ZAB controller described incident when incorrect read back was missed; aircraft given to another con...

Attributes
ACN	736857
Time
Date	200704
Place
Locale Reference	navaid : peq.vor
State Reference	TX
Altitude	msl single value : 36000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zab.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zab.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller military : 5.5 controller radar : 3.5
ASRS Report	736857
Events
Anomaly	conflict : airborne less severe other anomaly other
Independent Detector	atc equipment : conflict alert other controllera
Resolutory Action	controller : issued alert controller : issued new clearance
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance

Narrative:

Aircraft #1 was issued a pilot's discretion descent to FL360 and handed off to the high sector. After reviewing traffic; aircraft #1 was told to amend altitude; descend now; maintain FL360. The aircraft read back FL260. The aircraft was then shipped to the next sector where there was traffic (aircraft #2) at FL350. I believe part of the contributing factor is the radios on the sector. They are constantly being turned on for performance issues and only being reset instead of replaced. The pilot's transmission was full of static. Secondly; in my understanding of the 7110.65; when I need to remove a pilot's discretion descent; I need to state 'amend altitude' which I feel the pilot is assuming a new number; not removal of discretion. As far as human factors; the clearance was issued twice to the aircraft; once as pilot's discretion which was read back correctly; then the repeat of pilot's discretion; which was not read back correctly; causing some complacency. Also; prior to this aircraft; the same clearance was given to another aircraft in the same order with the same altitudes; also landing elp. So it had been the fourth time in a row to hear the same readback.

Original NASA ASRS Text

Title: ZAB CTLR DESCRIBED INCIDENT WHEN INCORRECT READ BACK WAS MISSED; ACFT GIVEN TO ANOTHER CTLR; AND POTENTIAL CONFLICT DEVELOPED.

Narrative: ACFT #1 WAS ISSUED A PLT'S DISCRETION DSCNT TO FL360 AND HANDED OFF TO THE HIGH SECTOR. AFTER REVIEWING TFC; ACFT #1 WAS TOLD TO AMEND ALT; DSND NOW; MAINTAIN FL360. THE ACFT READ BACK FL260. THE ACFT WAS THEN SHIPPED TO THE NEXT SECTOR WHERE THERE WAS TFC (ACFT #2) AT FL350. I BELIEVE PART OF THE CONTRIBUTING FACTOR IS THE RADIOS ON THE SECTOR. THEY ARE CONSTANTLY BEING TURNED ON FOR PERFORMANCE ISSUES AND ONLY BEING RESET INSTEAD OF REPLACED. THE PLT'S XMISSION WAS FULL OF STATIC. SECONDLY; IN MY UNDERSTANDING OF THE 7110.65; WHEN I NEED TO REMOVE A PLT'S DISCRETION DSCNT; I NEED TO STATE 'AMEND ALT' WHICH I FEEL THE PLT IS ASSUMING A NEW NUMBER; NOT REMOVAL OF DISCRETION. AS FAR AS HUMAN FACTORS; THE CLRNC WAS ISSUED TWICE TO THE ACFT; ONCE AS PLT'S DISCRETION WHICH WAS READ BACK CORRECTLY; THEN THE REPEAT OF PLT'S DISCRETION; WHICH WAS NOT READ BACK CORRECTLY; CAUSING SOME COMPLACENCY. ALSO; PRIOR TO THIS ACFT; THE SAME CLRNC WAS GIVEN TO ANOTHER ACFT IN THE SAME ORDER WITH THE SAME ALTS; ALSO LNDG ELP. SO IT HAD BEEN THE FOURTH TIME IN A ROW TO HEAR THE SAME READBACK.

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.

ZAB controller described incident when incorrect read back was missed; aircraft given to another controller; and potential conflict developed.