Air carrier receives TCASII RA, responds.

Attributes
ACN	191544
Time
Date	199110
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bwi
State Reference	MD
Altitude	msl bound lower : 2000 msl bound upper : 2900
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bwi
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent : approach
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 210 flight time total : 9000 flight time type : 3000
ASRS Report	191544
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 6000 vertical : 900
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

At 2500 ft approach told us of light aircraft traffic 10 O'clock 3 mi. We were told to descend to 2000. When this was started TCASII system immediately went from TA to RA. We followed its cue and climbed to 2900 ft. Controller said it was not necessary for us to do that, but we never saw the aircraft. I thought the TCASII worked properly.

Original NASA ASRS Text

Title: ACR RECEIVES TCASII RA, RESPONDS.

Narrative: AT 2500 FT APCH TOLD US OF LIGHT ACFT TFC 10 O'CLOCK 3 MI. WE WERE TOLD TO DSND TO 2000. WHEN THIS WAS STARTED TCASII SYS IMMEDIATELY WENT FROM TA TO RA. WE FOLLOWED ITS CUE AND CLBED TO 2900 FT. CTLR SAID IT WAS NOT NECESSARY FOR US TO DO THAT, BUT WE NEVER SAW THE ACFT. I THOUGHT THE TCASII WORKED PROPERLY.

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.