Narrative:

Aircraft on downwind vectors for ILS. At approx. 3500 MSL captain's radio alt began fluctuations/readings of 1000' AGL w/ +/- 1500 foot deviations up and down. Intermittent GPWS 'terrain' warnings began. Even though it was an obvious malfunction indication; the flight was in IMC so the escape maneuver was initiated. The warning stopped during escape almost immediately; followed by more RA fluctuations on ca pfd. First officer side did not indicate any abnormality or RA issues throughout event. Flight deviated from ATC clearance (assigned altitude) during maneuver; ATC was advised during climb. After warnings stopped; altitudes were re-verified to be correct and safe; and approach vectors were continued.as a company we need to be more proactive in fixing GPWS/radar alt. Faults; not just 'clearing' the malfunction(s). This was a repeat write-up that was not troubleshot in any detail according to the maintenance log. This can create two hazards: 1. False warnings leading to unnecessary go-arounds; etc.; as in this case; and 2. Conditioning crews not to take GPWS warnings seriously; as many times the event is dismissed due to repeat write ups.it is necessary to always consider these warnings real during IMC and nights conditions; and I will continue to do so. There is no time to examine and diagnose if the warning is real or not. GPWS/radio alt. Faults must be corrected more quickly so as to avoid these scenarios. It is worth noting that as of my last involvement in this case with this airplane; maintenance was planning to fly a new radio alt. Box to [us] and install it there after only two write-ups. If this came to pass; then 'great job' to maintenance for fixing this quickly this time. This is a safety-critical system and multiple 'can not duplicates' create more hazards.

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Original NASA ASRS Text

Title: CRJ-700 Captain reported receiving erroneous GPWS warnings on an approach in IMC; resulting in deviation from assigned altitude. Reporter was critical of company Maintenance response to this ongoing equipment malfunction.

Narrative: Aircraft on downwind vectors for ILS. At approx. 3500 MSL Captain's radio alt began fluctuations/readings of 1000' AGL w/ +/- 1500 foot deviations up and down. Intermittent GPWS 'Terrain' warnings began. Even though it was an obvious malfunction indication; the flight was in IMC so the escape maneuver was initiated. The warning stopped during escape almost immediately; followed by more RA fluctuations on CA PFD. F/O side did not indicate any abnormality or RA issues throughout event. Flight deviated from ATC clearance (assigned altitude) during maneuver; ATC was advised during climb. After warnings stopped; altitudes were re-verified to be correct and safe; and approach vectors were continued.As a company we need to be more proactive in fixing GPWS/radar alt. faults; not just 'clearing' the malfunction(s). This was a repeat write-up that was not troubleshot in any detail according to the maintenance log. This can create two hazards: 1. False warnings leading to unnecessary go-arounds; etc.; as in this case; and 2. conditioning crews not to take GPWS warnings seriously; as many times the event is dismissed due to repeat write ups.It is necessary to always consider these warnings real during IMC and nights conditions; and I will continue to do so. There is no time to examine and diagnose if the warning is real or not. GPWS/radio alt. faults must be corrected more quickly so as to avoid these scenarios. It is worth noting that as of my last involvement in this case with this airplane; Maintenance was planning to fly a new radio alt. box to [us] and install it there after only two write-ups. If this came to pass; then 'great job' to Maintenance for fixing this quickly this time. This is a safety-critical system and multiple 'can not duplicates' create more hazards.

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.