Medium large transport has TCASII RA. Descends below assigned on return to altitude.

Attributes
ACN	276504
Time
Date	199407
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bwi
State Reference	MD
Altitude	msl bound lower : 1700 msl bound upper : 3300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bwi
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude cruise other descent other
Route In Use	approach : straight in
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 215 flight time total : 9500
ASRS Report	276504
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : atp pilot : instrument
Events
Anomaly	altitude deviation : overshoot altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

At 2000 ft 12 DME from bwi on base leg for localizer 10, we received a TA then RA on TCASII to climb. Other aircraft at 1800-1900 ft at 6 O'clock. We climbed to 3300 ft then descended back to 2000 ft. I had disconnected the autoplt during the RA and thought it was still connected and realized as we passed 2000 ft for 1700 ft it was off. Controller said check altitude. We responded and returned to 2000 ft.

Original NASA ASRS Text

Title: MLG HAS TCASII RA. DSNDS BELOW ASSIGNED ON RETURN TO ALT.

Narrative: AT 2000 FT 12 DME FROM BWI ON BASE LEG FOR LOC 10, WE RECEIVED A TA THEN RA ON TCASII TO CLB. OTHER ACFT AT 1800-1900 FT AT 6 O'CLOCK. WE CLBED TO 3300 FT THEN DSNDED BACK TO 2000 FT. I HAD DISCONNECTED THE AUTOPLT DURING THE RA AND THOUGHT IT WAS STILL CONNECTED AND REALIZED AS WE PASSED 2000 FT FOR 1700 FT IT WAS OFF. CTLR SAID CHK ALT. WE RESPONDED AND RETURNED TO 2000 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.