TCASII RA creates loss of separation potential conflict less than standard separation.

Attributes
ACN	177940
Time
Date	199105
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bwi
State Reference	MD
Altitude	msl bound lower : 3700 msl bound upper : 4000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : bwi artcc : zfw
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	descent other
Route In Use	approach : visual
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 : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 8200 flight time type : 1000
ASRS Report	177949
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : undershoot altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance non adherence : required legal separation
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 9000 vertical : 300
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

Cleared for visibility approach to runway 33L and descending out of 4000' approach control advised to increase rate of descent out of 4000 through 3000'. RA on TCAS went off and directed us to climb 1500-2000 FPM, which is what we did. We leveled off at 4000' and the RA went away and all clear was called.

Original NASA ASRS Text

Title: TCASII RA CREATES LOSS OF SEPARATION POTENTIAL CONFLICT LESS THAN STANDARD SEPARATION.

Narrative: CLRED FOR VIS APCH TO RWY 33L AND DSNDING OUT OF 4000' APCH CTL ADVISED TO INCREASE RATE OF DSNT OUT OF 4000 THROUGH 3000'. RA ON TCAS WENT OFF AND DIRECTED US TO CLB 1500-2000 FPM, WHICH IS WHAT WE DID. WE LEVELED OFF AT 4000' AND THE RA WENT AWAY AND ALL CLR WAS CALLED.

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.