EMB-170 flight crew reported Terrain Warning while on approach.
Synopsis
EMB-170 flight crew reported Terrain Warning while on approach.
Narrative
I was pilot flying (PF) going into ZZZ for a visual XXR. We broke off the arrival and shortly after were cleared for the visual approach north of the approach course. I set the final approach fix altitude and started the descent to 2200. I wanted to get down a little earlier because I noticed the FAF was a shorter final than the usual 5-6 mile final; and wanted to make sure I had that time in level to configure and slow to be stable. The aim point where I wanted to join the localizer at was at the ZZZZZ fix. I knew I had a Tower close into ZZZZZ that I wanted to reference for my turn; keeping proper vertical and horizontal distance from the Tower until established. I had the Tower in sight and noticed the path to turn outside of it put us flying over a hill. It was clear daytime VFR and I determined we had the proper vertical clearance to continue over the hill. We were level or leveling at 2200; speed 170-180; flaps two when we got a caution terrain warning due to flying over the hill. I disconnected the Autopilot; verbalized I had the Tower and terrain in sight; and started a very shallow climb of just 100-200 fpm as I had visual reference with the hill we were flying over. The terrain caution only lasted a few seconds as once we were past the hill the radar altimeter went back to indicating 1400ft. My eyes were mostly outside as I was keeping visual reference and joining the localizer; but the lowest I saw the radar altimeter get was 900-800 feet for a very brief moment as we crossed the peak of the hill. We elected to continue the approach as we had the time to continue configuring and slow to be stable by 1000 and did so with no other irregular events. Once on the ground we debriefed the whole approach; discussed what are manuals say about the situation; and how we could have prevented the caution for next time. Cause: I think the big cause was just a misjudgment on my part of the height the warning would sound along with a misjudgment of the hill. We cleared the hill with what I thought would be no issue but still got a warning. I was aware of the hill and surrounding obstacles; in sight the whole time and from miles out; just didn't think it would cause a terrain issue; and visually it did not pose a threat to the safety of the flight to me. Suggestions: All I can think about is a company page or reference page explaining that visual approach when coming in from the north could cause a terrain warning when joining between the FAF and IF. I also think myself I just need to play it safer than I already think just to be on the extra cautious side; so a warning doesn't ever occur in the future.
Second reporter narrative
I was the First Officer acting as pilot monitoring (PM) from ZZZ1-ZZZ. We were placed on the STAR in the left downwind for XXR at 3000 ft. The Captain/pilot flying (PF) and myself had the field in sight when they asked; so we were cleared for the visual approach. The Captain began a turn towards ZZZZZ and began a descent to 2200ft; which was the floor altitude at the final approach fix. As we were leveling off; or slightly thereafter; and as we approached a hill that we were visually clear of; we received two caution terrain" audible messages. The PF identified the obstacle and I saw it as well as the terrain; both of which were not factors to safe flight we determined. The radio altimeter dropped below 1;000 but then increased back to 1;400 once we were clear of the bluff; established on the final approach course. We then configured normally and had a stabilized approach. Once parked at the gate; we debriefed the messages received and discussed what we should've done differently.Cause: We briefed the ILS XXR approach as that's what the ATIS was advertising but were given a visual approach so we did not brief obstacles as part of our approach brief. We also descended preemptively and should've held 3;000 with the bluffs and obstacles until we were established on the final approach course or began a slow descent to 2;200 as we were joining.Suggestions: Even if you're expecting the ILS; just brief the obstacles that your flight path will take you nearby so you're prepared when you get cleared for a visual. Be mindful of your descents especially when dealing with terrain that isn't notated."
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.