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Dash-8 first officer reported receiving an apparent erroneous TCAS RA command on arrival during a period unable to contact ATC.
| Attributes | |
| ACN | 1392872 |
| Time | |
| Date | 201607 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | Dash 8 Series Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Initial Approach |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Traffic Collision Avoidance System (TCAS) |
| Person 1 | |
| Function | First Officer |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | ATC Issue All Types Aircraft Equipment Problem Critical Conflict Airborne Conflict Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Published Material / Policy |
| Miss Distance | Vertical 500 |
Narrative:
While arriving into ZZZ we were told to contact final approach. We switched over to the new frequency and called multiple times with no response. We noticed traffic on our TCAS moving towards us at 4500 ft. We were at 4000 ft. We had the traffic in sight; which was a helicopter. We were still unable to get ahold of approach. Within seconds the traffic that was called out to us as a 'maintain vertical speed' by our TCAS became a 'monitor vertical speed'. Traffic was descending into us and was inside the bubble on the TCAS display. It went from 400 ft above; to 300 ft; to 200 ft. We had him in sight the entire time. We received an RA to 'adjust vertical speed' and climb 200-500 fpm. Immediately the captain and I agreed that was not at all appropriate as the traffic was slowly descending from above onto and towards us. We pushed the nose over and started a descent and turn away from the oncoming traffic. It was without a doubt in my mind the correct maneuver to keep the situation from progressing towards the worse. After receiving a clear of conflict indication and watching the traffic pass overhead; we returned to our assigned altitude of 4000 ft and heading. Shortly after that approach finally responded to our calls and we reported the incident to them.
Original NASA ASRS Text
Title: Dash-8 First Officer reported receiving an apparent erroneous TCAS RA command on arrival during a period unable to contact ATC.
Narrative: While arriving into ZZZ we were told to contact final approach. We switched over to the new frequency and called multiple times with no response. We noticed traffic on our TCAS moving towards us at 4500 ft. We were at 4000 ft. We had the traffic in sight; which was a helicopter. We were still unable to get ahold of approach. Within seconds the traffic that was called out to us as a 'maintain vertical speed' by our TCAS became a 'monitor vertical speed'. Traffic was descending into us and was inside the bubble on the TCAS display. It went from 400 ft above; to 300 ft; to 200 ft. We had him in sight the entire time. We received an RA to 'adjust vertical speed' and climb 200-500 fpm. Immediately the Captain and I agreed that was NOT AT ALL appropriate as the traffic was slowly descending from above onto and towards us. We pushed the nose over and started a descent and turn away from the oncoming traffic. It was without a doubt in my mind the correct maneuver to keep the situation from progressing towards the worse. After receiving a clear of conflict indication and watching the traffic pass overhead; we returned to our assigned altitude of 4000 ft and heading. Shortly after that approach finally responded to our calls and we reported the incident to them.
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.