EMB-145 flight crew reported receiving GPWS warning on approach.
Synopsis
EMB-145 flight crew reported receiving GPWS warning on approach.
Narrative
I was pilot flying into ZZZ when we received EGPWS alerts on the approach. ATC descended us to 3;900 near the downwind leg. I descended to 3;900 at a minimal descent rate to avoid EGPWS (Enhanced Ground proximity Warning System) alerts. We were cleared for the visual approach to runway XX. We had previously briefed the visual for runway XX backed up by the RNAV Y XX as well as the EGPWS procedures. While level at 3;900 we received a 'Terrain Terrain Pull Up' audible alert. I immediately disconnected the autopilot; started a climb; and advanced the thrust levers. We climbed approximately 1;000 feet. The Captain advised ATC that we climbed in response to a terrain warning. After assuring we were clear of terrain I began making a descent back down with a minimal descent rate to prevent another alert. We made our base turn between ZZZZZ and ZZZZZ1. While descending back down we received another 'Terrain Terrain Pull Up' alert. I responded by advancing the thrust levers again and pitching up. I was still hand flying the aircraft at this point. After assuring we were clear of terrain and turned inbound; I descended using the RNAV 24 profile / PAPIs and landed on runway XX. On short final I realized my sink rate was increasing so I added power to decrease the sink rate. The sink rate corrected itself and we landed without event. We received a sink alert a few feet from the ground but we had already corrected this and touched down immediately after the alert.Root cause narrative: Our initial descent to 3;900 by ATC was a conflict for the EGPWS system.suggestion: Ask for higher altitudes until inbound and request the RNAV XX approach.
Second reporter narrative
Crew received two EGPWS Mode 2A 'TERRAIN TERAIN PULL UP' callouts during day; VMC conditions when well clear of terrain; and one Mode 1 'SINK RATE' callout while in the landing flare during the approach and landing to RW XX at ZZZ. Crew responded appropriately to all three callouts. A safe approach and landing ensued.During introductions while waiting at the gate; we discussed the company requirements for ROA. Although I had flown into ZZZ earlier this month; and the FO indicated that he had flown into ZZZ with in the last several weeks; we nonetheless reviewed the company pages in the Jepps app; in particular those for RW XX; the anticipated runway.Prior to completing the 'Before Start' checklist; we briefed both the departure from ZZZ1; and the arrival to ZZZ. We briefed a flaps 45; visual approach backed up by the RNAV (GPS) Y RW XX; designated that I would have the Terrain display active on my side; as well as noted the recommendation on company Jepps pagesto join the approach outside of ZZZZZ.The weather was VMC; late afternoon; with the sun just above the horizon; and terrain clearly visible throughout the entire approach. Aircraft weight was ~ 43;300 lb crossing the threshold.Approach vectored us for a left-hand downwind for RW XX at an altitude of 3900 ft MSL and a heading of 060 deg. Aircraft had slowed to ~220 KIAS; with flaps at 9 deg. Approximately 7 NM due south of the airport; with the airport clearly in site; we were cleared for the visual. I advised approach of our intention proceed just past ZZZZZ prior to turning base. He advised that the terrain was higher in the vicinity of ZZZZZ; which is true; and recommended turning base earlier. I fully expected that we would be clear of any terrain by at least 900 ft during a base turn between ZZZZZ2 and ZZZZZ as the charted terrain is 3000 ft MSL in that area. Nonetheless; we briefly discussed the controller's recommendation and opted to turn earlier. I suggested to the FO to start the turn when just abeam ZZZZZ1; which would have put us between ZZZZZ and ZZZZZ1 when turning final.While still level at 3900 ft; heading 060 deg; we got a 'TERRAIN TERAIN PULL UP' callout. The FO respond promptly by disconnecting the autopilot; adding power; and establishing a climb. I commented simultaneously; 'Go; get climbing!' or words to that effect. It is very probable that we were pointed directly at the charted peak of 2610 ft; which is approximately 6 nm; bearing 110 deg from the field; so we should have been clear by some 1300 ft. Satellite imagery shows this peak; which is just south of the Reservoir; to have steep gradients on all sides; and we no doubt penetrated the Mode 2A upper boundary.I advised approach that we were responding to a GPWS callout and we leveled off at 4900 ft.We started the base turn abeam ZZZZZ1 at 4900 ft. I entered a heading of 340 deg in the command heading for the FO. He requested two more adjustments; 330 deg; and finally on 300 deg to intercept the final approach course. In order to be at an appropriate altitude to intercept the RNAV glidepath; the FO also began a shallow descent of ~500 fpm. There is a ridge line in this area (between The Overlook and Iron mine); which averages approximately 2500 ft; so again; we should have been well clear of terrain.At approximately 4200 ft; we got another TERRAIN TERAIN PULL UP" callout. The FO leveled off momentarily; as we were now clear of the ridge top with the terrain falling off beneath us.We intercepted the final approach course; both on the RNAV and visually; just outside of ZZZZZ1; at approximately 4100 ft; well above glidepath (charted height is 3700 ft at HIBAN). I told the FO we needed to slow down; and fully configure so that we could establish a controlled rate of descent and get on glidepath. He reduced power and called for the gear; which I lowered. At approximately 207 KIAS; I asked if he was ready for flaps 22; and he trapped my error; responding; 'We need to slow a bit more.' 'Yes; you are correct;' was my reply. We lowered flaps to 22 deg at 197 KIAS; to 45 deg at 144 KIAS; and had the 'Landing' checklist completed by 3200 ft. Rate of decent was approximately 1000 fpm. I commented that we had 1000 feet to get ourselves all sorted out; i.e; on glidepath and stable by 1000 ft above the field elevation. I recall making recommended power settings to the FO as he was slightly chasing the aircraft. However; we steadied out and passing thru 2200 ft; we were on centerline; on glidepath; with rate of descent ~700 fpm; and we made the 'stable' call.Thru 1700 ft (500 ft above field elevation); I made the required call 'Stable; Target; Sink X'; and my recollection is that I called 800 fpm; although I am not nearly certain on that specific point. What I am certain of was that the glidepath was centered; but a could see a high developing as the inside right PAPI light was starting to show pink vice red. I clearly remember commenting on this; the FO made a slight and appropriate power reduction. However; he held it off a bit longer than needed; in part; I suspect; due to the optics of the approach as RW 24 has an ~1% uphill gradient the first 2000 ft or so. I made two 'Power back on' calls. The FO was slow to respond to the first call; as he informed me in the debrief; he was confused by my terminology. A moment or so after my second call; he added power and began the landing flare. Just prior to touch down; we received a Mode 1 'SINKRATE' call; likely just clipping the Mode 1 envelope. Touchdown was firm; but well within normal parameters.After completing the 'Parking' checklist; we thoroughly debriefed the approach; discussing the low vectoring altitude; the Mode 2 algorithms; and the captain's confusing terminology during short final.Despite my experience; and the prep that myself and the FO did together prior to the flight; we still experienced an EGPWS/TWAS event; and honestly; I was bit surprised by the first callout. While all other aircraft I have flown; save the Caravan; are entirely able of matching the E145's speed below 10;000 ft; I have never had a GPWS/TAWS callout while straight and level and clear of terrain. At no time during this entire evolution were we in any danger of a CFIT event; even if we had totally ignored the EGPWS callouts; turned base as planned at 3900 ft; and intercepted the final approach course between ZZZZZ and ZZZZZ1."
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.