Flight crew of a B757 given clearance to descend from FL390 to FL370 to avoid WX resulted in a TCASII RA and leveling off at FL380 to avoid traffic at FL370.

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Attributes
ACN	486620
Time
Date	200009
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : dsm.vortac
State Reference	IA
Altitude	msl bound lower : 38000 msl bound upper : 39000
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zmp.artcc
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zmp.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 125
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	486620
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : multi engine pilot : instrument
Events
Anomaly	conflict : airborne less severe inflight encounter : weather non adherence : required legal separation
Independent Detector	aircraft equipment : tcas
Resolutory Action	controller : separated traffic flight crew : took precautionary avoidance action
Miss Distance	vertical : 1000
Supplementary
Problem Areas	Flight Crew Human Performance Weather ATC Human Performance
Primary Problem	Weather
Air Traffic Incident	Operational Error

Narrative:

In VMC between 2 WX cells at FL390. Given a clearance to turn left 30 degrees for traffic. Unable to comply due to WX. Then given clearance to expedite descent to FL370. On descent, got RA for traffic at 1 O'clock position at FL370. Complied with RA and leveled at FL380. Reported RA to ATC. We also had visual on traffic at FL370. Once clear of traffic, given clearance to climb back to FL390.

Original NASA ASRS Text

Title: FLC OF A B757 GIVEN CLRNC TO DSND FROM FL390 TO FL370 TO AVOID WX RESULTED IN A TCASII RA AND LEVELING OFF AT FL380 TO AVOID TFC AT FL370.

Narrative: IN VMC BTWN 2 WX CELLS AT FL390. GIVEN A CLRNC TO TURN L 30 DEGS FOR TFC. UNABLE TO COMPLY DUE TO WX. THEN GIVEN CLRNC TO EXPEDITE DSCNT TO FL370. ON DSCNT, GOT RA FOR TFC AT 1 O'CLOCK POS AT FL370. COMPLIED WITH RA AND LEVELED AT FL380. RPTED RA TO ATC. WE ALSO HAD VISUAL ON TFC AT FL370. ONCE CLR OF TFC, GIVEN CLRNC TO CLB BACK TO FL390.

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.