Air carrier flight crew reported receiving an obstacle alert during circle-to-land at DCA airport. Flight crew corrected their altitude and continued to landing.
Synopsis
Air carrier flight crew reported receiving an obstacle alert during circle-to-land at DCA airport. Flight crew corrected their altitude and continued to landing.
Narrative
We were a repo flight from ZZZ1 to DCA. We were cleared Mount Vernon Visual to Runway 1 by Approach. When we switched over to Tower; they asked if we were able Runway 33. The First Officer (FO) was pilot flying and had briefed the circle to 33; we also ran numbers for 33 previously and had the landing distance available. We accepted circle 33 and were cleared to land. We crossed the Woodrow Wilson bridge at 1;000 and turned right towards Highway I-295 to stay on the east side. We were configured at 1;000 and it was day VMC. The pilot flying (PF) asked me to remove his flight director as he continued the descent. Roughly a half mile from the 1.5 mile final; we received and obstacle call. The PF implemented corrective actions and added power/climbed until the call went away roughly 5 seconds later. We had the obstacle in sight the whole time; it was the top of the grassy hill just east of Highway I-295. The PF maintained level until turning final and intercepting the visual path to Runway 33. Once on path we were stable at 500 and the landing and taxi in were uneventful.An expected altitude for the Runway 33 1.5 mile final would help in judging the descent rate that would line you up properly for Runway 33 at an appropriate altitude.
Second reporter narrative
I was pilot flying (PF) and Captain was pilot monitoring (PM). During the brief for visual to Runway 1 into DCA we also briefed the possibility of a circle to Runway 33. The 1;000 ft. suggested altitude at the bridge was noted and I briefed that while circling; I would keep the 3 degree descent for the circle as there were no notes for another suggested altitude or glidepath in the circle to land 33. DCA Tower asked if we could accept a circle to Runway 33 and Captain said we were able. Captain asked if I would like for him to give me slope guidance past the bridge during the circle on base. When we noticed that we were going to be low; I leveled off. As we leveled; we got an obstacle alert into a rising terrain on the base leg just before beginning our turn to final. We were visual and saw we were well clear of the obstacles. We turned final and maintained altitude until intercepting the PAPI. During final on 33; we also received a glide slope warning for our Runway 1 approach.There are several altitude references and configuration suggestions for the DCA River Visual but only the 1;000 ft. suggestion while on final for 1 before circling to 33. I think a note that a shallower descent is required or a suggested altitude for the turn to final would be helpful.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.