False warning. Air carrier crew receives a TCASII RA that later proves to be incorrect.

Attributes
ACN	299152
Time
Date	199503
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : mem
State Reference	TN
Altitude	msl bound lower : 7000 msl bound upper : 7000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : mem
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
ASRS Report	299152
Person 2
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : flight engineer pilot : instrument pilot : commercial
ASRS Report	298933
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : took evasive action
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

In RA/TA mode, TCASII showed traffic at our altitude (level 7000 ft) then target immediately changed altitude to 2000 ft below us. Then target showed 200 ft below us and TCASII gave RA to 'climb, now,' which we complied with (readout was erratic for target). Told ATC that we were going back down to assigned altitude 7000 ft. ATC then confirmed traffic was at 5000 ft. TCASII was written up on the ground.

Original NASA ASRS Text

Title: FALSE WARNING. ACR CREW RECEIVES A TCASII RA THAT LATER PROVES TO BE INCORRECT.

Narrative: IN RA/TA MODE, TCASII SHOWED TFC AT OUR ALT (LEVEL 7000 FT) THEN TARGET IMMEDIATELY CHANGED ALT TO 2000 FT BELOW US. THEN TARGET SHOWED 200 FT BELOW US AND TCASII GAVE RA TO 'CLB, NOW,' WHICH WE COMPLIED WITH (READOUT WAS ERRATIC FOR TARGET). TOLD ATC THAT WE WERE GOING BACK DOWN TO ASSIGNED ALT 7000 FT. ATC THEN CONFIRMED TFC WAS AT 5000 FT. TCASII WAS WRITTEN UP ON THE GND.

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.