Flight crew of an large transport descended below assigned altitude in response to a TCASII RA.

Attributes
ACN	317800
Time
Date	199510
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : ctw
State Reference	OH
Altitude	msl bound lower : 26000 msl bound upper : 27000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other cruise other
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	other : unknown
Flight Phase	descent other
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	other other : other pilot : atp pilot : instrument pilot : cfi
Experience	flight time last 90 days : 200 flight time total : 33000 flight time type : 3000
ASRS Report	317800
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 24000 vertical : 1000
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were turned to a heading of 140 degrees magnetic by controller. Shortly after established on heading, TCASII called 'traffic' followed by descend, descend. Autoplt was disconnected and descent commenced. Traffic was shown on TCASII display at 12 O'clock, 4 1/2 mi descending 1000 ft above us. Captain obtained traffic visually and a turn to right commenced to assure clearance. ATC was advised of 'RA.' aircraft leveled at FL260. ATC responded traffic was not a factor and no conflict resulted. ATC said he was going to point out traffic, but high volume precluded doing so. ATC cleared us to descend and maintenance FL260.

Original NASA ASRS Text

Title: FLC OF AN LGT DSNDED BELOW ASSIGNED ALT IN RESPONSE TO A TCASII RA.

Narrative: WE WERE TURNED TO A HDG OF 140 DEGS MAGNETIC BY CTLR. SHORTLY AFTER ESTABLISHED ON HDG, TCASII CALLED 'TFC' FOLLOWED BY DSND, DSND. AUTOPLT WAS DISCONNECTED AND DSCNT COMMENCED. TFC WAS SHOWN ON TCASII DISPLAY AT 12 O'CLOCK, 4 1/2 MI DSNDING 1000 FT ABOVE US. CAPT OBTAINED TFC VISUALLY AND A TURN TO R COMMENCED TO ASSURE CLRNC. ATC WAS ADVISED OF 'RA.' ACFT LEVELED AT FL260. ATC RESPONDED TFC WAS NOT A FACTOR AND NO CONFLICT RESULTED. ATC SAID HE WAS GOING TO POINT OUT TFC, BUT HIGH VOLUME PRECLUDED DOING SO. ATC CLRED US TO DSND AND MAINT FL260.

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.