Large Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 109; Flight Crew Type 310
Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude
Aircraft Equipment Problem Dissipated; Flight Crew Took Evasive Action
Aircraft; Weather
During our approach into Bozeman Montana we were cleared direct to KICDO and to descend to 11;000 feet by Big Sky Approach. Before reaching KICDO from the east at approximately 11;500 feet during our descent we received a terrain warning followed immediately by a terrain pull up warning. I executed the escape maneuver by disconnecting the auto pilot and putting the aircraft into Go Around mode. Our display showed no color terrain indication of any kind during this time. We climbed to 12;000 which is higher than the MSA in that sector and the audio warning stopped. Once we confirmed the aircraft status; we notified Big Sky ATC of the warning indication and of our new altitude. We stayed at 12;000 feet until ATC cleared us down to 8100 feet and turned us on to final for the final approach to runway 12. At the time of the approach the weather condition was snowing. Prior to this event while cruising at 17;000; we had an automated 2;500 foot call out. We can only attribute this to the snowing condition with the radar altimeter.No other additional indication occurred after the terrain warning. We continued the approach and landed without any further incident. Upon contacting Big Sky Approach by phone; I was informed that this abnormal indication have occurred to other aircraft in this area of operation in the past which is north of the airport. We show no terrain indication on either of our displays. Considering the lack of indication on our display and the fact that other aircraft have experience similar indications it seems to be an area of erroneous EGWS Indication.
Air carrier Captain reported an erroneous EGPWS Indication north of BZN during descent to 11000 feet near the KICDO intersection. Evasive action is taken but no high terrain is actually present. ATC indicated that other aircraft have experienced similar anomalies in that area.