Medium large transport gets TCASII RA, ATC says no one in area. Mlt later determined to have faulty ...

Attributes
ACN	322340
Time
Date	199512
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : hvq
State Reference	WV
Altitude	msl bound lower : 30700 msl bound upper : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid
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 : direct
Flight Plan	IFR
Aircraft 2
Operator	other
Make Model Name	Military Transport
Operating Under FAR Part	other : other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 210 flight time total : 6000
ASRS Report	322340
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

During cruise at FL310 directly over hvq, we received an RA at the 10 O'clock position 5 NM +300 ft. We tried to acquire visually with no luck. We were looking directly into the sun. 10 seconds later we were to 'descend, descend.' the first officer (his leg) began a descent as I advised ATC. The target got within 2.0 NM and moved to 10 O'clock position and +600 ft. ATC told us he had nobody in that position. After about 45 seconds the RA was gone and we returned to FL310. We had descended about 300 ft maximum. After further discussion, it was determined that a military C9 at FL370 had a faulty mode C. After this the flight proceeded normally.

Original NASA ASRS Text

Title: MLG GETS TCASII RA, ATC SAYS NO ONE IN AREA. MLT LATER DETERMINED TO HAVE FAULTY MODE C.

Narrative: DURING CRUISE AT FL310 DIRECTLY OVER HVQ, WE RECEIVED AN RA AT THE 10 O'CLOCK POS 5 NM +300 FT. WE TRIED TO ACQUIRE VISUALLY WITH NO LUCK. WE WERE LOOKING DIRECTLY INTO THE SUN. 10 SECONDS LATER WE WERE TO 'DSND, DSND.' THE FO (HIS LEG) BEGAN A DSCNT AS I ADVISED ATC. THE TARGET GOT WITHIN 2.0 NM AND MOVED TO 10 O'CLOCK POS AND +600 FT. ATC TOLD US HE HAD NOBODY IN THAT POS. AFTER ABOUT 45 SECONDS THE RA WAS GONE AND WE RETURNED TO FL310. WE HAD DSNDED ABOUT 300 FT MAX. AFTER FURTHER DISCUSSION, IT WAS DETERMINED THAT A MIL C9 AT FL370 HAD A FAULTY MODE C. AFTER THIS THE FLT PROCEEDED NORMALLY.

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.

Medium large transport gets TCASII RA, ATC says no one in area. Mlt later determined to have faulty mode C.