A319 first officer reported receiving a GPWS terrain warning on a night IMC approach into bzn; even ...

Narrative:

I am submitting this report in response to our terrain warning and subsequent escape maneuver while descending into bzn. Prior to the top of descent; the captain fully briefed the arrival; approach (with emphasis on the MSA quadrants and terrain threats); in addition to go-around and special missed procedures. We retrieved landing data for runway 12 and it showed us legal to land on that runway given the current airport conditions. On descent we got a 2500 feet call out at around 17000 feet. We verified our position; current altimeter setting and continued our descent.on the arrival into bzn in night IMC; we were handed over to big sky approach. Upon contact we were given a clearance to the kicdo fix and descent clearance to 11000 feet. The captain continued our descent using full automation. At approximately 11500 feet we got a 'terrain; terrain' followed by a 'terrain...pull up'. The captain immediately initiated the CFIT escape maneuver and confirming our positive recovery state of the aircraft; I notified ATC of our condition. At around 11800 feet the warnings stopped and we leveled at 12000 feet. We checked our position and confirmed that we were where we should be. In addition; we both observed that no indication on either terrain map and briefed a possible reliability problem. We were issued further descent clearances in accordance with the published approach and continued to bzn safely.

Original NASA ASRS Text

Title: A319 First Officer reported receiving a GPWS terrain warning on a night IMC approach into BZN; even though they appeared to be at a proper altitude for their position.

Narrative: I am submitting this report in response to our terrain warning and subsequent escape maneuver while descending into BZN. Prior to the top of descent; the Captain fully briefed the arrival; approach (with emphasis on the MSA quadrants and terrain threats); in addition to go-around and special missed procedures. We retrieved landing data for runway 12 and it showed us legal to land on that runway given the current airport conditions. On descent we got a 2500 feet call out at around 17000 feet. We verified our position; current altimeter setting and continued our descent.On the arrival into BZN in night IMC; we were handed over to Big Sky Approach. Upon contact we were given a clearance to the KICDO fix and descent clearance to 11000 feet. The Captain continued our descent using full automation. At approximately 11500 feet we got a 'Terrain; Terrain' followed by a 'Terrain...Pull Up'. The Captain immediately initiated the CFIT escape maneuver and confirming our positive recovery state of the aircraft; I notified ATC of our condition. At around 11800 feet the warnings stopped and we leveled at 12000 feet. We checked our position and confirmed that we were where we should be. In addition; we both observed that no indication on either terrain map and briefed a possible reliability problem. We were issued further descent clearances in accordance with the published approach and continued to BZN safely.

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.

Attributes
ACN	1319126
Time
Date	201512
Place
Locale Reference	BZN.Airport
State Reference	MT
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Make Model Name	A319
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Flight Plan	IFR
Component
Aircraft Component	GPWS
Person 1
Function	First Officer Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 160 Flight Crew Type 721
Events
Anomaly	Aircraft Equipment Problem Less Severe Inflight Event / Encounter CFTT / CFIT

A319 first officer reported receiving a GPWS terrain warning on a night IMC approach into bzn; even though they appeared to be at a proper altitude for their position.