ARTCC radar controller descended a B727 through the altitude of an MD80 with less than standard separation. Controller was distraction by amending a flight plan and did not see the potential conflict until it was too late to maintain legal separation. Both aircraft were turned and the B727 told to expedite descent. TCASII gave an RA which the B727 ignored as they had the MD80 in sight.

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Attributes
ACN	368798
Time
Date	199705
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : elp
State Reference	TX
Altitude	msl bound lower : 30000 msl bound upper : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zab
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar pilot : private
Experience	controller non radar : 17 controller radar : 16 controller supervisory : 3 flight time total : 100
ASRS Report	368798
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 180 flight time total : 6000 flight time type : 3000
ASRS Report	368624
Events
Anomaly	conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	Other
Miss Distance	horizontal : 21000 vertical : 1000
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Aircraft #1 at FL330, approximately 60 mi northwest of elp, requested a lower altitude. I had been amending another flight plan and when aircraft #1 called with his request, I realized how close he was to his destination airport so I issued the descent. I then realized aircraft #2, an overflt at FL310, was traffic for aircraft #1. I issued 40 degree left turns to both aircraft and asked aircraft #1 to expedite through FL290 and to report leaving FL290. Separation was lost at XA14Z. The closest proximity was 4 mi and 1000 ft. Supplemental information from acn 368624: we could not query the controller about the other aircraft. Soon got an RA to climb followed by ARTCC control instruction to turn left 40 degrees in concurrence with the MD80 airline airplane to do the same. We disregarded the TCASII RA and complied with the controller's instruction. I estimate we passed behind the jet by about 1 mi.

Original NASA ASRS Text

Title: ARTCC RADAR CTLR DSNDED A B727 THROUGH THE ALT OF AN MD80 WITH LTSS. CTLR WAS DISTR BY AMENDING A FLT PLAN AND DID NOT SEE THE POTENTIAL CONFLICT UNTIL IT WAS TOO LATE TO MAINTAIN LEGAL SEPARATION. BOTH ACFT WERE TURNED AND THE B727 TOLD TO EXPEDITE DSCNT. TCASII GAVE AN RA WHICH THE B727 IGNORED AS THEY HAD THE MD80 IN SIGHT.

Narrative: ACFT #1 AT FL330, APPROX 60 MI NW OF ELP, REQUESTED A LOWER ALT. I HAD BEEN AMENDING ANOTHER FLT PLAN AND WHEN ACFT #1 CALLED WITH HIS REQUEST, I REALIZED HOW CLOSE HE WAS TO HIS DEST ARPT SO I ISSUED THE DSCNT. I THEN REALIZED ACFT #2, AN OVERFLT AT FL310, WAS TFC FOR ACFT #1. I ISSUED 40 DEG L TURNS TO BOTH ACFT AND ASKED ACFT #1 TO EXPEDITE THROUGH FL290 AND TO RPT LEAVING FL290. SEPARATION WAS LOST AT XA14Z. THE CLOSEST PROX WAS 4 MI AND 1000 FT. SUPPLEMENTAL INFO FROM ACN 368624: WE COULD NOT QUERY THE CTLR ABOUT THE OTHER ACFT. SOON GOT AN RA TO CLB FOLLOWED BY ARTCC CTL INSTRUCTION TO TURN L 40 DEGS IN CONCURRENCE WITH THE MD80 AIRLINE AIRPLANE TO DO THE SAME. WE DISREGARDED THE TCASII RA AND COMPLIED WITH THE CTLR'S INSTRUCTION. I ESTIMATE WE PASSED BEHIND THE JET BY ABOUT 1 MI.

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.