Air carrier flight crew responds to TCASII RA and, in so doing, climbs through assigned altitude.

Attributes
ACN	435371
Time
Date	199904
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : mdw.airport
State Reference	IL
Altitude	msl bound lower : 11500 msl bound upper : 14000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zau.artcc tracon : c90.tracon
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude
Route In Use	enroute other
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zau.artcc
Make Model Name	Twin Otter DHC-6
Operating Under FAR Part	Part 135
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude
Route In Use	enroute other
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 12000 flight time type : 200
ASRS Report	435371
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : atp pilot : cfi pilot : commercial pilot : multi engine
Experience	flight time last 90 days : 180 flight time total : 13000 flight time type : 1700
ASRS Report	436239
Events
Anomaly	conflict : nmac
Independent Detector	aircraft equipment : tcas
Resolutory Action	flight crew : took evasive action
Miss Distance	vertical : 400
Supplementary
Problem Areas	ATC Human Performance Flight Crew Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

We were given a clearance to climb and maintain 12000 ft by ord departure control. Between 11000 ft and 12000 ft, we were handed off to ZAU 120.12. Upon checking in with center, TCASII gave us a TA. The center informed us we were given this frequency in error and contact center on 127.07. At this same time TCASII gave us an RA and to climb at 6000 FPM. At this time TCASII showed other aircraft to be 400 ft below us. First officer complied with RA and I informed center we were cleared to 12000 ft but were climbing because of the RA. First officer and I both saw the other aircraft. It was a twin otter, out of about 14000 ft and was behind us. TCASII was still showing the other aircraft 400 ft below us. First officer leveled the airplane at 15000 ft. I informed center we were now level at 15000 ft. Then a clearance was issued to FL230. I estimate we missed the other aircraft by 400 ft.

Original NASA ASRS Text

Title: ACR FLC RESPONDS TO TCASII RA AND, IN SO DOING, CLBS THROUGH ASSIGNED ALT.

Narrative: WE WERE GIVEN A CLRNC TO CLB AND MAINTAIN 12000 FT BY ORD DEP CTL. BTWN 11000 FT AND 12000 FT, WE WERE HANDED OFF TO ZAU 120.12. UPON CHKING IN WITH CTR, TCASII GAVE US A TA. THE CTR INFORMED US WE WERE GIVEN THIS FREQ IN ERROR AND CONTACT CTR ON 127.07. AT THIS SAME TIME TCASII GAVE US AN RA AND TO CLB AT 6000 FPM. AT THIS TIME TCASII SHOWED OTHER ACFT TO BE 400 FT BELOW US. FO COMPLIED WITH RA AND I INFORMED CTR WE WERE CLRED TO 12000 FT BUT WERE CLBING BECAUSE OF THE RA. FO AND I BOTH SAW THE OTHER ACFT. IT WAS A TWIN OTTER, OUT OF ABOUT 14000 FT AND WAS BEHIND US. TCASII WAS STILL SHOWING THE OTHER ACFT 400 FT BELOW US. FO LEVELED THE AIRPLANE AT 15000 FT. I INFORMED CTR WE WERE NOW LEVEL AT 15000 FT. THEN A CLRNC WAS ISSUED TO FL230. I ESTIMATE WE MISSED THE OTHER ACFT BY 400 FT.

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.