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An MD80 TCAS had an apparent null bus fault which alerted an RA with traffic one mile; level at 32;000 ft. So in response the crew climbed to 33;000 ft before recognizing a false alert.
| Attributes | |
| ACN | 984391 |
| Time | |
| Date | 201112 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Environment | |
| Flight Conditions | IMC |
| Light | Dusk |
| Aircraft 1 | |
| Make Model Name | MD-83 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | TCAS Equipment |
| Person 1 | |
| Function | Pilot Not Flying First Officer |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Total 14500 |
| Person 2 | |
| Function | Pilot Flying Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Altitude Excursion From Assigned Altitude |
Narrative:
Cruising at 32;000 ft received a TCAS RA commanding a climb. TCAS showed an aircraft at 12 o'clock and approximately 1 mile; level and at our altitude. TCAS commanded a climb which captain/PF performed; while I notified ATC. ATC responded that he showed no conflicting traffic. We leveled at 33;000 ft; then when satisfied there was no threat; we returned to our assigned altitude of 32;000 ft. The TCAS never issued a TA; only an RA. It also never issued a; 'clear of conflict.' the totality of the events convinced us that the TCAS had issued a false warning and it was written up as such in the aircraft logbook.
Original NASA ASRS Text
Title: An MD80 TCAS had an apparent Null Bus fault which alerted an RA with traffic one mile; level at 32;000 FT. So in response the crew climbed to 33;000 FT before recognizing a false alert.
Narrative: Cruising at 32;000 FT received a TCAS RA commanding a climb. TCAS showed an aircraft at 12 o'clock and approximately 1 mile; level and at our altitude. TCAS commanded a climb which Captain/PF performed; while I notified ATC. ATC responded that he showed no conflicting traffic. We leveled at 33;000 FT; then when satisfied there was no threat; we returned to our assigned altitude of 32;000 FT. The TCAS never issued a TA; only an RA. It also never issued a; 'clear of conflict.' The totality of the events convinced us that the TCAS had issued a false warning and it was written up as such in the aircraft logbook.
Data retrieved from NASA's ASRS site as of April 2012 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.