Narrative:

Shortly after takeoff climbing through 1;500 ft we received an RA on the nose of the aircraft with a commanded rate of descent. At approximately 1;000 ft further commands to increase rate of descent. At 800 ft the GPWS terrain warning occurred. Descent was stopped very shortly thereafter. ATC was alerted that we were complying with the RA and they immediately confirmed/notified us that there was no traffic in our vicinity. We opted to continue the climb after carefully checking the traffic. At 3;000 ft we received a TA with no associated yellow traffic symbol and no visible targets. We opted to select the rt transponder [TA only] and at approximately 6;000 ft another TA was received with no yellow targets on the 10 20 or 40 mile scale. After initial level off; dispatch and maintenance were contacted. Maintenance told us they showed no faults with the TCAS system and suggested pulling/resetting the TCAS circuit breaker (circuit breaker). We declined as there was no explanation given; or expected outcome for this request. Pulling and resetting circuit breaker's are in direct conflict with FM part 1 and the QRH in flight unless specified in a procedure. After careful consideration and coordination with dispatch we elected to return. An emergency was declared and we complied with all performance; overweight landing and emergency procedures. ATC gave special attention especially with regards to traffic. We received numerous TA's on arrival and approach. The wind was 350/19g28. We elected to delay the approach for acceptable winds as landing to the west would take approximately 45-50 minutes to coordinate. Overweight landing was a smooth centered in the touchdown zone. We used all available runway to minimize brake temperatures. Arff responded as a precautionary measure. We met with an avionics maintenance technician after arrival and discussed the problems with the TCAS at length. After reading our extensive write up and listening to our debrief; he grounded the aircraft without reservation.

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Original NASA ASRS Text

Title: B777 First Officer experiences a TCAS RA to descend at 1;500 FT on departure with the Captain as pilot flying. A descent is initiated until a terrain warning is issued at 800 FT and ATC indicates that there is no traffic in the area. After discussions with Maintenance the crew elects to return to the departure airport for an overweight landing.

Narrative: Shortly after takeoff climbing through 1;500 FT we received an RA on the nose of the aircraft with a commanded rate of descent. At approximately 1;000 FT further commands to increase rate of descent. At 800 FT the GPWS terrain warning occurred. Descent was stopped very shortly thereafter. ATC was alerted that we were complying with the RA and they immediately confirmed/notified us that there was no traffic in our vicinity. We opted to continue the climb after carefully checking the traffic. At 3;000 FT we received a TA with no associated yellow traffic symbol and no visible targets. We opted to select the RT transponder [TA only] and at approximately 6;000 FT another TA was received with no yellow targets on the 10 20 or 40 mile scale. After initial level off; Dispatch and Maintenance were contacted. Maintenance told us they showed no faults with the TCAS system and suggested pulling/resetting the TCAS Circuit Breaker (CB). We declined as there was no explanation given; or expected outcome for this request. Pulling and resetting CB's are in direct conflict with FM Part 1 and the QRH in flight unless specified in a procedure. After careful consideration and coordination with dispatch we elected to return. An emergency was declared and we complied with all performance; overweight landing and emergency procedures. ATC gave special attention especially with regards to traffic. We received numerous TA's on arrival and approach. The wind was 350/19G28. We elected to delay the approach for acceptable winds as landing to the west would take approximately 45-50 minutes to coordinate. Overweight landing was a smooth centered in the touchdown zone. We used all available runway to minimize brake temperatures. ARFF responded as a precautionary measure. We met with an avionics Maintenance Technician after arrival and discussed the problems with the TCAS at length. After reading our extensive write up and listening to our debrief; he grounded the aircraft without reservation.

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.