TCASII RA prevents a potential conflict from getting to be any more than that.

Attributes
ACN	221510
Time
Date	199209
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : crw
State Reference	WV
Altitude	msl bound lower : 4500 msl bound upper : 5500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : crw
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	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
Route In Use	enroute : direct
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 200 flight time total : 7000 flight time type : 3500
ASRS Report	221510
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 250 flight time total : 10000 flight time type : 1200
ASRS Report	221506
Events
Anomaly	conflict : airborne less severe non adherence : far other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 3000 vertical : 0
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

The flight was being controled by crw approach. Approach requested a reduction to final approach speed and a descent to 3000 ft. A few seconds later, they (approach) gave a turn to 250 degrees and said to resume normal speed. The aircraft had slats with 15 degrees flaps in order to configure for the approach and reduce the airspeed per ATC's request. The aircraft was descending at 2000 FPM (at 5500 MSL) when TCASII gave a TA and rapidly changed to an RA. TCASII called 'climb, climb' and the vsi showed green command lights requiring a climb of 1500 FPM or greater. Due to the confign of the aircraft (i.e., slats and flaps 15 degrees, 2000 FPM descent, and unspooled engines), the aircraft continued to descend to 4500 ft MSL. It took maximum power and the captain's assistance to the first officer in order to arrest the descent and begin climbing. ATC said that we turned into the VFR aircraft, even though they gave a turn from 210 degrees to 250 degrees. There was no mention (from ATC) about the VFR aircraft until after the evasive action was performed. Both pilots had 250 degrees on their heading bugs and 3000 ft. The climb command was cancelled at about 5000 ft. ATC gave a left turn to 190 degrees at which time the airport was sighted and a visual approach clearance was issued. Supplemental information from acn 221506: my last scan of the TCASII unit showed 0 ft vertical separation at 4500 ft. ATC made calls, however, we were unable to respond as we had no free hands. Once in the clear, I advised ATC what happened. He said he was 'aware of traffic' but he pointed traffic out to us. He also said 'we turned into traffic,' all the while we were on a 250 degree assigned heading. Visual contact with intruding aircraft was never made. A brief passenger announcement was made to alleviate any concerns due to the abruptness of the maneuvers. During deplaning most passenger appeared relieved and thankful that air carrier utilizes TCASII equipment. This captain is also thankful.

Original NASA ASRS Text

Title: TCASII RA PREVENTS A POTENTIAL CONFLICT FROM GETTING TO BE ANY MORE THAN THAT.

Narrative: THE FLT WAS BEING CTLED BY CRW APCH. APCH REQUESTED A REDUCTION TO FINAL APCH SPD AND A DSCNT TO 3000 FT. A FEW SECONDS LATER, THEY (APCH) GAVE A TURN TO 250 DEGS AND SAID TO RESUME NORMAL SPD. THE ACFT HAD SLATS WITH 15 DEGS FLAPS IN ORDER TO CONFIGURE FOR THE APCH AND REDUCE THE AIRSPD PER ATC'S REQUEST. THE ACFT WAS DSNDING AT 2000 FPM (AT 5500 MSL) WHEN TCASII GAVE A TA AND RAPIDLY CHANGED TO AN RA. TCASII CALLED 'CLB, CLB' AND THE VSI SHOWED GREEN COMMAND LIGHTS REQUIRING A CLB OF 1500 FPM OR GREATER. DUE TO THE CONFIGN OF THE ACFT (I.E., SLATS AND FLAPS 15 DEGS, 2000 FPM DSCNT, AND UNSPOOLED ENGS), THE ACFT CONTINUED TO DSND TO 4500 FT MSL. IT TOOK MAX PWR AND THE CAPT'S ASSISTANCE TO THE FO IN ORDER TO ARREST THE DSCNT AND BEGIN CLBING. ATC SAID THAT WE TURNED INTO THE VFR ACFT, EVEN THOUGH THEY GAVE A TURN FROM 210 DEGS TO 250 DEGS. THERE WAS NO MENTION (FROM ATC) ABOUT THE VFR ACFT UNTIL AFTER THE EVASIVE ACTION WAS PERFORMED. BOTH PLTS HAD 250 DEGS ON THEIR HDG BUGS AND 3000 FT. THE CLB COMMAND WAS CANCELLED AT ABOUT 5000 FT. ATC GAVE A L TURN TO 190 DEGS AT WHICH TIME THE ARPT WAS SIGHTED AND A VISUAL APCH CLRNC WAS ISSUED. SUPPLEMENTAL INFO FROM ACN 221506: MY LAST SCAN OF THE TCASII UNIT SHOWED 0 FT VERT SEPARATION AT 4500 FT. ATC MADE CALLS, HOWEVER, WE WERE UNABLE TO RESPOND AS WE HAD NO FREE HANDS. ONCE IN THE CLR, I ADVISED ATC WHAT HAPPENED. HE SAID HE WAS 'AWARE OF TFC' BUT HE POINTED TFC OUT TO US. HE ALSO SAID 'WE TURNED INTO TFC,' ALL THE WHILE WE WERE ON A 250 DEG ASSIGNED HDG. VISUAL CONTACT WITH INTRUDING ACFT WAS NEVER MADE. A BRIEF PAX ANNOUNCEMENT WAS MADE TO ALLEVIATE ANY CONCERNS DUE TO THE ABRUPTNESS OF THE MANEUVERS. DURING DEPLANING MOST PAX APPEARED RELIEVED AND THANKFUL THAT ACR UTILIZES TCASII EQUIP. THIS CAPT IS ALSO THANKFUL.

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.