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While level at FL350 the flight crew of a B737-300 responded to an apparently aberrant TCAS 'climb' warning. The only traffic in the vicinity was a company aircraft level at FL360.
| Attributes | |
| ACN | 1100917 |
| Time | |
| Date | 201307 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZID.ARTCC |
| State Reference | IN |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B737-300 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Traffic Collision Avoidance System (TCAS) |
| Person 1 | |
| Function | Pilot Not Flying Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 233 Flight Crew Type 9000 |
| Person 2 | |
| Function | Pilot Flying First Officer |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy |
Narrative:
While cruising at FL350; we received a TCAS RA directing a climb. The ivsi gave a green arc between 700 and 1;000 fpm climb and a red arc beyond that. The target aircraft was showing coincident with our location; however; while complying with the RA; neither pilot noticed the threat aircraft displayed on the ivsi was directly above us. (We didn't see the 'plus' symbol next to the target as it was mixed in with our aircraft symbol.) we complied with the RA and initiated a climb. We received a clear of conflict almost immediately after initiating the climb. Our altitude deviation was 100 ft to FL351 (35;100 ft.) I notified ATC of the RA and our maximum deviation. I told ATC we were clear and returning to FL350. ATC had only one other aircraft in the vicinity. Company XXX was level at his cruise altitude FL360. At the time of the RA; he was directly above us. Yet; our RA wanted a climb into the traffic. No other traffic was in the area and company XXX did not get any TCAS warning either TA or RA. Upon landing at bwi; maintenance was notified and the TCAS system was entered into the logbook as a discrepancy. I believe this was a malfunction of the TCAS.
Original NASA ASRS Text
Title: While level at FL350 the flight crew of a B737-300 responded to an apparently aberrant TCAS 'climb' warning. The only traffic in the vicinity was a company aircraft level at FL360.
Narrative: While cruising at FL350; we received a TCAS RA directing a climb. The IVSI gave a green arc between 700 and 1;000 fpm climb and a red arc beyond that. The target aircraft was showing coincident with our location; however; while complying with the RA; neither pilot noticed the threat aircraft displayed on the IVSI was directly ABOVE us. (We didn't see the 'plus' symbol next to the target as it was mixed in with our aircraft symbol.) We complied with the RA and initiated a climb. We received a clear of conflict almost immediately after initiating the climb. Our altitude deviation was 100 FT to FL351 (35;100 FT.) I notified ATC of the RA and our maximum deviation. I told ATC we were clear and returning to FL350. ATC had only one other aircraft in the vicinity. Company XXX was level at his cruise altitude FL360. At the time of the RA; he was directly ABOVE us. Yet; our RA wanted a climb INTO the traffic. No other traffic was in the area and Company XXX did not get any TCAS warning either TA or RA. Upon landing at BWI; Maintenance was notified and the TCAS system was entered into the logbook as a discrepancy. I believe this was a malfunction of the TCAS.
Data retrieved from NASA's ASRS site as of July 2013 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.