Commercial Fixed Wing
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Other / Unknown; Situational Awareness
Inflight Event / Encounter CFTT / CFIT
Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Procedure; Human Factors
Event happened while on a visual approach into OAK; for Runway 30. FMS had been set up with ILS-30 to backup the visual approach and a full briefing had been conducted prior to top of descent. The initial approach into OAK was standard; with an overfly of the straight-in approach course to Runway 30 with a right turn to join downwind. We were given our sequence and a lower altitude. While in a descent; Approach Control informed us that there was a change of plans and to maintain 4;000ft. We were currently descending through 3;800. We informed them that we were low and executed a slight climb to 4;000. From here several delay vectors were given so that space could be obtained between us and traffic to follow. The final vector was a WNW heading; pointing us towards MITOE FAF on the ILS. Approach asked if we had the field for a visual; and we did so we confirmed this. We were approximately 15nm from the field and accepted visual clearance for Runway 30. I was PF (Pilot Flying) and took a look at altitude considerations in order to manage the FCP. On the approach plate I saw the highest terrain topographic line showing terrain at 1;000ft MSL. At MITOE; glide slope intercept is charted at 2;000ft MSL. I selected 2;000ft MSL in the FCP and started a slight vertical speed descent that would have us arrive at that altitude just prior to MITOE; logic being maintaining 1;000ft vertical clearance with terrain at all times and setting up for a stabilized approach. On our heading we had a relatively sharp intercept of the LOC course and this intercept was to happen approximately half a mile prior to MITOE so I wanted to focus on proper course instead of altitude at this time and did not want to become task saturated with trying to 'dive' the airplane onto a proper glide path. The weather conditions were clear for the entire descent; approach; and landing. The terrain in which was charted and we were descending over has no light; creating a black hole effect but there are plenty of lights on the other side in which you can see if you are sinking below or rising above terrain. Visually the approach looked good. As we descended through approximately 2;500 ft; over the last part of the terrain; ATC confirmed that we had the terrain in sight and we also got the Red Warning 'L/G Not Down'. I knew of this message but couldn't remember what parameters triggered it and had a brief discussion with the Captain. He informed me it was due to terrain proximity. This was surprising because we had not received any Radio Altimeter audio callouts; such as 2500 and 1000. Using the vertical speed function of the FCP; I put the plane into a slight climb while we took a look to confirm that our approach was safe and we were not missing anything. A second message went off just as the first had; both were intermittent. By the time the second one had finished we were fully clear of terrain; and continued the approach to a normal landing. For the entire approach I also used the terrain on the Captain's ND (NAV Display) to enhance situational awareness and never saw anything more severe than solid green with a small section of partially shaded yellow.The detection was very simple. The first cue was a call from ATC. They never alerted us to the being below a minimum safe altitude or gave us an altitude alert; but rather it felt like just a check-in. The second more serious cue was the Master Warning message. Being unfamiliar with the specific triggers for this message I thought it came on at 1;000ft RA (Radio Altimeter); which was lower than I intended to be and was cause for a level off. After landing I looked it up and saw that the message triggers at 750ft and this was about 700-800ft less of terrain separation I thought we had; based on the approach plate and subsequent lack of RA audio callouts. There are two primary causal items that I see in this situation. The first is ATC. They did a poor job managing us and the other traffic in the area; and then theysimply 'cut us loose' in an odd position. It felt as if they were tired of providing vectors and separation so they wanted to wash their hands of it. The second causal factor was myself. I felt comfortable on the visual approach; although I realized it was nonstandard in how far we were out and our altitude. Usually more guidance is given and I probably should have insisted on further vectors and altitudes from ATC. Another personal factor is my experience level in the plane. I am new to my position and still gaining familiarity with how to most effectively configure the plane on approach in order to ensure a stable profile and prioritized altitude on the final straight in over altitude on the approach leading up to that. I didn't list this event as GPWS because we never received any EGPWS warnings or cautions. None of the modes activated. I knew when the L/G (Landing Gear) message displayed that our RA was indicating we were lower than I initially thought; and realizing my situational awareness was incorrect we halted the descent. Terrain clearance had been satisfied in my mind using the approach chart; the terrain on the ND; and visually. This has been a learning experience for me and I will be less open to the idea of accepting a visual approach at night over completely dark terrain; especially from a nonstandard set up.
Air carrier First Officer reported a CFIT event during a night visual approach.