Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP)
Confusion
Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude
Aircraft Equipment Problem Dissipated; Flight Crew Took Evasive Action
Aircraft
At 4;000 FT and just as we are handed off from Cascade Approach to Tower I noticed that a blue dot showing a 0 on my TCAS had popped up from no where. I looked outside to see if I could see anything since there was no traffic reported by Approach or that we never had an aircraft on the TCAS on our descent. From the time it took for me to register that something was on the TCAS we got a RA to climb. I followed the guidance to climb. After a few seconds the RA stopped and there was no longer anything on our TCAS. I notified Cascade Approach since we never went to Tower. We climbed about 1;500 FT on our maneuver. Cascade said they showed no aircraft on their radar. We were vectored back to final and given a phone number to call. We had no other problems on approach. After getting to the gate and finishing the check list. I call Cascade and talked to the supervisor. He said he was standing next to the Controller as soon as he told him we were complying with the RA. He too said that he saw nothing on the screen. I told him we didn't see anything either but had to comply. He stated he was going to submit his report and I said the same. I can only guess it was a glitch in the TCAS system since we never saw the aircraft in question and that it popped right on the screen from no where.
Air Carrier Captain describes the sudden appearance of a TCAS target; followed quickly by a RA to climb. ATC is advised and the target suddenly disappears after climbing 1;500 FT. ATC never had a target on Radar and the crew never had a visual sighting.