Altitude deviation altitude excursion after TCASII RA received.

Attributes
ACN	223831
Time
Date	199210
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : den
State Reference	CO
Altitude	msl bound lower : 23000 msl bound upper : 24000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 75 flight time total : 6000 flight time type : 1000
ASRS Report	223831
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument pilot : flight engineer
Experience	flight time last 90 days : 160 flight time total : 5000 flight time type : 1050
ASRS Report	223828
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	controller : issued new clearance flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation other

Narrative:

Level FL240 radar vectors heading 360 degrees speed 250 KTS, received TCASII RA to 'monitor vertical speed,' followed by 'descend crossing descend.' I descended to FL230 while advising ATC. TCASII display had shown the conflicting traffic level at my altitude (FL240) and co-located at my position. ATC advised they had no traffic closer than 7 mi from us. ATC then gave us a heading of direct to kioa VOR and descend to FL220. I suspect our TCASII was displaying its own transponder. Maintenance was advised. I discussed the event with area manager at ZDV by telephone after landing.

Original NASA ASRS Text

Title: ALTDEV ALT EXCURSION AFTER TCASII RA RECEIVED.

Narrative: LEVEL FL240 RADAR VECTORS HDG 360 DEGS SPD 250 KTS, RECEIVED TCASII RA TO 'MONITOR VERT SPD,' FOLLOWED BY 'DSND XING DSND.' I DSNDED TO FL230 WHILE ADVISING ATC. TCASII DISPLAY HAD SHOWN THE CONFLICTING TFC LEVEL AT MY ALT (FL240) AND CO-LOCATED AT MY POS. ATC ADVISED THEY HAD NO TFC CLOSER THAN 7 MI FROM US. ATC THEN GAVE US A HDG OF DIRECT TO KIOA VOR AND DSND TO FL220. I SUSPECT OUR TCASII WAS DISPLAYING ITS OWN TRANSPONDER. MAINT WAS ADVISED. I DISCUSSED THE EVENT WITH AREA MGR AT ZDV BY TELEPHONE AFTER LNDG.

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.