TCAS command; and ATC clearance to FL310. The conflict target was an air carrier flight. The air carrier pilot announced the TCAS conflict and RA command. The new york controller admitted he gave us a descent to FL270 and then back to FL310.

Original NASA ASRS Text

Title: B737 AT FL310 WITH ZNY EXPERIENCED TCAS TA WITH OPPOSITE DIR TFC WHO RESPONDED TO TCAS RA.

Narrative: THIS MAY BE ATC ERROR. JUL/XA/07; ACFT X; WX-CLR. THE INCIDENT HAPPENED JUST NE OF PSB; DIRECT TO DNY; FL310; ZNY; APPROX XA00. DURING CRUISE FLT AT FL310; ZNY GAVE US AN ATC CLRNC TO DSND TO FL270. THE FO RESPONDED TO ATC AND I SET FL270 INTO THE ALT WINDOW AND ROLLED DOWN 1000 FPM DSCNT. WE DSNDED APPROX 200-300 FT WHEN A YELLOW TARGET FIRST APPEARED ON THE TCAS CIRCLE. WE NOTED THE TARGET WAS LESS THAN 1000 FT BELOW US AND CLOSING FAST IN THE OPPOSITE DIRECTION. SIMULTANEOUSLY; I DISCONNECTED THE AUTOPLT IN ANTICIPATION OF A TCAS COMMAND; AND BEGAN TO STOP THE DSCNT. SIMULTANEOUSLY; ANOTHER CTLR'S VOICE GAVE US A COMMAND TO CLB TO FL310. SIMULTANEOUSLY; THE TCAS GAVE US A 'FLY TO' COMMAND AND 'MONITOR VERT SPD.' SIMULTANEOUSLY I COMPLIED WITH THE TCAS COMMAND; AND ATC CLRNC TO FL310. THE CONFLICT TARGET WAS AN ACR FLT. THE ACR PLT ANNOUNCED THE TCAS CONFLICT AND RA COMMAND. THE NEW YORK CTLR ADMITTED HE GAVE US A DSCNT TO FL270 AND THEN BACK TO FL310.

Data retrieved from NASA's ASRS site as of January 2009 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.