B737-800
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Air Traffic Control Military 20; Air Traffic Control Radar 20; Air Traffic Control Supervisory 10; Flight Crew Last 90 Days 29; Flight Crew Total 14000; Flight Crew Type 6590
Human-Machine Interface; Training / Qualification; Distraction; Confusion
Aircraft Equipment Problem Critical
Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Aircraft
Had a phantom TA followed by a RA. All were phantom and required a descent and then a climb on final. Finally for sure it was fake and we just had to fly with it on. It went away at 1;500 FT or so.
The Reporter stated that his aircraft type was a B737-800 which he has many flight hours in and has never seen this type event before. They were at 3;300 FT flying downwind and were given a 90 degree turn for a vector crosswind to final when the TCAS alerted TRAFFIC. The Reporter expanded the TCAS range and initially did not see traffic until a RA was displayed directly in front of the aircraft with a DESCEND command. The Reporter; the flying pilot; began a descent but the Captain became alarmed by the airspeed increase and the flaps 5 speed limit. Additional confusion ensued because of the frequency change to Tower. ATC reported helicopter traffic at 300 FT but that could not have been the traffic displayed. The TCAS then commanded CLIMB but both pilots realized at that time the false TCAS commands and continued the approach to a normal landing.
Received TCAS TA followed by an RA turning final to Runway 9. Followed TCAS guidance and reported to ATC. Landed normally. No traffic was observed.
A B737-800 crew reported a TCAS null bus fault with a DESCEND then CLIMB command at 3;300 FT while being vector crosswind to final.