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Flight crew of a DC9-50 climbed in response to a TCASII RA during cruise only to find out from ATC that the target was level at a higher altitude. Their climb was stopped shortly due to the TCASII RA stopped and ATC advising that the only traffic nearby was confirmed level at a higher altitude.
| Attributes | |
| ACN | 422538 |
| Time | |
| Date | 199812 |
| Day | Thu |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : emg |
| State Reference | LA |
| Altitude | msl bound lower : 31000 msl bound upper : 31400 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | DC-9 50 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise other |
| Route In Use | enroute airway : zfw |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Experience | flight time last 90 days : 200 flight time total : 8500 flight time type : 1500 |
| ASRS Report | 422538 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : instrument pilot : flight engineer pilot : commercial |
| Experience | flight time last 90 days : 200 flight time total : 14500 flight time type : 2500 |
| ASRS Report | 422465 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Consequence | faa : reviewed incident with flight crew |
| Miss Distance | horizontal : 6000 vertical : 1600 |
| Supplementary | |
| Air Traffic Incident | other |
Narrative:
We were operating a flight from mem to sat. Approximately 20 mi south of emg at FL310 we received a TCASII TA. Our display indicated the intruder was 12:30 - 1 O'clock position and 6 mi 500 ft below our altitude. We contacted ATC to verify and then received an RA to 'climb, climb.' we immediately complied with the TCASII RA since we were IMC and did not have the aircraft in sight. ATC said that he did have an aircraft in that relative position but his altitude was FL330. ATC asked the other aircraft to verify his altitude was FL330, which it was. The RA ceased and we stopped our climb at FL314. We are required to comply with all RA's unless we can confirm that it is unsafe to do so, which we couldn't do since we were IMC. Earlier reports from other aircraft were of severe turbulence with 1 aircraft reporting an altitude excursion of 1000 ft. With this in mind, we had every reason to believe our TCASII. It is now obvious that our TCASII misread the other aircraft's altitude and issued a false and dangerous RA. ATC said that the other aircraft's mode C indicated FL330 the entire time.
Original NASA ASRS Text
Title: FLC OF A DC9-50 CLBED IN RESPONSE TO A TCASII RA DURING CRUISE ONLY TO FIND OUT FROM ATC THAT THE TARGET WAS LEVEL AT A HIGHER ALT. THEIR CLB WAS STOPPED SHORTLY DUE TO THE TCASII RA STOPPED AND ATC ADVISING THAT THE ONLY TFC NEARBY WAS CONFIRMED LEVEL AT A HIGHER ALT.
Narrative: WE WERE OPERATING A FLT FROM MEM TO SAT. APPROX 20 MI S OF EMG AT FL310 WE RECEIVED A TCASII TA. OUR DISPLAY INDICATED THE INTRUDER WAS 12:30 - 1 O'CLOCK POS AND 6 MI 500 FT BELOW OUR ALT. WE CONTACTED ATC TO VERIFY AND THEN RECEIVED AN RA TO 'CLB, CLB.' WE IMMEDIATELY COMPLIED WITH THE TCASII RA SINCE WE WERE IMC AND DID NOT HAVE THE ACFT IN SIGHT. ATC SAID THAT HE DID HAVE AN ACFT IN THAT RELATIVE POS BUT HIS ALT WAS FL330. ATC ASKED THE OTHER ACFT TO VERIFY HIS ALT WAS FL330, WHICH IT WAS. THE RA CEASED AND WE STOPPED OUR CLB AT FL314. WE ARE REQUIRED TO COMPLY WITH ALL RA'S UNLESS WE CAN CONFIRM THAT IT IS UNSAFE TO DO SO, WHICH WE COULDN'T DO SINCE WE WERE IMC. EARLIER RPTS FROM OTHER ACFT WERE OF SEVERE TURB WITH 1 ACFT RPTING AN ALT EXCURSION OF 1000 FT. WITH THIS IN MIND, WE HAD EVERY REASON TO BELIEVE OUR TCASII. IT IS NOW OBVIOUS THAT OUR TCASII MISREAD THE OTHER ACFT'S ALT AND ISSUED A FALSE AND DANGEROUS RA. ATC SAID THAT THE OTHER ACFT'S MODE C INDICATED FL330 THE ENTIRE TIME.
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.