ZAB controller described separation loss between aircraft descending for phx.

Attributes
ACN	605971
Time
Date	200402
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : zun.vortac
State Reference	NM
Altitude	msl single value : 28000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zab.artcc
Operator	common carrier : air carrier
Make Model Name	B777 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zab.artcc
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller limited radar : 1 controller non radar : 1 controller radar : 12 controller time certified in position1 : 12 controller time certified in position2 : 5
ASRS Report	605971
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	non adherence : required legal separation non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	none taken : insufficient time
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 6000 vertical : 0
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance Aircraft
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Both aircraft were on descent to phx with the B777 8.2 mi in front. Upon leveling at FL280, the B737 began to catch the B777, indicating a +80 KT overtake. The controller queried the B777 as to IAS. The pilot stated he had reduced to 250 IAS although no speed was assigned. The controller told the B777 to increase to +300 KTS and had the B737 reduce to 280 KIAS. More aircraft are reducing speed in descent phase of flight and not advising ATC.

Original NASA ASRS Text

Title: ZAB CTLR DESCRIBED SEPARATION LOSS BTWN ACFT DSNDING FOR PHX.

Narrative: BOTH ACFT WERE ON DSCNT TO PHX WITH THE B777 8.2 MI IN FRONT. UPON LEVELING AT FL280, THE B737 BEGAN TO CATCH THE B777, INDICATING A +80 KT OVERTAKE. THE CTLR QUERIED THE B777 AS TO IAS. THE PLT STATED HE HAD REDUCED TO 250 IAS ALTHOUGH NO SPD WAS ASSIGNED. THE CTLR TOLD THE B777 TO INCREASE TO +300 KTS AND HAD THE B737 REDUCE TO 280 KIAS. MORE ACFT ARE REDUCING SPD IN DSCNT PHASE OF FLT AND NOT ADVISING ATC.

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.