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Shortly after a B757 departed the TCAS began reporting an RA with no traffic in the area. The alert ceased and the crew climbed to cruise altitude where another phantom RA event alerted. A null bus fault was assumed.
| Attributes | |
| ACN | 1236129 |
| Time | |
| Date | 201501 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Aircraft 1 | |
| Make Model Name | B757 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Climb Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Transponder |
| Person 1 | |
| Function | Captain Pilot Not Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 115 Flight Crew Total 21200 Flight Crew Type 6500 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe |
Narrative:
After departing we were being vectored when we got an RA. We responded by executing a 1G downward pitch as directed by the TCAS prompt. We reported RA to ATC; who had no traffic within 10 miles. TCAS indicated anon transponder equipped target was +200 feet above us. I never saw the traffic in question. In addition; the TCAS alert was nonstandard as it called 'traffic; traffic' but commanded us down; indicated on the ADI. We climbed back toward the altitude assigned. We never got a clear of conflict message. The RA simply disappeared.after leveling in cruise; we got another RA with this time a 'descend; descend' prompt and ADI indications for another no transponder equipped aircraft. We could not see and aircraft and ATC had no target. RA continued for 3-5 minutes until it disappeared. We contacted maintenance; wrote up the a/C and deactivated TCAS.
Original NASA ASRS Text
Title: Shortly after a B757 departed the TCAS began reporting an RA with no traffic in the area. The alert ceased and the crew climbed to cruise altitude where another phantom RA event alerted. A null bus fault was assumed.
Narrative: After departing we were being vectored when we got an RA. We responded by executing a 1G downward pitch as directed by the TCAS Prompt. We reported RA to ATC; who had no traffic within 10 miles. TCAS indicated anon transponder equipped target was +200 feet above us. I never saw the traffic in question. In addition; the TCAS alert was nonstandard as it called 'traffic; traffic' but commanded us down; indicated on the ADI. We climbed back toward the altitude assigned. We never got a clear of conflict message. The RA simply disappeared.After leveling in cruise; we got another RA with this time a 'descend; descend' prompt and ADI indications for another no transponder equipped aircraft. We could not see and aircraft and ATC had no target. RA continued for 3-5 minutes until it disappeared. We contacted maintenance; wrote up the A/C and deactivated TCAS.
Data retrieved from NASA's ASRS site 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.