An air carrier medium large transport descended in response to a TCASII command.

Attributes
ACN	239300
Time
Date	199304
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : bwi
State Reference	MD
Altitude	msl bound lower : 8700 msl bound upper : 10000
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	cruise other descent other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : commercial pilot : flight engineer pilot : instrument
Experience	flight time last 90 days : 200 flight time total : 10000 flight time type : 4500
ASRS Report	239300
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	controller : issued new clearance flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 6000 vertical : 300
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Being vectored for approach to runway 33L at bwi. Level at assigned altitude 10000 ft MSL. Approach control (bwi on frequency 119.4) assigned heading 220 degrees, then assigned heading 290 degrees. While in the right turn to 290 degrees, TCASII issued TA, followed by RA that called for descent followed by increased descent. We followed TCASII commands which ceased at 8700 ft MSL. I then advised bwi approach that we responded to an 'RA,' and were level at 8700 ft MSL. We were then cleared to descend and maintain 4000 ft MSL. TCASII performed correctly. Visually spotted the conflicting traffic as we were leveling at 8700 ft MSL. There was heavy traffic at the time and the approach controller became overloaded.

Original NASA ASRS Text

Title: AN ACR MLG DSNDED IN RESPONSE TO A TCASII COMMAND.

Narrative: BEING VECTORED FOR APCH TO RWY 33L AT BWI. LEVEL AT ASSIGNED ALT 10000 FT MSL. APCH CTL (BWI ON FREQ 119.4) ASSIGNED HDG 220 DEGS, THEN ASSIGNED HDG 290 DEGS. WHILE IN THE R TURN TO 290 DEGS, TCASII ISSUED TA, FOLLOWED BY RA THAT CALLED FOR DSCNT FOLLOWED BY INCREASED DSCNT. WE FOLLOWED TCASII COMMANDS WHICH CEASED AT 8700 FT MSL. I THEN ADVISED BWI APCH THAT WE RESPONDED TO AN 'RA,' AND WERE LEVEL AT 8700 FT MSL. WE WERE THEN CLRED TO DSND AND MAINTAIN 4000 FT MSL. TCASII PERFORMED CORRECTLY. VISUALLY SPOTTED THE CONFLICTING TFC AS WE WERE LEVELING AT 8700 FT MSL. THERE WAS HVY TFC AT THE TIME AND THE APCH CTLR BECAME OVERLOADED.

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.