<< >> NASA ASRS Report 688667, February 2006

ZLA controller experienced operational error at FL240 when issuing incorrect descent clearance and then not having time to correct the error.

Attributes
ACN	688667
Time
Date	200602
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : hec.vortac
State Reference	CA
Altitude	msl single value : 24000
Environment
Weather Elements	Ice Rain
Light	Night
Aircraft 1
Controlling Facilities	artcc : zla.artcc
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	arrival star : n/s
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zla.artcc
Operator	common carrier : air carrier
Make Model Name	Brasilia EMB-120 All Series
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	arrival star : n/s
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Experience	controller radar : 19
ASRS Report	688667
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : developmental
Experience	controller limited radar : 6 controller military : 5 controller radar : 2 controller supervisory : 2
ASRS Report	688806
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation
Independent Detector	aircraft equipment : tcas other controllera other controllerb
Resolutory Action	controller : issued alert controller : issued new clearance flight crew : took evasive action
Consequence	faa : investigated
Miss Distance	horizontal : 21000 vertical : 0
Supplementary
Problem Areas	ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Lax was east confign. Rain and icing along arrival rtes. Air carrier Y (E120) checked in level at FL220 landing lax. Propellers normally are routed over pmd; but lax being east traffic; preferential routing is south route into socal approach airspace. 6 mins later; air carrier X checks in level at FL240. They land ont airport. 3 mins later; I issue air carrier X the standard dawna crossing restr of 12000 ft MSL. Being busy; I went back to my other situations. Less than 1 min after issuing the crossing restr; I realized my error and called air carrier X to stop their descent and maintain FL230. They had just vacated FL240. No response from air carrier X. Immediately called air carrier X again to stop their descent and maintain FL230. No response. Third call; tried to have air carrier X maintain FL230 and turn to heading 260 degrees to miss air carrier Y. Pilot finally answers; but it is too late.

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Original NASA ASRS Text

Title: ZLA CTLR EXPERIENCED OPERROR AT FL240 WHEN ISSUING INCORRECT DSCNT CLRNC AND THEN NOT HAVING TIME TO CORRECT THE ERROR.

Narrative: LAX WAS E CONFIGN. RAIN AND ICING ALONG ARR RTES. ACR Y (E120) CHKED IN LEVEL AT FL220 LNDG LAX. PROPS NORMALLY ARE ROUTED OVER PMD; BUT LAX BEING E TFC; PREFERENTIAL ROUTING IS S RTE INTO SOCAL APCH AIRSPACE. 6 MINS LATER; ACR X CHKS IN LEVEL AT FL240. THEY LAND ONT ARPT. 3 MINS LATER; I ISSUE ACR X THE STANDARD DAWNA XING RESTR OF 12000 FT MSL. BEING BUSY; I WENT BACK TO MY OTHER SITUATIONS. LESS THAN 1 MIN AFTER ISSUING THE XING RESTR; I REALIZED MY ERROR AND CALLED ACR X TO STOP THEIR DSCNT AND MAINTAIN FL230. THEY HAD JUST VACATED FL240. NO RESPONSE FROM ACR X. IMMEDIATELY CALLED ACR X AGAIN TO STOP THEIR DSCNT AND MAINTAIN FL230. NO RESPONSE. THIRD CALL; TRIED TO HAVE ACR X MAINTAIN FL230 AND TURN TO HDG 260 DEGS TO MISS ACR Y. PLT FINALLY ANSWERS; BUT IT IS TOO LATE.

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.