Narrative:

While being vectored for an ILS xx; we were descending in IMC conditions from 3000ft to 2500ft. Conditions at the field were 2 miles visibility and overcast at 600 feet. We got an egpws terrain warning and initiated a climb in response. We told ATC that we were climbing to comply. We were assigned a turn and an altitude of 3500 feet. We subsequently received multiple warnings - including a bank angle warning (when our bank angle was between 10-15 degrees); the gear horn; and 'too low terrain.' we concluded that the RA (radio altimeter) was malfunctioning; and was the cause of the warnings. The warnings could not be silenced with the proximity override; or by disabling both DCU's. There is no QRH procedure for faulty warnings. We were troubleshooting based on our own experience; and pulled the radio altimeter circuit breaker; and the warnings stopped. We landed without declaring an emergency. The first issue I wanted to report was the malfunction of our egpws warnings; but I also wanted to convey the secondary issues that arose as a result of the first problem - which was that we landed without verifying our landing distance was sufficient. I also felt that my communication with approach was not very effective. With the time-critical nature of our trouble-shooting and response to the warnings; I couldn't fully explain the situation - and I imagine they wouldn't expect us to have terrain warnings occur at our position and altitude. We were initially unable to silence the warnings; which also created confusion and difficulty in communicating. I asked for a heading and an altitude to maintain so that we could focus our attention on the aircraft issues. The controller essentially vectored us in a box pattern; and then instructed us to intercept the localizer. At this point; we had just found the RA circuit breaker; and were re-evaluating our ability to shoot the approach. The controller cleared us for the approach; and then verified that we were able to accept the approach. I told the captain that we could ask for more time; since we had plenty of fuel; but he felt we were ready for it. We shot the approach without incident. However; in retrospect; we never verified that our landing distance was sufficient; according to the QRH procedure for a failed radio altimeter. I estimated an increased landing distance multiplier; and compared it to our available runway; but never got the technical numbers. We discussed the possible use of flight spoilers for better landing performance. The MEL listed a deferral for 22-00-0 (CAT 2 not authorized.) there are no operational or maintenance procedures for this deferral. The dmil lists the description for the deferral as 'repetitive radio altitude discrepancy;' and it was entered in early oct. Although repetitive radio altitude was the reason for a deferral; the radio altimeter was not deferred because it can't be deferred. Since the deferral date; (when; according to maintenance control; a similar incident occurred) it has either been fixed; or the components were tested with no defaults found. In mid october; a crew experienced another similar series of GPWS and terrain warnings. This is the 3rd time in 2 weeks that this aircraft has had these problems. Although I don't have access to the full records; I was told that there were additional write-ups involving the radio altimeter it may not have been a big deal if conditions were better; but we were partially configured for our approach; close to the ground; below the MSA; in solid IMC conditions; initiating abrupt maneuvers to respond; and being forced to troubleshoot a problem with no written QRH guidance; while the passengers could clearly hear the warnings and were unnerved by the rapid changes in pitch and power. It seems to me that the first occurrence of this issue should have dictated more than simply deferring the CAT 2. For the second issue; I felt that my communication with approach was not very effective. With the time-criticalnature of our trouble-shooting and response to the warnings; I couldn't fully explain the situation to the approach controller.

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Original NASA ASRS Text

Title: A CRJ700 with a Repetitive Radio Altimeter malfunction received 'Too Low Terrain'; bank angle and gear horn warnings during approach. The approach was discontinued for trouble shooting and pulling the Radio Altimeter circuit breaker.

Narrative: While being vectored for an ILS XX; we were descending in IMC conditions from 3000ft to 2500ft. Conditions at the field were 2 miles visibility and overcast at 600 feet. We got an EGPWS Terrain warning and initiated a climb in response. We told ATC that we were climbing to comply. We were assigned a turn and an altitude of 3500 feet. We subsequently received multiple warnings - including a bank angle warning (when our bank angle was between 10-15 degrees); the gear horn; and 'TOO LOW TERRAIN.' We concluded that the RA (Radio Altimeter) was malfunctioning; and was the cause of the warnings. The warnings could not be silenced with the PROXIMITY override; or by disabling both DCU's. There is no QRH procedure for faulty warnings. We were troubleshooting based on our own experience; and pulled the Radio Altimeter circuit breaker; and the warnings stopped. We landed without declaring an emergency. The first issue I wanted to report was the malfunction of our EGPWS warnings; but I also wanted to convey the secondary issues that arose as a result of the first problem - which was that we landed without verifying our landing distance was sufficient. I also felt that my communication with approach was not very effective. With the time-critical nature of our trouble-shooting and response to the warnings; I couldn't fully explain the situation - and I imagine they wouldn't expect us to have terrain warnings occur at our position and altitude. We were initially unable to silence the warnings; which also created confusion and difficulty in communicating. I asked for a heading and an altitude to maintain so that we could focus our attention on the aircraft issues. The controller essentially vectored us in a box pattern; and then instructed us to intercept the localizer. At this point; we had just found the RA circuit breaker; and were re-evaluating our ability to shoot the approach. The controller cleared us for the approach; and then verified that we were able to accept the approach. I told the captain that we could ask for more time; since we had plenty of fuel; but he felt we were ready for it. We shot the approach without incident. However; in retrospect; we never verified that our landing distance was sufficient; according to the QRH procedure for a failed Radio Altimeter. I estimated an increased landing distance multiplier; and compared it to our available runway; but never got the technical numbers. We discussed the possible use of flight spoilers for better landing performance. The MEL listed a deferral for 22-00-0 (CAT 2 Not Authorized.) There are no operational or maintenance procedures for this deferral. The DMIL lists the description for the deferral as 'Repetitive Radio ALT Discrepancy;' and it was entered in early Oct. Although repetitive radio altitude was the reason for a deferral; the Radio Altimeter was not deferred because it can't be deferred. Since the deferral date; (when; according to maintenance control; a similar incident occurred) it has either been fixed; or the components were tested with no defaults found. In mid October; a crew experienced another similar series of GPWS and terrain warnings. This is the 3rd time in 2 weeks that this aircraft has had these problems. Although I don't have access to the full records; I was told that there were additional write-ups involving the Radio Altimeter It may not have been a big deal if conditions were better; but we were partially configured for our approach; close to the ground; below the MSA; in solid IMC conditions; initiating abrupt maneuvers to respond; and being forced to troubleshoot a problem with no written QRH guidance; while the passengers could clearly hear the warnings and were unnerved by the rapid changes in pitch and power. It seems to me that the first occurrence of this issue should have dictated more than simply deferring the CAT 2. For the second issue; I felt that my communication with approach was not very effective. With the time-criticalnature of our trouble-shooting and response to the warnings; I couldn't fully explain the situation to the approach controller.

Data retrieved from NASA's ASRS site as of April 2012 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.