A descending B747-200 flight crew fails to make their leveloff in time to provide the expected vertical separation between their aircraft and a military aircraft assigned one flight level above them 30 mi southeast of den, co.

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Attributes
ACN	473677
Time
Date	200005
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : den.vortac
State Reference	CO
Altitude	msl bound lower : 19000 msl bound upper : 19300
Environment
Flight Conditions	IMC
Weather Elements	Turbulence Thunderstorm
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv.artcc
Operator	common carrier : air carrier
Make Model Name	B747-100
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	descent : intermediate altitude
Route In Use	arrival : on vectors arrival star : dandd
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zdv.artcc
Operator	other
Make Model Name	Military
Operating Under FAR Part	Part 91
Navigation In Use	other vortac
Route In Use	arrival : on vectors enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller military : 0 controller non radar : 11 controller radar : 9 controller supervisory : 0
ASRS Report	473677
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 50 flight time total : 15000 flight time type : 250
ASRS Report	473658
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : undershoot conflict : airborne less severe inflight encounter : weather non adherence : required legal separation non adherence : clearance other anomaly other
Independent Detector	atc equipment : conflict alert aircraft equipment : tcas other controllera
Resolutory Action	controller : issued alert none taken : insufficient time
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 0 vertical : 700
Supplementary
Problem Areas	Aircraft ATC Human Performance Weather Flight Crew Human Performance Airspace Structure
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error Pilot Deviation

Narrative:

B747-200 was issued a clearance by me to FL190. The aircraft was turned left to a 250 degree heading for traffic, other traffic at FL200. After the B747 left FL200 descending I turned the other aircraft back on course. B747 significantly reduced its descent rate and leveled at FL193. 2 1/2 mins after leaving FL200 and being turned on course, and 1 min 10 seconds after leveling at FL193, separation was lost between the B747 and other traffic. Prior to the loss of separation I verified the clearance with the B747. I then reiterated that it was not at pilot's discretion. I advised the pilot of the traffic and asked if he was going to descend. The pilot replied that they were leaving FL192 as lateral separation was lost. Supplemental information from acn 473658: initially on DANDD3 arrival to dfw. Vectored to the west off the arrival. Multiple descent clrncs received. Cleared to descend to FL190 and rejoin arrival routing and dandd with no crossing restrs. First officer's 'B' autoplt flying and altitude select armed for FL190. Below FL200 autoplt captured altitude and gradually reduced descent rate. Also engine anti-ice was selected. #4 engine indicated anti-ice valve did not open. Power was added to open #4 engine anti-ice valve. While descending through FL193 TCASII advised of 1 O'clock position traffic and commanded level or continue descent. Autoplt was disconnected and aircraft was flown manually to level at FL190.

Original NASA ASRS Text

Title: A DSNDING B747-200 FLC FAILS TO MAKE THEIR LEVELOFF IN TIME TO PROVIDE THE EXPECTED VERT SEPARATION BTWN THEIR ACFT AND A MIL ACFT ASSIGNED ONE FLT LEVEL ABOVE THEM 30 MI SE OF DEN, CO.

Narrative: B747-200 WAS ISSUED A CLRNC BY ME TO FL190. THE ACFT WAS TURNED L TO A 250 DEG HDG FOR TFC, OTHER TFC AT FL200. AFTER THE B747 LEFT FL200 DSNDING I TURNED THE OTHER ACFT BACK ON COURSE. B747 SIGNIFICANTLY REDUCED ITS DSCNT RATE AND LEVELED AT FL193. 2 1/2 MINS AFTER LEAVING FL200 AND BEING TURNED ON COURSE, AND 1 MIN 10 SECONDS AFTER LEVELING AT FL193, SEPARATION WAS LOST BTWN THE B747 AND OTHER TFC. PRIOR TO THE LOSS OF SEPARATION I VERIFIED THE CLRNC WITH THE B747. I THEN REITERATED THAT IT WAS NOT AT PLT'S DISCRETION. I ADVISED THE PLT OF THE TFC AND ASKED IF HE WAS GOING TO DSND. THE PLT REPLIED THAT THEY WERE LEAVING FL192 AS LATERAL SEPARATION WAS LOST. SUPPLEMENTAL INFO FROM ACN 473658: INITIALLY ON DANDD3 ARR TO DFW. VECTORED TO THE W OFF THE ARR. MULTIPLE DSCNT CLRNCS RECEIVED. CLRED TO DSND TO FL190 AND REJOIN ARR ROUTING AND DANDD WITH NO XING RESTRS. FO'S 'B' AUTOPLT FLYING AND ALT SELECT ARMED FOR FL190. BELOW FL200 AUTOPLT CAPTURED ALT AND GRADUALLY REDUCED DSCNT RATE. ALSO ENG ANTI-ICE WAS SELECTED. #4 ENG INDICATED ANTI-ICE VALVE DID NOT OPEN. PWR WAS ADDED TO OPEN #4 ENG ANTI-ICE VALVE. WHILE DSNDING THROUGH FL193 TCASII ADVISED OF 1 O'CLOCK POS TFC AND COMMANDED LEVEL OR CONTINUE DSCNT. AUTOPLT WAS DISCONNECTED AND ACFT WAS FLOWN MANUALLY TO LEVEL AT FL190.

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.