TCASII TA RA climb evasive action taken from ghost target.

Attributes
ACN	200887
Time
Date	199202
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : zlc
State Reference	UT
Altitude	msl bound lower : 35000 msl bound upper : 35800
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zlc
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 12000 flight time type : 1200
ASRS Report	200887
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance 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:

Air carrier X received TCASII TA aurally and visually at 2 O'clock position on ehsi approximately 20 mi. ATC had not reported any traffic. We had no diamond targets on the ehsi in that position prior to the TA. Seconds later the TA became an RA, with the command 'climb, climb now'. We manually executed the climb from 35000 to approximately 35800 while captain asked ATC if he had any traffic for us. He reported none. The RA aural and visual ceased. Note: the TA became RA at approximately 10 mi at 2 O'clock. We returned to cruise FL350. Controller expressed no serious concern about our altitude deviation. He noted that he has had as many as 15 similar reports in the same area. Another pilot had just previously reported a similar event at FL350. All suspect an unexplained ghost target. Controller suspected possible military desert activity. Our TCASII equipment for that leg appeared to operate normally otherwise.

Original NASA ASRS Text

Title: TCASII TA RA CLB EVASIVE ACTION TAKEN FROM GHOST TARGET.

Narrative: ACR X RECEIVED TCASII TA AURALLY AND VISUALLY AT 2 O'CLOCK POS ON EHSI APPROX 20 MI. ATC HAD NOT RPTED ANY TFC. WE HAD NO DIAMOND TARGETS ON THE EHSI IN THAT POS PRIOR TO THE TA. SECONDS LATER THE TA BECAME AN RA, WITH THE COMMAND 'CLB, CLB NOW'. WE MANUALLY EXECUTED THE CLB FROM 35000 TO APPROX 35800 WHILE CAPT ASKED ATC IF HE HAD ANY TFC FOR US. HE RPTED NONE. THE RA AURAL AND VISUAL CEASED. NOTE: THE TA BECAME RA AT APPROX 10 MI AT 2 O'CLOCK. WE RETURNED TO CRUISE FL350. CTLR EXPRESSED NO SERIOUS CONCERN ABOUT OUR ALTDEV. HE NOTED THAT HE HAS HAD AS MANY AS 15 SIMILAR RPTS IN THE SAME AREA. ANOTHER PLT HAD JUST PREVIOUSLY RPTED A SIMILAR EVENT AT FL350. ALL SUSPECT AN UNEXPLAINED GHOST TARGET. CTLR SUSPECTED POSSIBLE MIL DESERT ACTIVITY. OUR TCASII EQUIP FOR THAT LEG APPEARED TO OPERATE NORMALLY OTHERWISE.

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.