<< >> NASA ASRS Report 194324, November 1991

Possible less than standard separation between air carrier medium large transport and ukn traffic both being controled by slc TRACON.

Attributes
ACN	194324
Time
Date	199111
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ogd airport : slc
State Reference	UT
Altitude	msl bound lower : 12000 msl bound upper : 13000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : slc
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : atp
Experience	flight time last 90 days : 230 flight time total : 4000 flight time type : 300
ASRS Report	194324
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : clearance non adherence : published procedure
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

We were given a clearance to descend to 13000 ft and acknowledged. A few moments later, we were issued a clearance to 10000 ft and acknowledged. A few moments later traffic was called out climbing to 12000. We (cockpit crew) looked at each other and ensured we heard the traffic call correctly then asked ATC where the traffic was again. We were at 12000 ft. They replied we were told to maintain 13000 ft and gave us an avoidance vector and climb. We followed the instructions and climbed back to 13000 ft immediately. After landing, we called slc approach and were told our prompt compliance with the avoidance vector and climb had kept a traffic conflict from developing and no further action was necessary. (No alarms had gone off).

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Original NASA ASRS Text

Title: POSSIBLE LTSS BTWN ACR MLG AND UKN TFC BOTH BEING CTLED BY SLC TRACON.

Narrative: WE WERE GIVEN A CLRNC TO DSND TO 13000 FT AND ACKNOWLEDGED. A FEW MOMENTS LATER, WE WERE ISSUED A CLRNC TO 10000 FT AND ACKNOWLEDGED. A FEW MOMENTS LATER TFC WAS CALLED OUT CLBING TO 12000. WE (COCKPIT CREW) LOOKED AT EACH OTHER AND ENSURED WE HEARD THE TFC CALL CORRECTLY THEN ASKED ATC WHERE THE TFC WAS AGAIN. WE WERE AT 12000 FT. THEY REPLIED WE WERE TOLD TO MAINTAIN 13000 FT AND GAVE US AN AVOIDANCE VECTOR AND CLB. WE FOLLOWED THE INSTRUCTIONS AND CLBED BACK TO 13000 FT IMMEDIATELY. AFTER LNDG, WE CALLED SLC APCH AND WERE TOLD OUR PROMPT COMPLIANCE WITH THE AVOIDANCE VECTOR AND CLB HAD KEPT A TFC CONFLICT FROM DEVELOPING AND NO FURTHER ACTION WAS NECESSARY. (NO ALARMS HAD GONE OFF).

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.