EMB-145 crew reported receiving a 'TERRAIN TERRAIN PULL UP' GPWS warning while on a visual approach. Crew reported confusion with proper modes of automation and performed a go-around followed by a normal landing.
Synopsis
EMB-145 crew reported receiving a 'TERRAIN TERRAIN PULL UP' GPWS warning while on a visual approach. Crew reported confusion with proper modes of automation and performed a go-around followed by a normal landing.
Narrative
I was PM and the FO PF. This was my first trip as a CA and he was still relatively a new FO. Starting at the initial decent into ZZZ; things were normal. During the brief; we mentioned the threat of terrain; how there is a ridge prior to the airport; and also specifically the amount of GPWS events happen due to this ridge. Center gave us direct to the field and maintain 4300 ft. Once we hit 4300 ft; we had the field in sight and was cleared for the visual XX. At this point it was day VMC and we had the field and the ridge in sight. The FO called for FL22 and said he can go down to 3400ft for ZZZZZ and then he starting turning the ALT knob. I said No; not yet; we have that ridge below us; watch out for the MSA. At that point I looked down to add a PVOR (Precision VOR) thinking we were level. I looked up and saw we were descending so I said hold your ALT. He reached for the FGC (Flight Guidance Computer) and looked like he was trying to raise the ALT bug to the previous ALT; and that's when I noticed we were in pitch Mode. Then; I said hold your ALT; and I reached over and pressed ALT Hold. The FO disconnected the Auto Pilot and pulled up slightly but still continued a slight decent. Shortly after that; we got the TERRAIN TERRAIN PULL UP without the caution first. I had Terrain up on my side and there was never any red on my MFD (Multi-function Flight Display). As soon as I heard that I told the FO to Go Around. He seemed to slightly freeze and didn't make any adjustments. Next I said Go Now with more urgency and he then made a small thrust movement with a small pull back on the yoke but seemed overwhelmed in the moment. I instantly took controls of the AC; went full thrust and pulled back pretty abruptly. From the time I recognized he was descending to the time we got the aural warning was roughly only about 30 seconds.We climbed to 5000 ft and I told the First Officer to inform the Tower that we had a GPWS event and will need to be vectored back in towards runway. After the aircraft was stabilized; we cleaned up and continued with vectors towards XX. After we were cleaned up and stabilized; I asked the First Officer if he was okay and if he was ready to continue; and he confirmed. I maintained control of the aircraft while the First Officer continued as pilot monitoring. We continue the approach without incident after that.Cause: The FO did not effectively use the FGC; verify what the altitude was doing; or use the correct actions to solve the immediate issue. While being heads down I did not recognize the state the aircraft was in and failed to realize he was still descending when I told him not to. I believe due to the shock of the GPWS warning; the FO froze in the moment he needed to take action; resulting in me taking over the controls. Recommendation: Once we arrive to the hotel; me and the First Officer set in a secluded place and spoke about the event; what took place; and what the correct action would've been in this situation. I briefed him on the importance of knowing what your aircraft is doing; verifying on the FMA (Flight Mode Annunciator); and the importance of knowing obstacles and mountainous terrain in the vicinity. I also had a conversation with him about being able to utilize the auto pilot to its full ability; and that the best solution in the leveling off is selecting altitude hold instead of trying to disconnect and solve the problem himself hand flying.
Second reporter narrative
I was PF and CPT (Captain) was PM. This was the first trip of the CA. Flight was normal and per the company pages the PM had the terrain radar activated due to GPWS events in the area. Center had us descend to 4300 and direct the field. We were then cleared for the visual XX. I called for flaps 22 out of sequence to assist with reducing airspeed out of the descent. I started a descent to 3400 feet as that was the GS intercept altitude at ZZZZZ and we were visually clear of the terrain. PM was heads down to set up PVOR (Precision VOR). We start to descend past 3700 and PM mentions to hold your altitude. I move the altitude bug to 3600 feet and by that time the AP (Autopilot) was in pitch mode and it started to descend past 3600 feet. PM reaches over and presses he ALT button. Around that moment I disconnect the autopilot to manually fly the approach as the autopilot was not intending what I wanted it to do. I pull up slightly to arrest the rate of descent but was still descending because the runway as visual and we were visually well clear of terrain. At that moment TERRAIN TERRAIN PULL UP was annunciated. At first I froze because of the confusion of the alert and thought we were clear of obstructions. Verbal instructions by the PM were not heard due to EGPWS (Enhanced Ground Proximity Warning System) being louder and rather more jarring than anticipated. The PM's radar screen did not indicate any 'red' terrain. The PM elected to move the thrust levers to full and assumed control of the aircraft during the escape maneuver. I set the altitude bug to climb to 5000 feet as it was above the MSA to the nearest thousandth and we get radar vectors from center and do the full ILS into ZZZ without incident.Cause: is my failure to hit the ALT hold button at a more appropriate time to clear the ridge line above GPWS tolerances. Additionally a 200 foot tower on top of the ridge line may have triggered GPWS in an awkward position that gave a sense of not being 'well clear' of the ridge line as much as the crew was visually.'Recommendation: Suggestions are to make it more clear about the procedures concerning GWPS annunciations when visual obstructions are cleared in DVFR conditions. Per the FOM/AOM the escape maneuver that was learned in training is not required in DVFR conditions; but rather take action to assure terrain clearance. Additionally ZZZ Center cleared us to flight straight to the field to put us in a position closer to more undesirable terrain. In the past they have instead directed us to fly to a fix on the ILS to be in a better position to be set up for Runway XX. A dedicated Approach Controller at ZZZ can direct us away from the position we were in
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.