Air Carrier flight crew reported a momentary terrain warning triggered by turbulence during approach descent. Flight crew continued and landed safely.
Synopsis
Air Carrier flight crew reported a momentary terrain warning triggered by turbulence during approach descent. Flight crew continued and landed safely.
Narrative
We were descending into ROA and dealing with a wing anti ice fail message. We were in and out of clouds / icing conditions on the descent from 9000 to 6000. I had the FO ask for lower to try to exit icing conditions. ATC cleared us down to 5200' and said that was the lowest we could go due to the MVA in that area; which was enough to raise the OAT enough to exit icing conditions. At some point while southwest of the airport at 5200' and ATC on vectors for the RNAV 24 approach; we received what I think was a spurious; single 'terrain - pull up' GPWS activation. As I said; we were in and out of the clouds. The flight conditions were maybe MVFR or a little better at that moment; I had nothing presented on the Multi-function Flight Display (MFD) terrain page; and saw no terrain ahead - only behind us. What I think may have happened is; being that it was a pretty bumpy ride; and even though we were on the autopilot; the aircraft showed a momentary descent due to the turbulence; and as such; the GPWS thought that we really were descending when in fact we were not! After we received the notification; we continued on to a gusty RNAV approach in visual conditions.
Second reporter narrative
WG A/ice fail; ice cond-a/i inop in IMC while being vectored for RNAV 24 ROA. Referenced QRH. Asked ATC for lower to exit icing conditions per the QRH. Request denied. Asked again and instructed to descend and maintain 5200. Continued with QRH. Eventually exited icing and entered VMC. Received a terrain warning. Continued on with approach and landed safely in ROA.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.