B737-800 flight crew receives a TCASII TA while on an ATC assigned heading.

Attributes
ACN	582419
Time
Date	200305
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	intersection : lidat
State Reference	NV
Altitude	msl single value : 28000
Environment
Flight Conditions	Mixed
Weather Elements	Thunderstorm
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zoa.artcc
Operator	common carrier : air carrier
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : approach descent : intermediate altitude
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 21000 flight time type : 5000
ASRS Report	582419
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	conflict : airborne less severe inflight encounter : weather non adherence : published procedure
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	none taken : anomaly accepted
Miss Distance	horizontal : 6080 vertical : 600
Supplementary
Problem Areas	Flight Crew Human Performance Weather ATC Facility ATC Human Performance
Primary Problem	ATC Human Performance

Narrative:

While on an assigned heading and on a descent per ATC clearance, we received a TA on the TCASII. The conflict was experienced with another aircraft that was climbing as we were descending. We did not deviate from our assigned ATC clearance. TCASII showed the traffic to be approximately 1 mi, and within 600 ft. There were thunderstorms in all quadrants.

Original NASA ASRS Text

Title: B737-800 FLT CREW RECEIVES A TCASII TA WHILE ON AN ATC ASSIGNED HDG.

Narrative: WHILE ON AN ASSIGNED HDG AND ON A DSCNT PER ATC CLRNC, WE RECEIVED A TA ON THE TCASII. THE CONFLICT WAS EXPERIENCED WITH ANOTHER ACFT THAT WAS CLBING AS WE WERE DSNDING. WE DID NOT DEVIATE FROM OUR ASSIGNED ATC CLRNC. TCASII SHOWED THE TFC TO BE APPROX 1 MI, AND WITHIN 600 FT. THERE WERE TSTMS IN ALL QUADRANTS.

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.