B737-300 crew and another company aircraft had a TCASII RA in P50 class B airspace.

Attributes
ACN	593590
Time
Date	200309
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : iwa.vortac
State Reference	AZ
Altitude	msl bound lower : 7000 msl bound upper : 8000
Environment
Flight Conditions	IMC
Weather Elements	Turbulence Thunderstorm Rain
Aircraft 1
Controlling Facilities	tracon : p50.tracon
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	climbout : intermediate altitude
Route In Use	departure : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : p50.tracon
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude climbout other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 14000 flight time type : 5000
ASRS Report	593590
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	conflict : airborne critical inflight encounter : weather
Independent Detector	aircraft equipment : tcas other controllera other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance controller : separated traffic flight crew : took evasive action
Supplementary
Problem Areas	Flight Crew Human Performance Weather ATC Human Performance
Primary Problem	Ambiguous

Narrative:

Flight abc, cleared from 6000 ft to 7000 ft MSL, while holding at the 5 DME fix on the 070 degree radial off the iwa VOR, received a TCASII alert and ATC controller instruction to climb immediately referencing jet traffic in same airspace climbing from 6000 ft to 8000 ft. Flight abc deviating for WX in the terminal area (class B airspace) was directed to hold at the iwa 070 degree radial, 5-20 DME fix, turns our (the crew's) choice. Needed to take action to avoid a midair situation with what we think was a company transport jet. Predicated on a TCASII warning and associated ATC command, emergency authority/authorized was applied by the crew of flight abc. Circumstances: 1) poor WX (IMC, thunderstorms). 2) high crew workload. 3) confusing holding clearance -- short reaction time. 4) lost separation (lateral/vertical) between 2 aircraft. 5) second duty period in greater than 11 hours.

Original NASA ASRS Text

Title: B737-300 CREW AND ANOTHER COMPANY ACFT HAD A TCASII RA IN P50 CLASS B AIRSPACE.

Narrative: FLT ABC, CLRED FROM 6000 FT TO 7000 FT MSL, WHILE HOLDING AT THE 5 DME FIX ON THE 070 DEG RADIAL OFF THE IWA VOR, RECEIVED A TCASII ALERT AND ATC CTLR INSTRUCTION TO CLB IMMEDIATELY REFING JET TFC IN SAME AIRSPACE CLBING FROM 6000 FT TO 8000 FT. FLT ABC DEVIATING FOR WX IN THE TERMINAL AREA (CLASS B AIRSPACE) WAS DIRECTED TO HOLD AT THE IWA 070 DEG RADIAL, 5-20 DME FIX, TURNS OUR (THE CREW'S) CHOICE. NEEDED TO TAKE ACTION TO AVOID A MIDAIR SIT WITH WHAT WE THINK WAS A COMPANY TRANSPORT JET. PREDICATED ON A TCASII WARNING AND ASSOCIATED ATC COMMAND, EMER AUTH WAS APPLIED BY THE CREW OF FLT ABC. CIRCUMSTANCES: 1) POOR WX (IMC, TSTMS). 2) HIGH CREW WORKLOAD. 3) CONFUSING HOLDING CLRNC -- SHORT REACTION TIME. 4) LOST SEPARATION (LATERAL/VERT) BTWN 2 ACFT. 5) SECOND DUTY PERIOD IN GREATER THAN 11 HRS.

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.