Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 250; Flight Crew Total 12000; Flight Crew Type 2000
Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Provided Assistance; Flight Crew Took Evasive Action
Aircraft; Human Factors
We were being vectored for the ILS 8 to BUR. About 20 miles northwest of the field. We were assigned and were descending to 5;000. About 5;300 feet; our GPWS announced 'Terrain; Terrain; Pull UP.' I kicked off the autopilot and climbed aggressively in response. By the time the alert was silenced; we were at about 6;500 feet.We notified ATC; who didn't seem too perturbed; and responded by saying 'minimum vectoring altitude in your area is XX feet' (don't remember the number but it was well below us.) We realized with certainty what I had initially suspected - we were never near terrain and were at a safe altitude at all times. In trying to figure out the issue; and determine why our gear horn was also sounding at the same time; I realized that my radar altimeter showed 0 feet. It had obviously malfunctioned and given the false GPWS warning. We were able to continue our approach and land without incident.We deviated from our ATC clearance; and as it turned out it was unnecessary to do so; but when you're in IMC and know that you're in high terrain; when that GPWS tells you to pull up; you don't hesitate; you hit the gas and get out of there. We did what we had to do; what we are trained to do. It was just good that it was only a malfunction and not a real safety hazard; and good that no conflict was created with other aircraft.
[Report narrative contained no additional information.]
Air carrier flight crew experienced a seemingly false GPWS warning due to mechanical malfunction.