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An air carrier B737 at FL350 receives a TCASII RA and descends. The controller advises the pilot that the nearest aircraft is 12 mi away and no factor. The aircraft returns to FL350.
| Attributes | |
| ACN | 331630 |
| Time | |
| Date | 199603 |
| Day | Tue |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : obh |
| State Reference | NE |
| Altitude | msl bound lower : 35000 msl bound upper : 35000 |
| Aircraft 1 | |
| Controlling Facilities | artcc : zmp |
| Operator | common carrier : air carrier |
| Make Model Name | B737-300 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller radar : 8 |
| ASRS Report | 331630 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : took evasive action flight crew : returned to intended course or assigned course other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | other |
Narrative:
Air carrier X, a B73SR was en route to den at FL350. At the time, I had approximately 25 aircraft on frequency. Air carrier X said 'center, air carrier X is responding to an RA, we are descending.' being extremely busy I didn't hear the call sign and stated 'say again.' air carrier X repeated the previous remark. I replied 'air carrier X, roger -- I have no traffic for you.' at this time there were no aircraft within 10 mi of air carrier X at any altitude in my airspace (FL240-FL350). Also, I did not observe anyone at FL370. Air carrier X said 'I was showing someone off of my left.' I then called traffic to air carrier X at 11 O'clock and 22 mi at FL330. Air carrier X said 'we're in the climb to FL350.' I said 'air carrier X, roger.' then I called the 2 nearest aircraft at FL350. One was 10 O'clock 18 mi, the other 6 O'clock and 12 mi. Air carrier X then called level at FL350 and no further conversation about the event took place. No loss of separation occurred. I have no idea why his TCASII showed a false intruder!
Original NASA ASRS Text
Title: AN ACR B737 AT FL350 RECEIVES A TCASII RA AND DSNDS. THE CTLR ADVISES THE PLT THAT THE NEAREST ACFT IS 12 MI AWAY AND NO FACTOR. THE ACFT RETURNS TO FL350.
Narrative: ACR X, A B73SR WAS ENRTE TO DEN AT FL350. AT THE TIME, I HAD APPROX 25 ACFT ON FREQ. ACR X SAID 'CTR, ACR X IS RESPONDING TO AN RA, WE ARE DSNDING.' BEING EXTREMELY BUSY I DIDN'T HEAR THE CALL SIGN AND STATED 'SAY AGAIN.' ACR X REPEATED THE PREVIOUS REMARK. I REPLIED 'ACR X, ROGER -- I HAVE NO TFC FOR YOU.' AT THIS TIME THERE WERE NO ACFT WITHIN 10 MI OF ACR X AT ANY ALT IN MY AIRSPACE (FL240-FL350). ALSO, I DID NOT OBSERVE ANYONE AT FL370. ACR X SAID 'I WAS SHOWING SOMEONE OFF OF MY L.' I THEN CALLED TFC TO ACR X AT 11 O'CLOCK AND 22 MI AT FL330. ACR X SAID 'WE'RE IN THE CLB TO FL350.' I SAID 'ACR X, ROGER.' THEN I CALLED THE 2 NEAREST ACFT AT FL350. ONE WAS 10 O'CLOCK 18 MI, THE OTHER 6 O'CLOCK AND 12 MI. ACR X THEN CALLED LEVEL AT FL350 AND NO FURTHER CONVERSATION ABOUT THE EVENT TOOK PLACE. NO LOSS OF SEPARATION OCCURRED. I HAVE NO IDEA WHY HIS TCASII SHOWED A FALSE INTRUDER!
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.