TCASII false warning.

Attributes
ACN	297387
Time
Date	199502
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : mzb airport : san
State Reference	CA
Altitude	msl bound lower : 9600 msl bound upper : 11000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : owb
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Route In Use	enroute airway : san
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 200 flight time total : 14000 flight time type : 5000
ASRS Report	297387
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 300 flight time total : 18000 flight time type : 3000
ASRS Report	296948
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : anomaly accepted
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

During cruise in clear conditions over pacific ocean, TCASII TA received at about 12:30 O'clock relative then immediately switched to RA. First alert was at about 2 NM and plus 100 ft. RA initially indicated a descent rate of 2500 FPM. We complied with the 'RA' until clear of traffic which, after descent to 9600 ft appeared behind the aircraft at plus 1400 ft. Socal approach denied having any traffic within 5 NM of our position. We climbed back to initial altitude and the flight continued normally. At no time was the TCASII target visually sighted, although attempt was made. At no time was any TCASII malfunction indicated.

Original NASA ASRS Text

Title: TCASII FALSE WARNING.

Narrative: DURING CRUISE IN CLR CONDITIONS OVER PACIFIC OCEAN, TCASII TA RECEIVED AT ABOUT 12:30 O'CLOCK RELATIVE THEN IMMEDIATELY SWITCHED TO RA. FIRST ALERT WAS AT ABOUT 2 NM AND PLUS 100 FT. RA INITIALLY INDICATED A DSCNT RATE OF 2500 FPM. WE COMPLIED WITH THE 'RA' UNTIL CLR OF TFC WHICH, AFTER DSCNT TO 9600 FT APPEARED BEHIND THE ACFT AT PLUS 1400 FT. SOCAL APCH DENIED HAVING ANY TFC WITHIN 5 NM OF OUR POS. WE CLBED BACK TO INITIAL ALT AND THE FLT CONTINUED NORMALLY. AT NO TIME WAS THE TCASII TARGET VISUALLY SIGHTED, ALTHOUGH ATTEMPT WAS MADE. AT NO TIME WAS ANY TCASII MALFUNCTION INDICATED.

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.