Medium large transport descends 600 ft in response to a TCASII RA.

Attributes
ACN	257369
Time
Date	199311
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : clt
State Reference	NC
Altitude	msl bound lower : 11400 msl bound upper : 12000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : ztl
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	arrival other arrival star : star
Flight Plan	IFR
Aircraft 2
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Flight Phase	cruise other
Flight Plan	VFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : commercial pilot : instrument
Experience	flight time last 90 days : 180 flight time total : 9000 flight time type : 4200
ASRS Report	257369
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	Other
Miss Distance	horizontal : 4000 vertical : 1000
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

While descending into clt on the shine 5 arrival, ZTL called out VFR traffic at 10 O'clock/20 mi 12500 ft unconfirmed. We noted traffic on TCASII at about 1130 O'clock position. Later, the TCASII showed traffic (different target) at 10 mi or less and 400 ft above our altitude. The captain then told center that we were turning off course to the right to avoid the traffic. As he was speaking to center, we got a TA followed almost immediately by a 'descend' RA calling for a 1500 FPM rate of descent. I disconnected the autoplt and autothrottles and followed the TCASII instructions to an altitude of 11400 ft. The aircraft (which we saw visually after we had started descending) passed less that 1 mi in front and 1000 ft above us. I believe the light transport was level at 12500 ft, however, our TCASII display showed only 400 ft above us, so that is why we got an RA.

Original NASA ASRS Text

Title: MLG DSNDS 600 FT IN RESPONSE TO A TCASII RA.

Narrative: WHILE DSNDING INTO CLT ON THE SHINE 5 ARR, ZTL CALLED OUT VFR TFC AT 10 O'CLOCK/20 MI 12500 FT UNCONFIRMED. WE NOTED TFC ON TCASII AT ABOUT 1130 O'CLOCK POS. LATER, THE TCASII SHOWED TFC (DIFFERENT TARGET) AT 10 MI OR LESS AND 400 FT ABOVE OUR ALT. THE CAPT THEN TOLD CTR THAT WE WERE TURNING OFF COURSE TO THE R TO AVOID THE TFC. AS HE WAS SPEAKING TO CTR, WE GOT A TA FOLLOWED ALMOST IMMEDIATELY BY A 'DSND' RA CALLING FOR A 1500 FPM RATE OF DSCNT. I DISCONNECTED THE AUTOPLT AND AUTOTHROTTLES AND FOLLOWED THE TCASII INSTRUCTIONS TO AN ALT OF 11400 FT. THE ACFT (WHICH WE SAW VISUALLY AFTER WE HAD STARTED DSNDING) PASSED LESS THAT 1 MI IN FRONT AND 1000 FT ABOVE US. I BELIEVE THE LTT WAS LEVEL AT 12500 FT, HOWEVER, OUR TCASII DISPLAY SHOWED ONLY 400 FT ABOVE US, SO THAT IS WHY WE GOT AN RA.

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.