TCASII RA alert B757 crew at FL390 to crossing traffic beneath them. RA calls for climb which PIC does. ZOA controller states that aircraft Y, a T38, was at FL350.

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Attributes
ACN	362777
Time
Date	199703
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : oal
State Reference	NV
Altitude	msl bound lower : 39000 msl bound upper : 39600
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zoa
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	enroute other
Flight Plan	IFR
Aircraft 2
Operator	other
Make Model Name	Talon
Operating Under FAR Part	other : other
Flight Phase	cruise other
Route In Use	enroute other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time total : 16000 flight time type : 320
ASRS Report	362777
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
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 other flight crewa
Resolutory Action	flight crew : took evasive action flight crew : returned to intended course or assigned course
Consequence	Other
Miss Distance	horizontal : 0 vertical : 4000
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation other

Narrative:

While level at FL390 in smooth air, we received a TCASII TA followed almost immediately by a resolution command to climb. I disconnected the autoplt and began an immediate climb. The seat belt sign was turned on during the maneuver. TCASII showed a conflicting aircraft 500 ft directly below us. After we were clear of conflict, a small military aircraft (possibly a T38/F5) was sighted going away to our left, several thousand ft below us. The first officer said he had that aircraft insight approaching from our right just prior to the TCASII resolution. ZOA was notified. They said they had the military aircraft level at FL350. Our maximum altitude was FL396. I feel there may have been faulty transponder/TCASII communication which caused the resolution. At no time do I feel our aircraft or our passenger were in danger.

Original NASA ASRS Text

Title: TCASII RA ALERT B757 CREW AT FL390 TO XING TFC BENEATH THEM. RA CALLS FOR CLB WHICH PIC DOES. ZOA CTLR STATES THAT ACFT Y, A T38, WAS AT FL350.

Narrative: WHILE LEVEL AT FL390 IN SMOOTH AIR, WE RECEIVED A TCASII TA FOLLOWED ALMOST IMMEDIATELY BY A RESOLUTION COMMAND TO CLB. I DISCONNECTED THE AUTOPLT AND BEGAN AN IMMEDIATE CLB. THE SEAT BELT SIGN WAS TURNED ON DURING THE MANEUVER. TCASII SHOWED A CONFLICTING ACFT 500 FT DIRECTLY BELOW US. AFTER WE WERE CLR OF CONFLICT, A SMALL MIL ACFT (POSSIBLY A T38/F5) WAS SIGHTED GOING AWAY TO OUR L, SEVERAL THOUSAND FT BELOW US. THE FO SAID HE HAD THAT ACFT INSIGHT APCHING FROM OUR R JUST PRIOR TO THE TCASII RESOLUTION. ZOA WAS NOTIFIED. THEY SAID THEY HAD THE MIL ACFT LEVEL AT FL350. OUR MAX ALT WAS FL396. I FEEL THERE MAY HAVE BEEN FAULTY XPONDER/TCASII COM WHICH CAUSED THE RESOLUTION. AT NO TIME DO I FEEL OUR ACFT OR OUR PAX WERE IN DANGER.

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.