Tokyo ARTCC controller lost separation between en route and descending aircraft.

Attributes
ACN	578113
Time
Date	200303
Day	Fri
Local Time Of Day	1801 To 2400
Place
State Reference	FO
Altitude	msl bound lower : 35200 msl bound upper : 35600
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B747-400
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 210 flight time total : 24000 flight time type : 3000
ASRS Report	578113
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : published procedure
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	controller : issued new clearance flight crew : took evasive action
Miss Distance	horizontal : 18000 vertical : 200
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Departed rjaa for zspd about kcc VOR, request return to rjaa per dispatch for #4 engine fuel filter light. Tokyo control issued instructions turn left heading 110 degrees. After heading 110 degrees for several mins we requested lower. We were issued descent to FL330. Began descent from FL390 to FL330. Tokyo control issued frequency change. Contacted tokyo control on new frequency and reported on leaving FL360 for FL330. Controller was very, very busy. At FL352 we got TA and TCASII showed traffic 200 ft below level at FL350 about 5 mi. On our trajectory and descent rate it appeared we would not descend below traffic in time. Captain called tokyo and said, 'aircraft X we have traffic.' tokyo control said, 'aircraft X descend, aircraft X descend.' captain stated we have traffic in sight we must deviate from our altitude and heading. We climbed back to FL356 and turned as traffic passed off of our right at FL350. Traffic appeared to be within 3 mi and 200 ft.

Original NASA ASRS Text

Title: TOKYO ARTCC CTLR LOST SEPARATION BTWN ENRTE AND DSNDING ACFT.

Narrative: DEPARTED RJAA FOR ZSPD ABOUT KCC VOR, REQUEST RETURN TO RJAA PER DISPATCH FOR #4 ENG FUEL FILTER LIGHT. TOKYO CTL ISSUED INSTRUCTIONS TURN L HEADING 110 DEGS. AFTER HEADING 110 DEGS FOR SEVERAL MINS WE REQUESTED LOWER. WE WERE ISSUED DSCNT TO FL330. BEGAN DSCNT FROM FL390 TO FL330. TOKYO CTL ISSUED FREQ CHANGE. CONTACTED TOKYO CTL ON NEW FREQ AND RPTED ON LEAVING FL360 FOR FL330. CTLR WAS VERY, VERY BUSY. AT FL352 WE GOT TA AND TCASII SHOWED TFC 200 FT BELOW LEVEL AT FL350 ABOUT 5 MI. ON OUR TRAJECTORY AND DSCNT RATE IT APPEARED WE WOULD NOT DSND BELOW TFC IN TIME. CAPT CALLED TOKYO AND SAID, 'ACFT X WE HAVE TFC.' TOKYO CTL SAID, 'ACFT X DSND, ACFT X DSND.' CAPT STATED WE HAVE TFC IN SIGHT WE MUST DEVIATE FROM OUR ALT AND HEADING. WE CLBED BACK TO FL356 AND TURNED AS TFC PASSED OFF OF OUR R AT FL350. TFC APPEARED TO BE WITHIN 3 MI AND 200 FT.

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.