Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 228; Flight Crew Total 3680; Flight Crew Type 1613
Confusion; Distraction; Time Pressure
Aircraft Equipment Problem Less Severe; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Provided Assistance; Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification; Flight Crew FLC Overrode Automation
Aircraft
During climb out in night IMC through 10;000 ft. at 250 kts; ATC gave direct to RAYNR and mentioned precipitation ahead. While scaling out to about 40 miles and working radar and evaluating course change; got 'Traffic' followed instantly by 'maintain vertical speed' PFD had red pitch avoid areas. Within about 3 seconds command switched to descend with TCAS RA red boxes on PFD commanding a descent.  This command led me to believe TCAS was communicating and coordinating with another airplane. Seeing red I looked outside while also ranging down the scale I was on as I  had red target on our airplane apex. During climb/descent I use relative altitude setting and I was seeing 00 to +01.  Pilot Flying descended per RA which was a rapid descent below 10;000 ft. The RA would clear momentarily without 'clear of conflict' and came back on again with descend type command after a few seconds advised ATC that we had descended per an RA and asked about traffic. Said none. Stabilized at 7;000 ft. and advised and requested climb again. This was followed by the 3rd RA . With ATC saying no traffic I switched to TA only as it was seeming this was a false traffic target. Training leads you to follow your training and work with the TCAS system. In the back of my mind I did consider a random VFR aircraft could have been trying to get around weather near us; so I was trusting the TCAS system. Later during climb out switched to RT transponder and after level off checked maintenance history with Maintenance Control phone patch. I noticed during preflight RT transponder was active. I switched it to left per SOP as both were available.
B777 Captain reported a TCAS problem that resulted in numerous erroneous alerts.