Altitude deviation altitude excursion during response to TCASII RA. False warning.

Attributes
ACN	217329
Time
Date	199208
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : iiu
State Reference	KY
Altitude	msl bound lower : 24400 msl bound upper : 25000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 8400 flight time type : 3500
ASRS Report	217329
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : flight engineer pilot : commercial pilot : atp
ASRS Report	217344
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 : returned to intended course or assigned course
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 6000 vertical : 1000
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Cruise altitude of 25000 ft, heading sbound 106 DME south of iiu VOR received TCASII TA followed by TCASII RA to descend at least 2000-4000 FPM. Upon reaching 24400 ft aircraft approaching became visual contact. Descent was stopped and ATC was advised. ATC reissued climb back to 25000 ft. ATC said there was no conflict and separation with other traffic was not compromised. All procedures were followed per FAA requirements involving TCASII operations. Problem was most likely created by possible faulty TCASII. TCASII was written up in aircraft logbook for maintenance inspection.

Original NASA ASRS Text

Title: ALTDEV ALT EXCURSION DURING RESPONSE TO TCASII RA. FALSE WARNING.

Narrative: CRUISE ALT OF 25000 FT, HDG SBOUND 106 DME S OF IIU VOR RECEIVED TCASII TA FOLLOWED BY TCASII RA TO DSND AT LEAST 2000-4000 FPM. UPON REACHING 24400 FT ACFT APCHING BECAME VISUAL CONTACT. DSCNT WAS STOPPED AND ATC WAS ADVISED. ATC REISSUED CLB BACK TO 25000 FT. ATC SAID THERE WAS NO CONFLICT AND SEPARATION WITH OTHER TFC WAS NOT COMPROMISED. ALL PROCS WERE FOLLOWED PER FAA REQUIREMENTS INVOLVING TCASII OPS. PROBLEM WAS MOST LIKELY CREATED BY POSSIBLE FAULTY TCASII. TCASII WAS WRITTEN UP IN ACFT LOGBOOK FOR MAINT INSPECTION.

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.