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Air carrier medium large transport received a TCAS alert but never saw the traffic and ATC advised there was no traffic in the area of the reporter's aircraft. Flight crew climbed 350' because traffic was indicated 100' below clearance altitude.
| Attributes | |
| ACN | 169035 |
| Time | |
| Date | 199101 |
| Day | Fri |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : atl |
| State Reference | GA |
| Altitude | msl bound lower : 10000 msl bound upper : 10350 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : atl tower : ptk |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | climbout : intermediate altitude cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : instrument pilot : flight engineer pilot : commercial pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 10000 flight time type : 5000 |
| ASRS Report | 169035 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Events | |
| Anomaly | 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 |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
We departed atl and were cleared to 10000'. Approaching level off we received a traffic advisory on our TCAS system. This was followed by 2 more traffic advisories very close together. Position of reported traffic was 9 O'clock less than 1 mi and closing, with attitude difference 100' or less. TCAS was in TA mode and we felt sure that if it would have been in TA/RA mode a resolution advisory would have been indicated. I was in left seat and looked to 9 O'clock but did not see traffic. Pilot in right seat was flying. We climbed to 10350' as TCAS traffic was indicated to pass under us. We then returned to 1000' assigned altitude. We never sighted traffic indicated by TCAS. We asked atl departure control if they had traffic on their scope. They said they had no indicated traffic near our position. Since no traffic was sighted by us or was indicated by atl departure, we concluded TCAS traffic indication was either a small aircraft or an indication error by TCAS.
Original NASA ASRS Text
Title: ACR MLG RECEIVED A TCAS ALERT BUT NEVER SAW THE TRAFFIC AND ATC ADVISED THERE WAS NO TRAFFIC IN THE AREA OF THE REPORTER'S ACFT. FLT CREW CLIMBED 350' BECAUSE TRAFFIC WAS INDICATED 100' BELOW CLRNC ALT.
Narrative: WE DEPARTED ATL AND WERE CLRED TO 10000'. APCHING LEVEL OFF WE RECEIVED A TFC ADVISORY ON OUR TCAS SYS. THIS WAS FOLLOWED BY 2 MORE TFC ADVISORIES VERY CLOSE TOGETHER. POS OF RPTED TFC WAS 9 O'CLOCK LESS THAN 1 MI AND CLOSING, WITH ATTITUDE DIFFERENCE 100' OR LESS. TCAS WAS IN TA MODE AND WE FELT SURE THAT IF IT WOULD HAVE BEEN IN TA/RA MODE A RESOLUTION ADVISORY WOULD HAVE BEEN INDICATED. I WAS IN LEFT SEAT AND LOOKED TO 9 O'CLOCK BUT DID NOT SEE TFC. PLT IN RIGHT SEAT WAS FLYING. WE CLBED TO 10350' AS TCAS TFC WAS INDICATED TO PASS UNDER US. WE THEN RETURNED TO 1000' ASSIGNED ALT. WE NEVER SIGHTED TFC INDICATED BY TCAS. WE ASKED ATL DEP CTL IF THEY HAD TFC ON THEIR SCOPE. THEY SAID THEY HAD NO INDICATED TFC NEAR OUR POS. SINCE NO TFC WAS SIGHTED BY US OR WAS INDICATED BY ATL DEP, WE CONCLUDED TCAS TFC INDICATION WAS EITHER A SMA OR AN INDICATION ERROR BY TCAS.
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.